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Conserving Water In The Landscape & Garden Part 2

GARDEN TIPS – written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written May 14, 2015

This summer is going to be tough with irrigation water supplies down at least 54% in many areas and our governor declaring a drought in 24 counties. In past weeks we discussed conserving water in our yards and gardens with a focus on sprinkler irrigation, but we can save even more water by employing drip irrigation.

Dr. Troy Peters, WSU Extension Irrigation Specialist, indicates that at their best sprinklers are only 70 per cent efficient in delivering water to the soil where plants need use it. Drip irrigation is 90 to 95 per cent efficient.

If you make the decision to install a drip system to conserve water, you may become overwhelmed with designing the system and deciding what types of drip equipment to use. Thankfully, Dr. Peters authored a publication “Drip Irrigation for the Yard and Garden” which makes it much less of a puzzle for drip irrigation novices. In this easy-to-understand publication Peters discusses drip equipment, system design, and operation. It is available as a free download from the WSU Extension Online Store at:

While drip irrigation is outstanding for conserving water in gardens and landscape beds, it is difficult to employ for watering trees located in lawn areas. Unfortunately, homeowners usually rely on lawn sprinklers to provide for trees’ water needs. Lawn watering, especially the shallow watering practiced by many, does not provide adequate water for established trees located in lawns.

When watering trees, the soil should be moistened to a depth of at least12-18 inches in the tree’s “root zone” where most of the water absorbing roots are located. This root zone is not located close to the trunk of an established tree, it is at the tree’s “dripline” and beyond.

To picture the location of a tree’s dripline, think of a tree as an umbrella. The water absorbing roots are not located near the handle, they are at the edge of the umbrella’s protection and beyond. Peters points out that this active root zone is usually two to three times the diameter of the tree’s crown or “umbrella.”  That is where water should be applied.

Since regular lawn irrigation does not typically apply enough water for trees located in lawns and drip emitters would be impractical, some method is needed for applying water slowly to the root zone. This usually requires hauling out a hose and watering trees individually with a water sprinkler, soaker hose, drip tape, or drip tubing with emitters spaced along the entire line. The goal is to apply the water slowly enough so that it soaks in without running off.

Trees should be deep watered frequently enough to keep the soil in the root zone moist to a depth of 12-18 inches. During the hottest summer weather this can be once a week.

If water becomes extremely limited this summer, you may have to choose which plants in your landscape will get the available irrigation water. I personally would give a higher priority to saving established landscape trees. It is more difficult to replace them due to their size, the cost of removal and replacement, and the time it would take grow new trees.

As summer looms in the near future, now is the time for action. Tune up your irrigation system, water more deeply less frequently, mulch your garden and landscape beds, and consider installing drip irrigation where practical.


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published – OCTOBER 31, 2014


The gardening season has come to what seems like a rather abrupt end, especially after balmy sunny weather just a couple of weeks ago. Now it is time for gardeners like me to evaluate what went well this year and what did not.

My biggest success was with my numerous large annual flower containers. At the beginning of the season I was dreading hand watering these planters every evening all summer long. Plus, going on vacation meant hiring a plant sitter to keep the flowers alive.

Listening to Dr. Troy Peters, WSU Extension Irrigation Specialist, talk about dripline tubing for irrigating raised vegetable garden beds and seeing the same type of product advertised in DripWorks’ ( catalog as part of a deck-garden drip irrigation kit inspired me to try watering my containers with drip irrigation again.

I previously experienced failure when I tried to water the same large pots with single sprinkler- type drip emitters placed in the center of each pot. They worked for a while, but when the plants grew taller they blocked the sprinkler emitters’ spray. After this earlier failure, I continued to laboriously water my pots by hand every summer.

Learning about the dripline products made me anxious to give drip irrigation another try. Rather than buy an on-line kit, I was able to purchase most of the needed supplies from local irrigation supply companies.

Before I go any further let me tell you about “dripline” or “emitter” tubing. It is plastic tubing (1/4 or ½ inch diameter) that is manufactured with hole-like emitters at regular spacings along the line, such as 6, 9, 12, or 18 inches.

The irrigation engineers indicate that dripline with turbulent flow emitters is “self-flushing and clog resistant” if you have a good (at least 200 mesh) filtration system. The other great feature of this special tubing is that the pressure-compensating design allows it to deliver water evenly along the entire length of the tubing.

