Washington State University Extension

Garden Tips

Archive for December 2008


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

What is topsoil? Technically, it’s the natural top layer of soil on the ground. It has been created over thousands of years by a combination of factors…weather, climate, and decaying organic matter from the native plant vegetation. Topsoil is usually only about six to eight inches deep and contains more organic matter and microorganisms than the soil beneath it. It’s not a surprise to area gardeners that our native topsoil isn’t the “dark, crumbly, rich soil” found on forest floors. We have a very different climate and as a result, very different soil.

It’s a recommended practice to scrape topsoil off of a building site and stockpile it at the side of the site before construction begins with the intention of returning that same topsoil after construction is complete. While this procedure preserves topsoil, a precious natural resource, it’s often not followed exactly as prescribed.

Too often the topsoil is not removed at a building site, leaving it vulnerable to severe compaction. Once a structure is complete, they may bring in something that’s called topsoil, but it’s usually not native area topsoil. Instead, it’s often a designed topsoil or a topsoil mix that has been purchased as topsoil. This mix may contain a variety of three or more different materials such as sawdust, compost, manure, biosolids, sand, and soil. There are no legal standards regarding what can be sold as “topsoil.”

According to WSU Extension Specialist, Dr. Linda Chalker-Scott, these topsoil mixes are often composed of 15 per cent OM (organic matter) by weight. An “ideal” soil contains about 5 per cent OM by weight. Soil tests performed on local home garden soils have typically indicated OM content of less than one per cent.

Chalker-Scott points out that in a permanent landscape situation, such as a lawn or landscape, the OM eventually (within ten years or probably in much less time here) breaks down and disappears, causing the soil to settle and compact. This leads to the trees, shrubs, and grass sinking to well below grade. Instead of using a topsoil mix with excessive amounts of OM or adding volumes of OM to the existing soil, she says it’s better to use the soil that is in place and mulch trees and shrubs with wood chips.

The other problem with the use of these topsoil mixes is water penetration. When the topsoil mix is simply laid over the top of the ground, the soil beneath is usually not broken up or loosened in any way. It’s hard for water or roots to penetrate highly compacted soil. The soil at the site should first be loosened by tilling or ripping to help improve water movement into the soil beneath the applied “topsoil”.

Mixes can also present water movement and drainage problems… even when the lower soil is disturbed and loosened. This is because water easily moves through the typically coarser texture of the mix, but it doesn’t enter the finer soil beneath it as quickly. This leads to what is called a “perched” water table. Water sits on top of the lower layer of soil for a long time before it enters. This creates wet and soggy conditions and can lead to root rot.

There are no easy solutions to this problem. If you must bring in new topsoil, the compacted soil on the site should first be loosened by tilling or ripping. The topsoil should then be tilled into the top layer of the existing soil to avoid the interface problem of two different textures. Better yet, the compacted soil should be loosened and native top soil returned to the site if it was removed. No significant amounts of OM should be added. Trees and shrubs should be mulched with compost and wood chips.

If you’re purchasing topsoil, check out what you will be getting before its delivered. Ask the seller what the topsoil contains and also ask for the producer’s test data regarding pH, salt level, nutrient levels, OM content, and texture. If they don’t have that data available, you may want to consider taking a sample and have it tested yourself. Also, find out if the soil has been screened to remove rocks. Before you’re stuck with unsuitable topsoil, know exactly what you’re getting.

Garden Hint: Topsoil is usually sold by the cubic yard. One cubic yard of soil will cover about 50 square feet to a depth of four to six inches.

