Washington State University Extension

Garden Tips

Archive for March 2010


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Plant breeders must be busy folks. Every year brand new annual flowers are introduced to home gardeners. Want to know what’s new this year?

As usual, there are some new introductions of Wave petunias. Gardeners who know me, know I’m crazy about Wave petunias. It’s so exciting when there is a new Wave to talk about. This year Burgundy Star is being introduced as the first star patterned member of the Easy Wave family. Burgundy Star is a bi-color of rich burgundy and white in a star-pattern. Plum Vein is the first Easy Wave with lavender flowers and dark plum-violet blooms. Easy Waves have a mounded-spreading growth habit with a height of 6 to 12 inches and a width of 30 to 39 inches.

Denim is the name for the newest member of the Shock Wave petunia family. The Shock Waves also have a mounded-spreading habit, growing to a height of 10 inches and a width of 36 inches. Early in the season the flowers of Denim are a dark blue-purple and change to a lighter blue to lavender-silver when the weather turns very hot and sunny.

Over the last several years I’ve come to adore Profusion zinnias almost as much as Wave petunias. Parks Seed is introducing Profusion Yellow, the newest member of the Profusion family with sunny yellow 2-inch daisy-like flowers. Plants grow to a height of 12 to 15 inches. Tolerant of both heat and drought, Profusion Yellow performs all season long, just like the other members of the Profusion family

I’m partial to Wave petunias, but Supertunias also have a reputation for loving the sun, as well as tolerating both heat and drought. In fact, the newest Supertunia, Pretty Much Picasso, grows when it has water and flowers when stressed by dry conditions. Here’s a petunia that performs well in landscape situations even when you’re trying to conserve water. In addition, Pretty Much Picasso has interesting flowers that are violet-purple-pink with lime green edges. Plants grow up to a foot tall and three feet wide.

Pretty Much Picasso would look good planted in a container with the newest ornamental sweet potato vine, Illusion Midnight Lace, with its deep dark purple-black deeply cut lacy leaves. The plant is vigorous and trailing, working well in large containers and as a ground cover. Illusion

Emerald Lace is its twin with with chartreuse deeply cut lacy leaves.

Two new zinnias were selected among the 2010 winning picks of the All American Selections.

One of these is Double Zahara Cherry, a cross between two different zinnia species. The result is a zinnia that’s heat tolerant and resistant to powdery mildew and leaf spot disease. The plant grows to 12 inches tall and wide with 2.5 inch fully double cherry flowers. Double Zahara Fire is a similar zinnia growing a couple of inches taller with 2.5 inch fully double fiery orange-red flowers.

These are just a few of the annuals that you’ll find when browsing through the seed catalogs and in the garden store this spring.

Published: 2/20/2010 1:46 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Something you may not know about me is that I’m part Irish, so I’d like to take this week to talk about growing potatoes. After all, the devastation of the potato harvests by a fungal blight led to the death of at least a million of the Irish people and the emigration of a million more. Definitely not cheery chatter, but fitting to recognize “spuds” as part of the Irish American heritage.

While Idaho is often recognized for its potatoes, Washington comes in a very close second to Idaho in potato production. What makes Washington and Idaho great potato production areas? The Washington State Potato Commission notes that russet potatoes grow so well here because of “favorable soil, day length, a 150-plus day growing season, proper temperatures during the growing season, warm days and cools nights during the bulking season, and controlled irrigation.”

With such an abundance of potatoes grown in our region, why would gardeners want to grow potatoes in their gardens? Commercial production is focused on growing commercial varieties, especially those favored by the food processing industry. There are many wonderful specialty varieties that aren’t readily available in the grocery store or that come at a premium price at local farmers’ markets. My favorites are some of the red potatoes, but some like fingerling potatoes or other heirloom varieties. I also think potatoes are fun and easy to grow.

Potatoes do best when planted early, about the time of the last frost date which is May 1st for our area. Potatoes are an early crop, forming tubers the best when soil temperatures are between 60 and 70 degrees. Tubers won’t develop well when soil temperatures are above 80 degrees.

Purchase “certified disease free” potato seed. Novices need to know that “potato seed” isn’t like bean seed or carrot seed. Potato seed is either small potatoes or 2 to 2.5 ounce chunks of the tuber containing one or more “eyes” or buds.

Before planting, till the soil deeply working in some type of quality organic matter, such as compost. Plant the seed pieces about 4 to 6 inches deep and 12 inches apart with rows 2 to 3 feet apart. When the plants are 8 to 10 inches tall, you should “hill” your potatoes. This is done by mounding the soil eight inches tall and a foot wide along the bases of the plants in the row. This prevents the tops of the potato tubers from exposure to sunlight which turns the skin green, making it bitter and poisonous to eat. Hilling also keeps the tubers cooler.