I selected brown 1/4 inch dripline with emitters spaced at 6-inch intervals. With help, I placed a circle of the dripline on top of the potting mix before I planted my flower transplants. The brown line blends in with the potting mix. We then used 1/4 inch barbed fittings and black 1/4 inch drip tubing to connect the pots to a ½ inch delivery line running along the ground at base of the pots. The ½ inch line was connected to a timer and pressure reducer off of our irrigation water.

I used trial and error to determine how often and how long to run the timer. Once I was able to figure that out, I didn’t have to constantly worry about watering my pots. However, I did check them frequently and adjust the timer for warmer weather through the summer.

The drip system worked well. We were able to go away for a vacation. I did not have the tedious task of watering every day. The flowers flourished. The plants and I were both happy.

Published: 10/30/2014 12:43 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published- JUNE 20, 2014


It is estimated that over 50 percent of the water used by an average household is used for irrigating our lawns, landscape and garden. Luckily for us, we have enough water for irrigation this year. It looked like we might have to tighten our belts in regards to watering when the snowpack was well below normal in early winter. Fortunately, late winter snows in the Cascades saved us, but climatologists predict that our good fortune is not likely to last.

It is time to start learning and practicing water conservation now, so we will be prepared for any water shortages looming in the future. One way to conserve water is simply not to waste it. How often do you see irrigation water running down the street at this time of year? There are easy ways to avoid this wasteful runoff.

One way is to slow down. Often water is being applied faster than it can sink into the soil, especially on sloped areas. A simple solution is to apply the water more slowly in several short runs with a short break in between each application until a total of 1 to 1.5 inches of water is applied. This gives the water a chance to percolate down into the soil instead of running off.

Water only when needed. Often area residents rely on timers to turn water on and off based on a set daily schedule, never adjusting for weather or checking soil moisture to see if the lawn or plants actually need water. This ‘set it and forget it’ practice is easy, but wasteful. Plus, it does not encourage deep root systems or healthy plants.

Dr. Troy Peters, WSU Extension Irrigation Specialist, notes that your lawn and garden do not need the same amount of water in the spring and fall as they do in the hot part of the summer. For example, he indicates lawns in Yakima, WA ‘only use about .25 inch of water per week in April and October, 1.25 inches per week in May and September, 1.6 inches per week in June and August, and a little over 2 inches per week in July.’

If leave your controller programmed on a setting of 15 minutes every day for the entire season it probably means that you are applying too much water in the spring and fall and too little water in the middle of summer. Peters recommends resetting your timer at least once a month to adjust for the changing irrigation needs.

If your soil is a silt-loam, Peters also recommends putting all the water needed during the week on in one weekly irrigation, not just a little bit every day. Peters points out that ‘soil can only hold so much water.’ When you put on more water than the soil can hold, the excess water is wasted. During the summer when more than an inch of water per week is needed, Peters suggests splitting the total and applying half of the water with two separate runs per week if the soil is a silt loam. However, on sandy soils, you will have to irrigate more often, but should try not to irrigate every day if possible.

There are other ways to conserve lawn and garden irrigation water, but trying not to waste it is a good start.

Published: 6/20/2014 11:41 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published- JULY 18, 2014


It’s getting downright ugly out there. I am talking about the brown spots and large areas of lawn turning brown. It is unsightly, but it is not a surprise. There are a variety of possible causes for this blighting of our green grass but watering, other lawn care practices, and weather are at the root of the problem.

Despite the watering wisdom of ‘watering deeply and less frequently,’ most area lawn owners have not opted to follow this sage advice that I offer year after year… after year. I talked a little earlier this season about watering when plants need it, not by relying on a timer that is set at the beginning of the season and never adjusted.

This year we experienced extended cool spring weather. That did not keep the irrigation timers from being set as soon as water was available with the typical 20 minutes per day. Because of the cooler weather, grass remained wet for considerable lengths of time setting up the perfect conditions for damaging lawn fungi to attack.

Pythium may be one of the fungi causing problems. Pythium fungi attack and kill the roots and crown of the grass plants. During cooler weather the disease may start as small yellowish patches that coalesce into larger areas. When it turns warm the disease show up as large areas of wilted and dying turf.