Published: 4/28/2007 2:25 PM


Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA Invariably I get asked to talk about how to ‘put the garden to bed’ in the fall, but no one asks me to address how to ‘wake up the garden’ in spring. Apparently, there’s no need for that. Warm temperatures and longer days do a pretty good job of that without my help. Gardeners are just itching to get out and get the gardening season started. The timing is perfect, there are a number of garden tasks that require our immediate attention… PRUNING: Flowers and leaves will be popping out any day on many of our fruit trees, shade trees, roses and shrubs. If you haven’t done your winter pruning already, now is a great time before new growth makes it difficult to see the plant’s framework. Keep in mind woody plants don’t ‘need’ to be pruned. Always prune with a legitimate purpose in mind. Good reasons to prune are to remove dead or diseased wood; to correct ill-placed growth where limbs are crowded or rubbing each other; to get rid of growth that’s posing a hazard; to correct growth defects caused by narrow branch angles or past improper pruning, or to encourage better flowering and fruiting. You should have used the winter respite to clean, oil, and sharpen your pruning tools. Do it now, if you didn’t earlier. Now is a good time to consider investing in a quality pair of bypass hand pruners and bypass loppers, and possibly a small pruning saw too. Pruners with a bypass (hook and blade) mechanism make a cleaner cut than anvil types that crush the stem, leaving damaged tissue behind On multi-stemmed flowering shrubs such as forsythia or lilac, you may find you also need a small pruning saw. On these shrubs it’s recommended that you take out 1/3 to 1/5 of the oldest wood, cutting it back to just a few inches above the soil. You should also remove any crowded spindly growth. I do this every spring on my wild and gangly forsythia. It amazes me how much wood I can take out and it still grows and grows. And yes, now is the time to prune your floribunda and tea garden roses, as well as most other types of roses. The proper way to prune varies from type to type. Before you cut, find out the proper way to prune each type. Now is also the time to ‘prune’ or trim ornamental grasses and perennials. You can use hand pruners or scissors to cut back smaller clumps of grasses, but light-duty hedge trimmers will work best for larger clumps. To make cleanup easier, use twine to tie the top growth together and then cut the grass back four to six inches above the soil. New green shoots will soon appear. Trim back dead perennial stems and flowers, if you didn’t get it done late last fall. I also cut back my perennial herbs, like sage, to keep them a bit more tidy and within the bounds of their allotted garden space. The hedge trimmers come in handy for both these jobs too. IRRIGATION: Check out your irrigation system and make sure it works as soon as you have water available. While it wasn’t a harsh winter, damage may still have occurred to sprinklers and drip lines. Before hot weather arrives, check the coverage your sprinklers are providing. You can do this by placing empty straight-sided tin cans in different areas of each zone, radiating out from the sprinkler heads. Run the system for a set amount of time. Measure and compare the amounts of water (by depth) in the cans. If there is a wide disparity, you may need to adjust your heads or get new ones that can provide a more even pattern. The folks at the irrigation supply store should be able to help you with this. Despite our winter precipitation, yard and garden soils are fairly dry right now. As soon as you have irrigation water available give trees, shrubs, gardens, and lawns a thorough watering that moistens the soil to a depth of at least a foot. LAWNS: I know you’re tempted but it’s not time to fertilize the lawn yet. Wait until the first of May for that. It is definitely time to apply crabgrass and weed ‘preventer’ chemicals to your lawn. However, this may lead to a dilemma for you because many of the ‘preventer’ products only come in combination with fertilizer. Stand-a-lone preventers are available, but you’ll have to look a little harder for them. Timing is not as crucial with products containing the chemical dithiopyr because it will provide both preemergence control, as well as some postemergence control of young crabgrass plants. However, before you buy any product, make sure that the weeds you think are crabgrass really are crabgrass. Lots of people are battling Bermuda grass and bentgrass, thinking their problem is crabgrass. If the thatch in your lawn is greater than one-half inch thick, you should consider ‘dethatching’ with thatch removal equipment. This should be done before the middle of April. It also should be done before the application of any weed ‘preventers.’ GARDEN STRUCTURES: As you go about the yard and garden, check out your garden structures for any needed repairs. Now is when it’s easiest to fix arbors and trellises… without the green growth of vines and climbing roses to obscure what might need nailing or wiring. See if any furniture or garden benches needs a new coat of paint or stain. Clean bird baths out thoroughly. Check for loose stepping stones and patio pavers and secure them.

Published: 3/25/2006 11:24 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

When the Pilgrims arrived in Massachusetts the week before Christmas in1620 they found a plant that reminded them of the holiday season they were missing back home (according to the U. S. Forest Service in their “Silvics of North America”). The plant they discovered was American holly (Illex opaca) which strongly resembled the English or European holly (Ilex aquifolium). English holly has been associated with Christmas and used for holiday decorating for many centuries. The American holly looked very similar to the English holly with its prickly leaves and red berries.

The use of English holly in connection with a winter holiday even predates Christian tradition, going all the way back to the times of the druids and pagan Romans who associated holly with the God of Saturn. Holly was used to celebrate the Feast of Sol Invictus on December 25th. This special day was to honor the return of the sun and increasing day length. Holly later became part of Christmas holiday legends and decorating traditions.

American holly is native to the eastern part of the U.S. from Massachusetts to Florida, thriving in the mild and humid regions of the southeast. It grows best in slightly acid, rich, moist soils that are well drained. In its native range, the American holly tends to grow best as an understory tree in deciduous forests. In the home landscape it can be placed in partial shade and full sun, except for areas like ours that have extremely low humidity, intense summer sun, and very high summer temperatures. In this part of Washington it’s best to locate the plants where they’ll be protected from heat and afternoon sunlight.