One of the critical factors in growing potatoes successfully is watering . You must keep the soil evenly moist. Irregular soil moisture conditions alternating from too wet and then too dry will result in knobby potatoes.

Here are several garden mail-order companies that specialize in potatoes. Check them out and get your potatoes ordered today.

Irish Eyes-Garden City Seeds in Ellensburg, WA: or call (509) 964-7000

Ronnigers Potato Farm LLC in Austin, CO: or call: (877) 204-8704

Potato Garden in Austin, CO: or call: 970-835-4500

Published: 3/20/2010 11:26 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Go. Go. Go. Stop. The very mild spring weather that we have experienced over the last month has plants and gardeners getting ready to go, but some recent cold nights may be putting the breaks on a bit. I’m always wary of early warm spring weather, because weather has a way of changing very abruptly. However, the tenuous forecast for the remainder of the month indicates daytime temperatures in the 60 degree range and nighttime lows above freezing. Based on this forecast, gardeners can get going.

Crabgrass Preventer or Pre-emergent Herbicide: The time to apply these “preventer” type materials is before crabgrass germinates. When crabgrass germinates is dependent upon the temperature of the top inch of soil. Germination occurs when the daytime and nighttime soil temperature reaches 55 to 60 degrees and stays there for about a week.

We often tell gardeners to wait until area Forsythia is in bloom for several weeks before applying a preventer material. However, this bright yellow flowering shrub is what’s called a phenological indicator. It blooms when soil temperatures are approaching that 60 degree range. An inexpensive soil thermometer is a more accurate way to determine if it’s “time”.

So why do we dither so much over when it’s time to apply “crabgrass preventers” every spring? University research indicates that crabgrass may start germinating when the soil warms up to 60 degrees, but it can continue to germinate over the next 12 weeks. If you apply your preventer material too early, it may dissipate before all the crabgrass germinates later in the summer.

Forsythia is also an indicator that it’s time to prune your roses. Local Tri-City Rosarians recommend pruning your roses when Forsythia is in bloom. Now is the time. As you prune, you may find that last December’s severe cold spell caused some injury to your roses. Prune canes back to where you find white centers. Remove portions of canes where the centers are brown, tan or beige.

It’s warming up fast, so if you haven’t planted your early cool season crops, you’d better get going. Gardeners often like to plant their peas on St. Patrick’s Day. Peas will germinate as soon as the daytime temperature reaches 45 degrees, but grow best when temperatures are between 50 and 60 degrees. If you haven’t planted your peas, lettuce, and cool season spinach, you should. Also, get ready to plant your broccoli, cabbage, cauliflower, carrots and beets soon.

Now is also the time to cut back your ornamental grasses that have died back to the ground over the winter. Cut the grasses back to about 4 to 6 inches from the ground. Some of the cool season grasses have already started to grow, so be careful not to cut back into new green growth. Start by tying all the stems in the clump together using rope or a bungee cord. Use a hedge trimmer or small chain saw to cut across a clump of tough- stemmed grasses. Soft or fine stemmed grasses can be cut with a serrated knife or hand sickle. Clean up evergreen grasses, by gently combing the grass with your fingers using a gloved hand.

So for now it’s go, go, go, unless it snows.

Published: 3/13/2010 11:23 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Do you like rhubarb? No, I’m not asking if you find rhubarb cuisine tasty, I’m asking if you like it as a garden ornamental? Culinary considerations aside, rhubarb is quite a beautiful perennial with large dark green leaves and brightly colored leaf stalks. You might want to consider adding it to your landscape or garden just for its exotic appearance. Hygienist

As a perennial plant, rhubarb is a cool season perennial, needing temperatures below 40 degrees Fahrenheit to break the plant’s dormancy and allow new growth to begin in the spring. It also prefers moderate temperatures with summer temperatures averaging less than 75 degrees Fahrenheit.

Obviously, our average summer temperatures are well above 75 degrees, but local gardeners still grow rhubarb quite successfully. I would recommend a cooler spot in the garden where the plant will get some shade during summer afternoons. Since rhubarb grows best in well-drained soil that’s high in organic matter, it’s a good idea to mix quality compost, peat moss, or coconut coir into the area before planting.

Rhubarb is planted from crowns or divisions from other plants, not from seed. Often a gardening friend that is thinning out their crowded plant will be happy to give you a division from theirs. You can also purchase them from garden stores or mail order catalogs. If you desire one with very red stalks, consider that there are different named cultivars or varieties of rhubarb. If you’re looking for red, stay away from ‘Victoria’ that has green stalks with only slight red shading.

Spring is the best time to purchase and plant rhubarb crowns. When you receive your crown, plant it as soon as possible to prevent it from drying out. Start by working the soil to a depth of 8 to 10 inches, mixing in 3 to 4 inches of organic matter along with some complete fertilizer such as 16-16-16. Once ready, plant the crown so that it’s only about two inches deep. Gently firm the soil and then thoroughly water it in. After the new shoots poke their heads above the soil, mulch the plant with compost.