This disease can be avoided with ‘deep, infrequent watering’ and irrigating early in the morning instead of late at night. To reduce spreading the disease, collect and remove grass clippings when you mow. Remove excessive thatch and do not fertilize heavily during warm weather.

Thatch, another topic I have covered numerous times, may also be one of the problems contributing to lawn ugliness. Thatch is an intermingled layer of organic matter that comes from the grass plant itself. It consists of undecomposed grass stem, crown, and root debris. Thatch is not caused by an accumulation of grass clippings as once thought. It results when the grass produces this material faster than it decomposes.

Lawns in our area are predisposed to develop thatch because our soils, especially sandy soils, are generally low in microbial populations responsible for breaking this organic matter down. Plus, most of our area lawns are comprised of Kentucky bluegrass and fine fescue grasses that form more thatch than bunch-type grasses, like turf-type perennial ryegrass.

Many poor lawn care practices encourage the buildup of thatch and discourage microbe populations. Frequent shallow irrigation promotes thatch. Excessive nitrogen fertilization makes grass grow faster and develop thatch at a quicker rate. Infrequent mowing encourages the development of stem tissue and more thatch. Excessive irrigation and compacted soil discourage microbe activity.

The best defense against thatch is good preparation of the soil before seeding or sodding a lawn, followed by sound lawn care practices. This includes deep, infrequent watering; mowing regularly at the recommended height; fertilizing at recommended rates; aerating to relieve soil compaction; and removing thatch when the layer exceeds one-half inch.

Finally, another common cause of large brown spots in lawns during this hot weather is sprinkler coverage. Check how much water is being applied to the brown areas when the sprinklers are on.

Speaking of water, be sure to drink plenty of it when you are gardening outside.

Published: 7/18/2014 11:38 AM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published 1/24/14

I feel a little like Chicken Little, but local gardeners and homeowners should be afraid. This winter has been very dry and long range forecasts are not currently predicting any relief in sight , but optimistic climatologists say things could change. We=ll see.

Right now snowpack in the Olympics is at 26 per cent of normal and the Cascade watersheds are at or below 50 per cent of normal. This situation has been set up by a winter drought situation in all of Washington with precipitation for first three months of winter at only 55 to 65 per cent of normal. USDA=s Natural Resources Conservation Service predicts that our stream flows in spring and summer will be at 60 to 80 per cent of normal.

What that means for us gardeners is that irrigation water is likely to be in short supply during the coming growing season. Now is the time to start planning on how to cope with this impending drought.

1. Currently, local soils are quite dry since we also have experienced less winter precipitation than is normal in our area. (Gray, foggy weather doesn=t add moisture to the soil.) It will be important to get ahead of the game and deep water trees, shrubs, and perennial plants now. Before watering use a shovel to check for a frost layer in the soil that would prevent water from penetrating into the root zone of plants. If a frost layer persists, wait until it disappears and then water your plants.

2. Most vegetable crops need at least one inch of water per week during the growing season. As you are planning your vegetable garden for this coming season, think about what crops you want to plant. To conserve water, avoid wasting space by planting vegetables that take up lots of space, such as sweet corn, vining watermelon, vining winter squash, and peas. Look for bush and compact varieties of squash, cucumbers, melons, and even tomatoes that will take up less area in the garden. If you plant in rows in your garden, move the rows closer together, leaving you with less area that needs watering.

3. Keep weeds in check with frequent light cultivation. Weeds compete with your vegetables and flowering plants for both water and nutrients. Regular, shallow cultivation with a stirrup, scuffle or AHula hoe@ will keep weeds from stealing limited irrigation water. If you don=t have a good hoe, get one now and be ready. I bought the AHula hoe@ a year ago and was amazed at how well it works cutting off young weed seedlings.

4. If your vegetable, perennials, trees, and shrubs are being watered with sprinkler irrigation, consider putting in some type water conserving irrigation system, such as drip tape, soaker hoses, porous wall hoses, or a drip system.

What do you need for drip irrigation? Consult the WSU Extension fact sheet ADrip Irrigation for the Yard and Garden@ (Peters 2011, FS030E) that is available at no charge from WSU Extension at: The author, Dr. Troy Peters, will be just one of the WSU faculty addressing in the Master Gardener during their training program this year. He will discuss AHow You Know When to Water.@ The 15 session Master Gardener training program starts on Tuesday. If you are interested in applying or learning more about the program, call the WSU Extension office at 735-3551 by Monday.