Both the American and English hollies are dioecious. This means that some plants are male and only produce male flower and some plants are female and only produce female flowers. For fruit to develop, female flowers must be pollinated by pollen from male flowers. This means that if you plant a female holly you also need to plant a male holly nearby to get decorative red berries on the female. The male must be within 200 feet from the female for the bees to provide adequate pollination. If that isn’t practical in your landscape situation, you may want to consider one of the grafted plants that can be found at some nurseries. Male wood is grafted onto the female plant so one plant can produce both female and male flowers on different branches.

English and American hollies are members of the holly family (Aquifoliaceae) and belong in the same genus (Ilex) along with 400 other species. The native form of the American holly grows into a 30 to 50 foot pyramidal tree. That’s too big for most home landscapes, so plant breeders have developed a number of different cultivars (cultivated varieties) that vary in plant size and shape, in berry color, and in foliage form and color.

‘Clarendon’ is a shrub dwarf form growing to only eight feet tall with a wider spread.

‘Maryland Dwarf’ is even smaller with a height of three feet and a spread of ten feet, but it produces few berries.

‘Howard’ – is a cultivar for gardeners who don’t like messing with the spiny leaves of holly. It has leaves that are practically spineless.


s Silver Crown

– produces leaves edged with creamy white.

Ilex opaca f. xanthocarpa is a naturally occurring form of American holly that has yellow berries. ‘Canary’ is a cultivar selection of this that produces lots of yellow fruit instead of the expected red.

is a naturally occurring form of American holly that has yellow berries. ‘Canary’ is a cultivar selection of this that produces lots of yellow fruit instead of the expected red.

If you want to grow your own Christmas tradition, consider America holly. Check with your local nursery to see which cultivars they carry.

Are holly berries are poisonous? Yes the berries are poisonous, but are not considered extremely toxic unless eaten in quantity. However, because they are poisonous they should be considered dangerous to small children.

Are English hollies a noxious weed? English holly has been planted commercially in the Pacific Northwest for decorative floral uses. While it’s not yet classified as a noxious weed on the Washington State Noxious Weed List, it has become a serous concern in natural areas, mostly in western Washington counties. The English holly, spread by birds feeding on the berries, has become naturalized and forms dense thickets, suppressing the growth and germination of native tree and shrub species. Restoration of native areas includes removal of English holly that has become established. Instead of planting English holly, consider planting Merserve hybrid hollies, such as ‘Berry Magic.’ ‘China Boy’, ‘China Girl,’ ‘Blue Boy’, ‘Blue Girl,’ ‘Blue Prince’, ‘Blue Princess,’ and Ebony Magic‘. These all are more dense than English holly and only 15 to 18 feet in height. Do not plant them in full sun.

Published: 12/17/2008 1:24 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Nobody told me. Did they tell you? This year, 2008, is the International Year of the Potato! Here in the Columbia Basin the potato certainly isn’t a second class vegetable. It’s importance to our regional agriculture is recognized by many. However, for those of you that aren’t impressed with the history and importance of these soil grown nuggets, let me enlighten you.

The potato (Solanum tuberosum) is an herbaceous annual in the Nightshade family and is related to tomatoes, peppers, eggplants, and the deadly nightshade vine. What’s unique about the potato is its tubers that develop underground. Tubers are modified stem tissues that the plant uses to store starch.

Potatoes are truly an American crop. About 8,000 years ago farmers in the Andes mountains of South America first began growing the potato. Through selection they were able to improve this humble wild tuber into a crop that provided food security for their burgeoning population. The potato helped give rise to the South American Huari and Tiahuanacu civilizations. While these civilizations collapsed with the rise of the Incas, the potato persisted and was a staple of the Incan diet. The Incans even developed a freeze-dried potato product and had numerous storages for harvested potatoes.

The invasion of the Spanish in the 1500

s brought about the demise of the Incas, but again the potato survived. The conquistadors took the potato back to Spain and the Spanish introduced it to the rest of Europe. However, the potato wasn’t quickly embraced as a nutritious food crop and was first viewed as more of plant oddity and a food source for animals.

Suspicions about the edibility of potatoes slowed the Europeans embracing the potato as a food crop. The potato’s slow acceptance was also due to its poor performance as a crop under European growing conditions. The potatoes that were first planted in Europe were better adapted to the cool short day conditions found in the Andes mountains. Over time, the Europeans were able to make selections and developed potato varieties that produced better under longer day length conditions. Due to famine, the potato became an important food security crop throughout Europe in the1700


Through European exploration, colonization, and emigration, the potato became cultivated throughout the world. It’s now part of the global food system. It’s ranked fourth as one of the world’s most important food crops, with only corn, wheat, and rice ranking higher. The world’s biggest potato producer? It’s China. Behind China are Russia, India, Ukraine, and the U.S. Top consumers per capita of potatoes are Europeans, with almost double the per capita consumption of North Americans!