Rhubarb likes water, so keep the soil moderately moist and be sure to keep the plant mulched. However, don’t overdo it with the water, since excess soil moisture can lead to crown rot. A large vigorous plant, rhubarb also needs regular fertilization. Apply garden fertilizer both in the early spring just before new grow begins and again in mid-summer. After your rhubarb plant matures, it may occasionally send up flower stalks. These are best removed when they appear so that the plant can focus its energy on growing leaves instead of flowering and seed production.

If your palate is pleased by this decorative vegetable, you should refrain from harvesting any stalks the first year and only a few the second year after planting. Hopefully, by the third year it will be well established and growing well enough that you’ll be able to harvest a bumper crop. Harvest stalks by grasping them near the base and then pulling and twisting gently so they snap off at the base. Don’t cut out the stalks or the flower stalk.

Within three to five years, your rhubarb plant may become crowded and need dividing. Then you can share some with a friend who’s looking for some.

Important Note: If you don’t know it already, only the leaf stalks of rhubarb are edible. The leaves contain oxalic acid and are considered quite poisonous.

Published: 3/6/2010 10:58 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

“Perennials and shrubs are in. Garden divas are out.” That is according to the Garden Media Group, a division of a marketing firm that specializes in promoting new lawn and garden plants and products. It’s their business to know the newest trends in gardening.

One new trend that the Garden Media Group predicts is a focus on sustainable landscapes, including small shrubs, easy-care flowering perennials, native plants, and water conservation. Gardeners are moving away from high-maintenance garden prima donnas and gravitating towards plants that don’t require extra care. Plants need to be both pest and drought resistant.

Over the last several years gardeners have embraced low maintenance ornamental grasses, but they’re now looking to add more color and texture to their gardens and landscapes. Garden prima donnas need not apply. Low maintenance, durable tough native perennials are stepping up in a big way. Plant breeders are working with a variety of flowering natives to produce hybrids that add colorful excitement to the garden, but bring with them the toughness of the original natives.

Coneflowers are one example of these improved natives. Plant breeders have developed new coneflower hybrids by breeding the native purple coneflower, Echinacea purpurea, to other native Echinacea species. The results are coneflowers that come in various colors including pink, white, yellow, orange and even green. There are new coneflower varieties of different sizes and with different flower forms, including double and double-decker flowers.

This year’s new coneflower introductions include Flamethrower with large orange flowers, Firebird with orange-red shuttlecock-like flowers, Gum Drop with candy pink double flowers with large pom-pom centers, Maui Sunshine with large bright yellow flowers and flashy orange center cones, and Little Angel with lots of white flowers produced on a smaller, compact plants. Most of the new coneflowers are also fragrant. Other natives that have the attention of plant breeders include Agastache, Coreopsis, Gaillardia, Monarda, Penstemon, Salvia, and more.

Plant breeders have also been giving attention to the demand for easy care shrubs that fit better in the smaller landscapes of today’s yards. One of these that you’ll be seeing soon is a sweet little compact lilac called Bloomerang. Not only does it stay small and compact, only growing to a height of four to five feet, but it also has fragrant purple-pink flowers that appear in spring and again from mid-summer to fall. The leaves are also more diminutive than traditional lilacs.

Just a few of these new smaller shrubs are Fine Wine, a two to four foot tall Weigela with purple leaves and hot pink flowers; Show Off, a compact Forsythia that grows from three to six feet tall, has dark green leaves and abundant large, bright yellow flowers early in the spring; Lo & Behold Blue Chip, a purple-blue flowered miniature butterfly bush that forms a tidy mound that’s only 24 to 30 inches tall; and Lil’ Miss Sunshine, a diminutive two to three feet tall Caryopteris with sunny yellow leaves and true blue flowers in late summer.

Other garden trend watchers are the Garden Writers of America. They survey American consumers several times a year to find out what interests American gardeners the most. They found that in addition to sustainable gardens and landscapes, gardeners are also interested in conserving water, growing native plants, gardening without pesticides, and growing more edibles.

The Garden Writers’ surveys also reveal the most popular source of gardening information is not the internet or gardening magazines, but friends.

Published: 2/27/2010 10:46 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Whew, I know it’s a lot of work, but there’s just two more steps before you can plant your veggie garden. Once you’re finished working up the soil, your final steps before planting are raking and setting up irrigation. Use a garden rake to make the soil surface level and smooth for planting. Raking with the tines pointed down helps you remove any rocks or debris that came to the surface with tilling. Use the rake with the tines pointed upwards to assist you in creating an even surface.