As the growing season approaches, I=ll talk more on saving water in our yards and gardens.

Published: 1/24/2014 1:43 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Despite what may have seemed like a wet winter to us, there are serious concerns regarding the amount of irrigation water available for the coming growing season. This wonderful spring weather that we’re all enjoying has led to early spring runoff that’s exacerbating a lower-than-normal snow pack situation. What that means for local gardeners is that we are probably facing another season that we’ll be worrying about having enough water to keep our lawns, gardens, and landscapes green. Now is a good time to be considering ways to conserve water so we can keep our plants alive… if water becomes scarce.


First, let’s talk about our overall watering practices. Many local gardeners have already started to water lawns and gardens, which is a good idea considering that most area soils are quite dry. However, as nice as the weather has been, it’s not as hot as July or August. There is no need to water with the same frequency that one must follow in mid-summer. If you’re watering every day or every other day…. you’re overwatering or you’re watering incorrectly.

You should be watering based on the weather, the soil type, and the kinds of plants you’re growing. Keep the soil and plant roots moist, but not wet. Plant roots will only grow close to the soil surface, if the only water and air they can get is near the surface. Use this early part of the growing season to “train” roots to grow deeper by watering less frequently and more deeply. It is these deeper roots that will help the plants and turf survive, if water becomes scarce and unavailable on a daily basis.

Go out and check the amount of moisture in the soil around your plants and in your lawn. Use a shovel, hand trowel, or soil probe to see if the soil is moist. It should be moist down to a depth of at least a foot or a foot and a half for trees and shrubs. For lawns it should be moist at least eight inches deep and for gardens down to a foot. Once you have moistened the soil to these depths, you only need to water frequently enough to keep the soil moist to the depth indicated. Allow the top inch or two to dry out before you irrigate again.

The Difference Between Wet and Moist Soil: If you take a handful of soil and it’s just a bunch of mud it’s wet… it’s much too wet! If you take a handful of soil and can get water to drip by squeezing the soil, it’s too wet too. If you take a handful of soil that’s damp and not muddy or drippy, that’s the moisture level you’re aiming for. Wet soils exclude air . Plant roots need air to grow and to function. Avoid irrigating in such a way with either sprinklers or drip irrigation that keeps the soil wet for any length of time. Check the moisture in your soil several hours after you have applied water. Is the soil wet or is it moist?

Now is also good time to check your sprinkler irrigation system. Turn the system on and look for malfunctioning heads that aren’t putting the water where it’s wanted and needed. Watering walkways, driveways, and streets is irresponsible and wasteful. Fix or replace heads that aren’t working correctly. Check your system for uniformity by placing straight-sided cans (soup, tuna, cat food) in various places throughout the spray pattern of the sprinklers. Run the system for five or ten minutes and then check the depth of the water in each of the cans. If you have a lot of water in some cans and very little in others you need to check both your system and the sprinkler heads. In lawns, those areas receiving very little water will show drought stress first and instigate more frequent watering, but it will also mean that the areas already receiving enough water will become overwatered.. This wastes water and it isn’t good for your lawn.


In landscape and garden beds, the use of drip irrigation can drastically reduce the amount of water you use to irrigate your plants, but the system must be designed and managed correctly based on the types of plants, their age, the soil type, and the water source. When drip irrigation was first introduced to farmers and gardeners there weren’t many choices of emitters and tubing available. Now, the choices are mind boggling and a bit confusing. There are some excellent, knowledgeable local irrigation supply companies who can help you design your system and sell you the materials you need… emitters, tubing, filters, and pressure regulators, There are also mail-order companies that offer similar drip irrigation supplies and help with designing your system.

Before shopping for your drip system, make a scale drawing of the garden or landscape bed you want to outfit with drip irrigation.. This drawing should include the location of your water source, any changes in elevation, and the position and type of established or future plants. You should also know the type of soil (sand, loam, or clay), the available water pressure, and the water flow from the faucet. Take this information and your drawing with you when you go shopping for your system.

There are many different types of emitters. When using irrigation water, drip systems can be frustrating because nozzles tend to plug up with silt, seeds, and other debris. That’s why filters are typically used with these systems, but it’s still common for both filters and emitters to become clogged. There are non-plugging emitters available that can be used with coarse screen filters. The engineering of these emitters is ingenious… they have a diaphragm that stretches when pressure builds up behind any particle blocking the opening. Under the pressure, the diaphragm opens enough to allow the particles to be pushed through the opening and then it returns to normal size.