Potatoes are a fairly easy crop to grow and gardeners might want to consider adding them to their gardens if they don’t grow them already. When my youngest son had a 4-H garden project, his best crop was always potatoes. While not in touch with his “inner green thumb,” he was still able to grow blue ribbon potatoes.

Of course, many gardeners don’t want to bother growing a crop they can easily buy relatively inexpensively at the grocery store. However, you’re missing out on a number of heirloom varieties of potatoes that offer a greater diversity for tasty consumption. My favorites are red-skinned varieties, such as Sangre, Cherry Red, and Viking Red. Seed potatoes of these and other types can be ordered from two Northwest producers, Ronniger Potato Farm LLC ( and Irish Eyes Garden Seeds (

To plant potatoes, till your garden to loosen the soil and then plant mini-tubers or seed potatoes (cut pieces of potato with one or more eyes) in rows. Make a trench and place the seed pieces about a foot apart and then cover them with about three inches of soil. If you have more than one row, space the rows about three feet or more apart.

Plant early in the season when the soil has warmed a bit to above 50 degrees Fahrenheit. Potatoes are a cool season crop, and grow best during the moderate weather of spring and early summer. However, when planted too early they will just sit in the ground and rot before sprouting and growing. A good date for planting is about six to eight weeks before the last average frost date for your area. (May 1 to May 15 is the average date for the last frost in our area.)

Obviously, potatoes do well in most well-drained Columbia Basin soils. The special trick for success with potatoes in our gardens is providing even moisture through the season and fertilizing with nitrogen. Irish Eyes Garden Seeds recommends fertilizing the vines early in the season with an organic foliar fertilizer, such as a fish emulsion or seaweed product. You may also add a nitrogen fertilizer to the soil at planting time. My son worked rabbit manure into the soil before planting tubers.

Since this is the International Year of the Potato let’s celebrate it at Thanksgiving by eating some of these nutritious American tubers that have become a staple food around the world.

Published: 11/22/2008 1:33 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

We can blame ourselves as gardeners for some of the troublesome weeds in our yards, gardens, roadsides and natural areas. Many noxious weeds are non-natives that were brought into this country as ornamental garden plants that later escaped. They now threaten native wild plant and animal life or cause us trouble in our gardens and landscapes.

Pampas grass is one of those non-natives ornamentals that has escaped. While some will adamantly avow that pampas grass isn’t invasive, others will swear that it’s already a serious invasive weed in parts of the US. Part of this disagreement is the result of the confusion resulting from the two related types of grass commonly called pampas grass. One is the common garden pampas grass (Cortaderia selloana) that has been considered non-invasive and its close relative is Jubata grass or Andean pampas grass (Cortaderia jubata) that’s known to be highly invasive. Both are native to South America.

The Andean pampas grass is the “bad” cousin of the two. It’s very aggressive in open ground that’s bare or has been disturbed. In California, Andean pampas grass is a serious concern in coastal areas. The seeds of this grass develop without pollination and the plant readily seeds itself. The “good” cousin, the garden pampas grass, has been considered non-invasive in the past. That’s because it’s dioecious with separate male and female plants. For viable seed to occur, the female flowers need to be pollinated with pollen from male flowers. Because the female flowers or plumes are whiter and showier, nurserymen and gardeners have traditionally only grown female plants. These are easily propagated by vegetative divisions of other female plants.

As long as male plants aren’t grown in the same area, few viable seeds are produced and the garden pampas grass is not invasive. However, in recent years some unwitting or unscrupulous nurseries have propagated garden pampas grass from seed and sold the resulting plants not knowing if they’re male or female. This has resulted in more of the male plants being planted and has resulted in this “good” cousin becoming very invasive in areas of California, Hawaii, as well as other areas.

In warmer regions it’s understandable that garden pampas grass can thrive. However, as a warm-season grass rated as hardy to USDA Zone 8, it shouldn’t survive and grow well in colder regions, but it does. In warmer climates it’s leaves stay green during the winter, but in colder climates they turn brown in winter like many other ornamental grasses. The plants will survive down to 10 degrees Fahrenheit and the crown will only be killed if the soil freezes deeply during the winter.

Personally, I think the term “garden” pampas grass is a misnomer. This ornamental grass is not for the ordinary garden. The clumps can grow up to five feet wide. The plants may grow to ten feet tall with flower stalks with plumes reaching to 12 feet tall. It takes about three years before it produces flowers. In late winter, the plants are cut back to about 18inches from the ground. This is no easy task! The edges of the leaves are extremely sharp and the plant is very dense. The best tool for cutting it back is a small chainsaw. That’s what I call extreme gardening!