As soon as you plant, seeds will need water for germination and plants will need water to grow. In our dry region, gardeners can’t rely on natural precipitation to provide anywhere near enough water. That means irrigation of some sort is required. While this is the point when you set up your irrigation system, it should be considered much earlier in the planning stages.

There are numerous options, but drip irrigation, drip tape, or soaker hose are three good options. All three help conserve water and minimize both weed growth and disease problems. Of course, sprinkler irrigation is also a viable option.

Soaker hoses are hoses with tiny holes from which water trickles out or hoses with porous walls from which water oozes out. These are less expensive than a drip system, pretty simple to set up, and work best in row or bed situations where plants are close together. They’re also easier to flush out and clean if you’re using irrigation water.

Drip systems are more flexible and work well if you have a complicated garden plan with plants at varying spacings or locations. If managed properly, they’re also the best at conserving water. However, drip systems tend to be more expensive to set up and must be managed very carefully. Drip emitters have a tendency to become plugged, especially when using irrigation water. Careful attention is needed to prevent plant stress that can result when emitters become plugged. Whatever system you chose, set it up and make sure it works before planting.

Yippee! Finally we’re ready to plant. Many novice gardeners make a trip to the garden store for transplants. The convenience of garden store transplants can’t be beat. They’re definitely an advantage in getting a head start on the season with warm-season crops like tomatoes and peppers. Crops that do well as transplants include certain warm -season crops, like tomatoes, peppers, hot peppers and eggplants. Some cool-season veggies, also do well as transplants, like cauliflower, cabbage, and broccoli

However, there are some crops that perform best when grown directly from seed. Cool season crops that are best from seed include lettuce, peas, spinach, Swiss chard, radishes and carrots. Warm season crops that do best when directly seeded in soil include corn, beans, cucumbers, squash, pumpkins, melons, and watermelon.

Check the seed packet directions for recommended time of planting, depth of planting, and spacing of seedlings. Seed packets and seed catalogs provide you with lots of valuable gardening information. Be sure to thin young seedlings to the recommended spacing so they’ll have plenty of room to grow.

Getting a new garden started is a lot of work, but it’s worth it when you see your baby green plants start emerging from the soil. It’s even better when you begin harvesting the veggies that you grew in your own garden.

Published: 2/13/2010 10:38 AM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Now what? You’ve decided where to place your garden and how big it will be, plus you’ve already worked up the soil. The next steps are preparing the soil and fertilizing.

STEP FOUR – PREPARING THE SOIL: Few gardeners are satisfied with their soil. Complaints range from soil that’s too heavy and poorly drained to soil that’s too sandy and dry. The solution for both these problems is the addition of stable organic matter. Good quality compost is one of the easiest ways to add organic matter to your soil. The compost should be dark and crumbly, with no identifiable chunks of bark, twigs, pieces of wood, or other items. You can usually purchase compost in bulk from a local garden center.

How much is needed? You should never add more than one-third by volume of relatively stable organic matter to your soil. That means if you’re working the soil to a depth of six inches, don’t add more than two inches of organic matter. Peat moss and coconut coir are two other types of stable organic matter that are readily available to gardeners, but both are considerably more expensive than compost. Some gardeners don’t like to use peat because there are environmental concerns about harvesting it from bog ecosystems in Canada. However, the Canadian peat industry is well regulated and harvesting is balanced with restoration practices to protect this natural resource.

If you have concerns about using peat moss, look for coconut coir. Coconut coir is a renewable byproduct of the coconut processing industry and comes from the coconut husk. It’s sold in dry compressed “bricks.” Look for the fine type, not the coarse, chunky kind, to add to your soil.

To thoroughly mix organic matter into the soil, use a spading fork. This is hard work. If you find the task too backbreaking, consider renting a rototiller. It will also come in handy for working fertilizer into the soil, which is the next step.

STEP FIVE -FERTILIZING: If you’re starting a garden in a brand new spot and adding organic matter, you’ll also want to add some fertilizer. An excellent organic fertilizer is rabbit manure. This is the perfect manure to till into the soil. It’s easy to transport and not as smelly as most other manures. You may be able to find free bunny poop advertised on-line or in newspaper ads. Start with about 20 to 30 gallons of rabbit manure per 100 square feet of garden area. Other manures will work, but they’re often bulkier and smellier, plus some will contain weed seeds that are still viable even after spending time in an animal’s digestive system.

Another great source of nitrogen and organic matter for the garden is alfalfa pellets. Alfalfa pellets are dried, ground alfalfa pressed into pellet form. Look for them at a farm and garden store. For adding to the garden soil, use only plain pellets without any additives. Spread about two to three pounds of pellets per 100 square feet of garden area and till them into the soil before planting.

I’m a big fan of bunny poop and alfalfa pellets, but there are also plenty of commercial boxed organic or inorganic fertilizers available that will help your garden grow.

Published: 2/6/2010 10:26 AM



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