There are also “shrubbler” emitters that are like little sprinklers that squirt out eight fingers of water. They’re adjustable from a basic type of drip up to a 15 inch diameter circle pattern of spray and can put out from 0 to 15 gallons per hour. That allows you to adjust the emitter as a plant grows or as water needs change.

If you have a perennial flower bed, you might want to consider mini-sprinklers for your drip irrigation design. These little fellas act like little sprinkler heads under the relatively low pressures of drip systems, wetting a circular area of the soil. Ein Dor Mini-Sprinklers emit a flat spray pattern of droplets with circular patterns with a radius of 4.5 to 7.5 feet, depending on the selected mini-sprinkler, at PSI’s of 20 to 30. Some of the micro-sprinklers are designed especially for use with trees that need water applied over a wide radius, to moisten the entire root zone.

There are also various types of drip tape or porous wall hose that can be used in gardens or raised beds where plants are grown in rows. They’re especially great for use in veggie gardens. Buried under the soil, the tape lasts over several seasons and the lack of water on the soil surface between the rows cuts down on weed problems.

Take Note: Too many drip systems aren’t utilizing the improved types of emitters. Many simple drip emitters are placed right at the trunk of a tree or shrub. These fail to moisten an adequate area of soil and often lead to collar rot because the soil is kept too wet at the base of the trunk.

You can find a wide variety of mail order irrigation supplies from DripWorks. They can be reached online at www.dripworks,com or by calling them at 1-800-522-3747. They also sell liners, pumps, and filters for creating backyard ponds.

Published: 4/10/2004 2:28 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I live in a neighborhood with very sandy soil and a plethora of new homes. When I see how some folks are watering, I want to walk up and knock on their doors and tell them the right way to water. I’m pretty sure most would find my fervor to conserve water and promote healthier lawns, trees, and shrubs an intrusion… plus there are just too many homes to make door-to-door irrigation education practical. Perhaps if I share it with you, you’ll knock on their doors for me?

1. Despite what you may have been told, you can overwater in this area, even on sandy soils. Saturated soils, especially in places with poor drainage, can lead to root rot and the demise of trees, shrubs, perennials, and annuals. Wet conditions for long periods of time often lead to problems with lawn diseases that would not usually occur here except for the excessively moist conditions created by too frequent or excessive watering.

Frequent or excessive watering also leaches nitrogen out of the root zone of lawns and other plants, especially on sandy soils. Plants need nitrogen for good green growth. As a result of watering too much, you’ll need to apply fertilizer more often to keep your lawns and gardens green. What a waste!

2. For new homeowners, the builder’s contractor who installed your irrigation system and set up the automatic timer is usually not an expert on watering. Their assignment is to make sure that the lawn and any plants that were planted stay green until you move in. Since they can’t be there daily to manage the irrigation, many of them set it up on frequent, long sets to insure drought stress doesn’t occur.

Once you move in, you should learn about your system so you can manage it to meet the needs of your lawn and landscape plants without overwatering. Run your system for a set amount of time. After irrigating, wait several hours and then check the soil moisture in the root zone of plants. For lawns, the soil should be moist to a depth of eight inches; to a depth of one foot for annuals, vegetables, and perennials, and to a depth of about two feet for trees and shrubs. Moisture below these depths is just wasted. You will want to adjust your system to moisten the soil to the needed depths without wasting water. Water again when the soil starts to dry out, not before.

To check soil moisture, use a soil probe which is basically a piece of pipe with a handle and a sharpened tip. Pushed into the ground and removed, the probe brings up a core of soil which can be checked for moisture. (These can be purchased from some irrigation supply companies and in horticultural supply catalogs. ) Lacking a soil probe, you can simply use a trowel to dig down and check the soil.

3. If you want a good looking healthy landscape and turf, you can’t start out with one irrigation timer setting and then forget about it for the rest of the season.. The frequency and length of sets will change from week to week and sometimes from day to day. You must manage any system.

Whether you’re watering lawns or trees, you should be checking your soil moisture on a regular basis and adjusting your system. Try to shift from frequent shallow watering, to less frequent deeper watering. As you shift, check your lawn and plants for signs of wilting or drought stress.