Of course, like with so many garden plants, there is a dwarf form of this gargantuan grass. It’s dwarf pampas grass, Cortaderia selloana


. Keep in mind though that “dwarf” is a relative term. Dwarf pampas grass plants reach a size of 4 to 6 feet wide and 5 feet tall. It produces 10 foot long flower stalks with silvery white plumes. Once established, it does well in scorching sun and tolerates drought and wind. It’s also hardy down to USDA Zone 6. This one is also cut back to 18 inches from the ground in late winter with a chainsaw!

There’s also another grass that’s commonly referred to as pampas grass. The hardy pampas grass (Saccharum ravennae, previously known as Erianthus ravennae) is not related to the bad and good “cousins”. The hardy pampas grass is native to north Africa and the Mediterranean. It resembles true pampas grass with plants that grow 6 feet wide and 10 to 15 feet tall with silvery white flower plumes that look somewhat like the fluffier pampas grass plumes. There are also concerns about growing this grass because it’s already shown itself to be invasive in parts of the West.

Environmentally conscientious gardeners should avoid planting any of the pampas grasses. They pose potential threats to our native wildlife, plus they’re pretty big for the average gardener to manage. I know I won’t be planting one anytime soon. If it becomes a noxious weed here, I don’t want to have that on my gardening conscience.

Published: 11/15/2008 1:34 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Gardeners who know me will tell you that I’m fussy about the potting soil I use. No matter how green your thumb is you can’t grow first-rate plants in containers without a first-rate potting mix. Before the soilless potting mixes were developed at Cornell University and other institutions in the 1970

s, greenhouse growers and gardeners had a tough time growing plants in pots. Plants were often lost due to poor nutrition, disease and insect pests. The formula for the “Cornell Peat-Lite Mix” was developed by Dr. Raymond Sheldrake, Cornell University professor of crop science (who died last month at the age of 85) along with Dr. James Boodley, Cornell University professor of horticulture. They came up with one of the first soilless mixes that could be used to successfully grow healthy plants in containers indoors and greenhouses.

The recipe for the Cornell Peat-Lite Mix was published in the 1970s, but growers were at first doubtful about its benefits. However, it didn’t take them long to discover the use of the soilless mix meant an 80 per cent reduction in plant loss. This first mix was a combination of peat moss, vermiculite, limestone and fertilizer nutrients and was later changed to allow for the substitution of perlite for vermiculite. Since that time, others have come up with their own blend of ingredients, some quite different from the original university researched “recipe”. As with other types of recipes, changes and substitutions can make a recipe better… or not so good.

A quality potting mix is porous having both good aeration and drainage while having good water holding properties. For many years the basic ingredient of most quality potting mixes, like the Cornell Peat Lite Mix, has been premium sphagnum peat moss because it provides these needed characteristics. Most peat moss used in the US is harvested from peat bogs in Canada. Because of the concern over the sustainability of the practice of harvesting peat moss from bogs and the increasing costs of transporting the peat moss, substitutes have been tried.

Poorer quality mixes typically use bark or wood product-based compost as their basic organic component. When bark is used, it should be fairly fine in texture and fully composted. If not fully composted, it will continue to decompose and break down. As bark decomposes, the plants growing in it will need more nitrogen than in more stable peat-based mixes.

Potting mix producers continue to look for environmentally sensible organic materials that would have the same or close to the desirable properties of peat moss. Coconut coir is one of these materials. It’s a by-product of the coconut fiber industry. Because it’s manufactured in India, Sri Lanka, the Philipines, Indonesia, and Central America, it tends to be even more costly than peat moss due to shipping costs. While coir-based mixes might cost more, the coir tends to last two to four times longer than peat, it doesn’t resist wetting like peat, and it holds more water than peat. It’s also a way of utilizing a waste byproduct of the coconut fiber industry.

Yet another is fiber being introduced into the potting soil market. It’s a byproduct of anaerobic digestion of dairy manure. At two Washington dairies, manure is being anaerobically digested to produce methane which is then used to generate electricity. The byproducts of this methane production via anaerobic digestion of manure are a liquid portion that’s used as a fertilizer for nearby crop land and a fiber portion. This digested fiber looks a lot like peat moss in color and feel. It also has similar density, water retention, and porosity, but it’s pH is higher. To successfully grow plants, the fiber must be treated to acidify it. WSU research indicates that when treated, plants will grow as well in digested fiber mixes as they do in peat mixes. What makes it even more suitable is that it’s produced in this region from a sustainable source, this environmentally friendly manure waste management system.

As concern over the harvesting and use of peat moss in the horticulture industry continues to increase, I’m sure researchers will be looking for other plant fiber byproducts that can be used to replace peat moss and protect the Canadian bogs. Even though I’m partial to the “tried and true” peat-lite type mixes, I’m willing to try some of the new mixes as soon as they become available. While they’ve been slow to turn up on Tri-City area garden store shelves, I know they’re coming!

Published: 11/8/2008 1:35 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

During the last few months, a number of local gardeners, including myself, noticed that many of our garden plants were infested with zillions of tiny white flying insects. The culprit was the greenhouse whitefly (Trialeurodes vaporariorum). It attacks a number of garden veggies and annual ornamentals. The greenhouse whitefly doesn’t overwinter outdoors in the garden in this region. This means that the source of infestation was most likely some of the transplants that we purchased at the beginning of the season.

There are over 200 known species of whiteflies, but only a few of these cause real problems on plants. The adult greenhouse whitefly is about 1/10 to 1/16 of an inch in length and looks like a tiny moth. As the name implies, their bodies are white and covered with a white powdery wax. Most gardeners notice them only when they’re present in large numbers… when they envelop plants in a cloud-like swarm. If you can find one at rest you’ll see that they hold their wings in a tent over their body.

With favorable conditions, the adult whitefly has the potential to lay up to 400 eggs, depositing approximately 25 a day on the undersides of plant leaves. In about a week, these eggs hatch into nymphs. After transitioning between three distinctly different immature stages the nymphs turn into adults in a month. The adults can live as long as 45 days. Both the adults and nymphs have sucking mouth parts and feed by sucking sap from the plant.

Heavy infestations of whiteflies can stunt plants and cause their leaves to turn from yellow to brown and dry, but light whitefly infestations usually don’t cause serious problems in the garden. However, as they feed the whiteflies excrete sugary “honeydew.” This doesn’t harm the plant, but it can make plant parts very sticky.

That’s what happened to my tomatoes this year. Infested with whitefly, I had to wash the sticky fruit before eating. I didn’t worry about the whiteflies on my tomatoes because it was a light infestation that wasn’t causing significant damage. I also knew that all the flies would die with frost in the fall. Next year I plan to inspect my transplants before buying them to make sure they don’t have whitefly. It also pays to check them several weeks after planting in the garden to make sure an infestation hasn’t gotten started. If an infestation is noted, there are some easy non-chemical approaches that you can take, such as removing infested leaves and using water to wash the flies and dust off the plant.

Insecticides are not routinely recommended for whitefly control for several reasons. One reason is that non-selective insecticides kill the many beneficial insects, such as lacewings, minute pirate bugs, and lady beetles, that help keep whitefly populations under control,. Because of this, it’s best to avoid using carbaryl, pyrethroids, or foliar sprays of imidacloprid. Dust protects the whiteflies from some of it’s enemies. Keeping the dust washed off leaves will encourage the work of beneficial insects.

Another reason not to use most insecticides is that whiteflies also have a tendency to build up resistance quickly to different chemicals. Insecticidal soaps can be used to keep populations down. Spray in the early mornings when the temperatures are cool to avoid damaging plants and to have the soap come in contact with the adult whiteflies while they’re sluggish and not as likely to be flying about. Be sure to spray the lower surface of the leaves, especially the lower leaves of the plant. Soap will only kill the nymphs to which it’s directly applied. It does not kill the eggs, so repeat applications are usually needed.

A unique approach to control is using a small handheld cordless vacuum to suck up the adults from the leaves. This is also done in the early morning when the adults are slow and sluggish. When the vacuuming task is completed, be sure to freeze the flies by placing the vacuum bag in the freezer for a day. (You may want to put it in a plastic bag before putting it in your freezer.)

With heavy frost, the whiteflies plaguing local gardens are gone now. Next year avoid reintroducing them into your garden by making sure your transplants are “whitefly-free” when you bring them home.

Published: 10/25/2008 1:36 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

No place for a compost pile in your yard? Gardeners don’t have to build a classic ” pile” to recycle yard and kitchen waste via the natural process of decay. There are other ways to compost that don’t involve constructing a pile and building or buying something to contain it. Alternatives include sheet or layered composting, trench, and pit composting.

Sheet composting is an easy method that works well if you have a veggie garden that’s not permanently mulched. All you need to do is chop up your plant waste and spread it out in your garden as a layer of mulch. If you collect your grass clippings, it’s a great way to get rid of them and use them to help build your soil. One word of caution, a heavy layer of fresh grass clippings tends to form a mat and impede water and air movement into the soil. Try to vary the texture of your layers or allow the grass clippings to dry out before placing them in the garden.

You can also use this method with other types of yard and garden waste, but it’s important to chop it up before applying it to the garden. If you don’t have a chipper, you can chop up non-woody plant waste using your mower. This works best if you place the plant waste on your lawn and run the mower over it a couple of times. Then rake up the chopped waste and spread it out in the garden.