4. Sprinkler irrigation is very handy for lawns, but soaker hoses and drip irrigation are more efficient in applying the deep watering needed for your trees and shrubs. Water for trees and shrubs should be applied where their roots are located. Young trees and shrubs, those planted within in the last two years, should be watered close to their base. This is best accomplished with a soaker hose, even if your trees are located in the lawn. Lawns don’t need and shouldn’t receive the deeper watering recommended for other plants.

Once a tree or shrub becomes established the root system should grow outwards from the trunk if it was planted correctly. As that happens, water should no longer be applied close to the trunk. As a tree becomes established, deep watering should involve moistening the soil to a depth of 12 to 24 inches where the fine water absorbing roots are located. These fine roots are situated at the dripline (the edge of the canopy) outwards from the tree in a circular band. Deep watering established trees once a week is recommended, recently planted trees and shrubs will usually need more frequent irrigation.

5. While over-watering young trees in our area is common, so is under-watering older, established trees. As a rule of thumb a tree with a 6-foot wide canopy should be provided with 26 gallons of water to wet its root zone; one with a 12-foot wide canopy should get 85 gallons, and a big old tree with a 20-foot wide canopy needs 235 gallons. A soaker hose definitely comes in handy in providing these large amounts of water. You can’t rely on the sprinkler system watering your lawn to be giving your trees adequate amounts of water.

Published: 7/26/2008 1:46 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

At this time of year gardeners are anxious to get out in the garden especially when the temperatures climb above 50 degrees during the day. However, our eagerness must be tempered with the realization that it’s still winter. Spring is coming, but it isn’t here quite yet. Nevertheless, there are a few things gardeners can do “out and about” in the yard and garden.

THINGS MAY BE DRY: Even though it seems like we have experienced a fairly wet winter, things may not be as moist as you think. A recent check of the Master Gardener Demonstration Garden compost pile constructed in the fall revealed that it’s very dry under the top layer. When a compost pile is dry, the bacteria, fungi, and little critters that are part of the decay process can’t do their job of breaking down the organic matter.

Check out your pile and add water if it’s dry. Be sure to “turn” or mix the compost while adding water until all the materials are moist. The soil in your yard may be fairly dry too. Dig down several inches and see if the soil is moist or dry. If dry, you will want to water evergreen trees and shrubs right away.

PRUNING: If you have fruit trees that need pruning, now is a great time to get out the loppers and pruning saws. If you are unsure of how to prune your trees to keep them both productive and small enough manage, refer to the Pacific Northwest Extension bulletin “Training and Pruning Your Home Orchard” at .

If your ornamental landscape trees need pruning, it’s also a good time to prune them. Keep in mind that ornamental trees don’t require regular pruning like fruit trees. Ornamental trees should be pruned only for very specific reasons… health, safety, and beauty. Diseased or borer infested wood can be removed at any time. Hazardous branches or limbs that might fall should be removed, as well as branches that interfere with utility lines or views of traffic. (Beware: Branches encroaching utility lines should always be pruned by professionals. Do not try this yourself.)

A poorly shaped tree may benefit from pruning to correct its form. This can include branches that are aren’t evenly spaced, that shade each other, or that are rubbing against each other. If you aren’t sure about how to prune a tree, you may want consult a professional ISA certified arborist to do the job for you, especially if the tree is big. Don’t ever prune a tree just because you think it should be pruned.

If you have roses, you may be tempted to prune them now too, but local rose experts say to wait until the yellow flowering shrub forsythia is in bloom.

DORMANT DISEASE CONTROL: I recently saw a list of late winter chores and it said “late winter is the time to apply dormant oil for control of insects and diseases.” Wrong! Oils are applied to control insects that overwinter on the bark of trees. These are most effective when applied just when the buds start to open. That’s because the insects are also just becoming active at that time. Applied too early the oils won’t be effective and some oils can damage plants if applied too early when temperatures go below freezing soon after the product is applied.