Our fall and winter weather tends to be quite breezy, so sheet composting in the fall is not practical in wind exposed situations. However, you might find that trench composting would work for you. This is pretty simple. Just dig a trench in your garden and fill it up with your garden waste. More waste will fit into the trench and it will all rot more quickly if you chop it up first. Cover the trench with soil and water it all in. Over the late fall and winter months these materials will decay and then can be tilled into the soil next spring. If we have dry and mild late fall and winter weather, consider watering the trench area of the garden several times to help aid with decay. The microbes and little critters that are the “workhorses” of the decomposition process require moisture to live and do their job.

Yet another way to compost is in a pit. Pit composting isn’t a practical way to get rid of volumes of yard waste, but you can use it for plant-based kitchen waste. Just dig a little pit in your garden and fashion a board to cover the hole so no person or creature accidentally falls into it.

As you accumulate fruit and vegetable waste in the kitchen, take it out and put it in the pit. Some gardeners have a covered container that they keep near the sink to collect the waste to minimize the number of trips. Definitely do not put meat, dairy, or foods containing fats or oils in your pit compost. These are very smelly as they rot and can attract both flies and animals. However, it’s okay to put coffee filters, tea bags, and egg shells in a pit compost.

You can add new waste to the pit compost at any time. The waste will decrease in volume as it decays from the bottom up. Once the hole is completely filled up and doesn’t significantly decrease in volume with time, cover the pit with soil and dig a new pit nearby. It’s a simple way of composting and enriching the soil at the same time.

If you have lots of yard, garden, and kitchen waste, you can always build a compost pile and contain it in some way, such as a bin. However, now you know some other ways to get rid of your yard waste. If you have humongous volumes of waste, you may want to try all of these methods. Whatever way you chose, you’ll be recycling your waste into the soil and helping build up the organic content of your soil. This will mean a healthier garden and less solid waste going into the landfill.

Caution! There are some wastes that shouldn’t be put in compost piles, trenches, or pits:

Onion and Garlic Peelings: Uncooked garlic and onion waste can spread disease to the garden.

Potato Peelings: Uncooked potatoes and their skins can introduce harmful nematodes to your soil.

Pet Manure: Dog, cat, and pig manures may contain diseases and parasites that can potentially infect humans. Rabbit manure is considered safe.

Perennial Weeds or Weeds with Seeds: Perennial weeds, such as Bermuda grass and bind weed, should not be composted in anyway. Even the “hot” composting process of a pile may not kill perennial weeds or weed seeds. Annual weeds without seeds may be composted. Also avoid composting diseased plants, such as flowers with mildew.

Published: 10/18/2008 1:37 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Are organic fertilizers better for my lawn?

It would depend on your definition of “better.” Organic lawn fertilizers are made from a variety of plant and animal by-products. Manufactured fertilizers are made from petroleum or natural gas. Each type can provide the needed nutrients for a healthy, attractive lawn if used correctly.

Most organic fertilizers depend on soil microorganisms to break down the organic components before nitrogen will be available to the grass. Because the microorganisms do their best work when the soil is warm and moist, the release of nitrogen from organic fertilizers is very, very slow when the soil is cold or dry. Because of their nature, a much larger volume of material is needed with organic fertilizers in order to apply the recommended amount of nitrogen. Organic fertilizers help build soil health by adding organic matter and enhancing the microorganism activity in the soil. Manufactured fertilizers do not contribute to soil health.

Most manufactured fertilizers are not dependent on microorganisms for the release of nitrogen. Nitrogen is typically almost immediately available, although those containing slow-release forms of nitrogen may depend on soil microorganisms for the release of that nitrogen. Smaller volumes of the manufactured fertilizer are needed to provide for the lawn’s needs and they tend to be less expensive.

Can you recommend a good organic lawn fertilizer?

It’s difficult to recommend a particular brand because there are so many products and there is no readily available research comparing their qualities. Most of the commercially available products are dry plant and animal by-product based fertilizers. Protein from these plant or animal sources, such as meal from alfalfa, corn, feather, meat, or blood, are the source of nitrogen in many of these organic fertilizers. As a “green” consumer, I would check the percentage of nitrogen an organic fertilizer contains, the cost per pound of nitrogen, the ease of application and the type of packaging.

Is fall a good time to aerate the lawn?

Yes, fall is a great time to aerate your lawn, although you can aerate almost anytime except during the hottest part of summer. Be sure to use a hollow-tined aerator that removes plugs of soil, grass, and roots and places them on the surface of the lawn.

Pay special attention to where heavy foot traffic or use has compacted the soil. To be effective tines should be two to three inches deep and two to four inches apart. If they’re further apart, you can do several passes over the lawn so the holes end up with that spacing.

Be sure to water your lawn thoroughly the day before you aerate to make it easier for the tines to penetrate the soil. It’s advisable to mark the location of your sprinkler heads and any shallow underground lines or cables before you aerate.

Does aeration control thatch?

Aeration is not an effective way to control excessive thatch in a lawn, although it can help with water penetration if the thatch is preventing water movement into the soil. However, this is only a temporary fix. Dethatching with a power rake is the only effective way to reduce a thick thatch layer in turf. Power raking should be done in the spring before the middle of April.

When can I quit mowing my lawn?

Quit mowing when your grass stops growing. Don’t mow it extra short and stop mowing and don’t stop mowing and let it go into winter extra long.

I have a problem with crabgrass in my lawn. Is there anything that I should be doing now so it won’t be a problem next year?

Other than pulling up individual crabgrass plants before they drop their seed there’s not much that can be done right now, except you should fertilize your lawn at the recommended times. Proper fertilization, mowing, and irrigation encourages a dense turf that’s less vulnerable to infestations of crabgrass and other annual weeds. Next spring, you should also consider applying a crabgrass pre-emergent herbicide or “crabgrass preventer” at the correct timing..

Published: 10/11/2008 1:37 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

It’s seems to be that time of year when there are lots of questions asked about lawns and fall lawn care. I thought this list of Frequently Asked Questions and their answers might address the lawn questions that have been no doubt plaguing you as you drift off to sleep at night. Hope it helps.

When should I fertilize my lawn this fall?

WSU Extension recommends that you fertilize your lawn four times a year. Two of those times are in the fall, once in early September and again in early November.

If I didn’t fertilize in September, should I put on a double dose in early November?

No, just put on the recommended amount for your lawn in November. Each application should only contain one pound of nitrogen per 1000 square feet. The only exception to this is the application rate of natural organic lawn fertilizers. These fertilizers are very low in nitrogen and that nitrogen becomes available to the grass plants very slowly. You should usually double the rate of the natural organic fertilizers, since only half of the nitrogen it contains will be available to the grass the first year.

Do you recommend a special “winterizing” fertilizer formula?

No, but we do recommend a fertilizer with a high percentage of nitrogen in a slow-release form. When in the slow-release form it gradually provides the nitrogen to the grass, rather than all at once. Quick-release or water soluble nitrogen is easily leached out of the root zone by irrigation and precipitation.

Special winterizing fertilizers are often more expensive and contain higher levels of potassium. Potassium does enhance cold hardiness in turfgrass and may be beneficial if a soil test indicates that the soil is low in potassium. However, if the lawn fertilizers you regularly apply contain some potassium, the levels of potassium in the soil are probably adequate. Extra potassium will not provide any additional benefit and excessive levels can harm the grass. Also, the winters in our region are usually not severely cold enough to warrant worrying about applying potassium for improving grass hardiness.

Should the lawn be wet or dry when I apply fertilizer? If applying a granular manufactured fertilizer, do it when the grass is dry. Right after fertilizing, water the grass just enough to wash the fertilizer off the leaf blades into the root zone. If the soil is dry, irrigate right after fertilizing as you normally would for a dry lawn. If you use irrigation water and it’s not available for your November fertilization, try to apply the fertilizer just before rain is anticipated. If you use city water for lawn irrigation, apply the fertilizer, water, and then have your system blown out.

If applying a granular manufactured fertilizer, do it when the grass is dry. Right after fertilizing, water the grass just enough to wash the fertilizer off the leaf blades into the root zone. If the soil is dry, irrigate right after fertilizing as you normally would for a dry lawn. If you use irrigation water and it’s not available for your November fertilization, try to apply the fertilizer just before rain is anticipated. If you use city water for lawn irrigation, apply the fertilizer, water, and then have your system blown out.

How do I figure out how much fertilizer to apply?

It’s easy. First determine the area of your lawn. You will need 1 pound of nitrogen per 1000 square feet. Once you know how many pounds of nitrogen is required for your lawn, multiply that number by 100. Divide this by the percentage of nitrogen in the fertilizer that intend to purchase. For example a 4000 square foot area lawn will need 4 pounds of nitrogen. Multiplied by 100 you end up with 400. If your fertilizer is 21 per cent nitrogen, you divide 400 by 21. With these simple calculations, you find out that 19 pounds of fertilizer are needed for fertilizing your entire lawn.

Can I apply seed to the bare spots in my lawn now?

If you’re going to seed bare spots, spring is the best time. With the chance of hard frost during October, now is not a good time to sow grass seed. Early September is about the latest you can safely seed and be sure that the grass will sprout and survive cold weather.

Can I sod a lawn now?

Yes, you can sod a lawn almost anytime of spring, summer, and fall. However, it should be done early enough in the fall (and late enough in the spring) so that irrigation water is available to keep it from drying out as it becomes established. Also, air and soil temperatures need to be warm enough for root growth, so it’s not good to lay sod in winter.

Published: 10/4/2008 1:38 PM

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