Dormant fungicides ARE applied now to fruit tree s when the buds are just beginning to swell for control of overwintering diseases, such as coryneum blight on apricots and peach leaf curl on peaches. For what materials to use and when to apply them, call the Extension Office at 735-3551 and ask for the Stone Fruit & Nut Pest Management Chart for Central Washington and the Apple & Pear Home Orchard Pest Management Chart for Central Washington . You can also get downloadable copies at

PLANTER COLOR: Time to get rid of the winter worn flowering cabbage, kale, and pansies in your containers. Replace them with colorful primroses and new pansies for some fresh color.

GOT SPRING FEVER? Join the WSU Master Gardeners for Spring Garden Day, a day long learning event next Saturday, March 1st at WSU Tri-Cities. Spring Garden Day offers a terrific keynote speaker and a variety of gardening classes for local gardeners. Classes include Rose Care, Ornamental Grasses, Tree Pruning, Growing Gourds, Growing Lavender, Best Trees for Home Landscapes, and more. The keynote speaker is Mary Robson a garden book author and retired WSU faculty. The cost is $20 per person and you will want to pre-register for this event, since seating is limited. You can get a registration brochure at the WSU Extension office at 5600 West Canal Drive in Kennewick (735-3551). The brochure is also available on line at

Published: 2/23/2008 2:05 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Are you fed up with an ugly lawn? Is your lawn filled with ugly Bermuda grass or bentgrass? Does your lawn seem to have more weeds then good grass? Too thick thatch causing you problems? If you’ve decided to take action, now may be the time to get started.

If you have a lawn filled with tough perennial grassy weeds, August is the best time to kill them out. You do this by treating the entire lawn with glyphosate (known to many as Roundup). This will kill everything, ‘good’ grass and ‘bad’ grass. Wait for several weeks until the grass dies. Before you treat, quit mowing for several weeks, but keep watering. You want the grass to be healthy and growing well so the application of glyphosate will be effective. Since glyphosate is only absorbed by green tissues, the more leaf surface area that’s treated, the more chemical gets into the plant, and the more effective the treatment. After the lawn dies, wait until next spring (early May) to see if anything starts to regrow. If it does, you treat it again with glyphosate and make sure that everything is dead. If so, then you can proceed with your lawn renovation.

You might wonder, ‘Do I really have to go to all this trouble?’ According to Dr. Tom Cook, Associate Professor of Horticulture and Turfgrass Specialist, at Oregon State University, ‘It is almost impossible to successfully renovate a lawn with the goal of producing perfect mono-culture of planted grass. The key is to make sure you kill the existing grasses completely. This cannot be done by a single spray of non-selective herbicide.’

In the spring you can then get started on your new lawn. First mow the grass to the shortest height possible. Rent a dethatching machine and set it at a setting that allows you to barely cut into the soil with the tines, loosening and breaking the soil surface. You need to do this so you will have good contact between the new seed or sod, whichever you select for re-planting your lawn. You’ve made enough passes over the lawn when it looks like bare soil instead of dead lawn.

If the soil in your lawn is compacted, you will also want to rent an aerifying machine and go over the entire lawn several times. Then finally, go over it one more time with the dethatching machine to break up the cores of soil removed by the machine. After all that hard work, apply fertilizer as for a new lawn and then either seed or sod the area.

When thatch is much too thick, it causes problems. These problems often become very obvious at this time of year. Excessive thatch impedes water movement and the thicker the thatch, the greater the problem. During hot weather thick thatch may even dry out a bit and then resist wetting, preventing water getting to the soil and the roots of the turf. As a result, large indistinct areas of turf will become drought stressed, first turning blue-green and then brown. Thatch greater than one-half inch is considered excessive. Thatch that’s one-half inch to an inch thick can usually be effectively removed with a power rake in the spring. The best time to dethatch is when the weather warms up a bit in the spring and before the middle of April.

If the thatch is one to two inches thick, power-raking thoroughly with a dethatching machine could rip out most of the grass and ruin the lawn altogether. In situations like these, you will need to work at it gradually, removing it over the span of several years.

You’d be surprised how thick thatch can become. I’ve even seen thatch layers in area lawns that are five inches or more thick. With extremely excessive thatch, greater than two inches thick, power-raking with a dethatching machine will not take care of the problem. Renovation may be the only sensible option. In these cases, a sod cutter is rented and used to cut off the grass down to the soil. Then you can use the dethatching and aerifying machines as described earlier.

An alternative approach is to first use the sod cutter to cut the grass just below the stolon level, as they do with new sod. Roll up the strips of sod and set it aside, not allowing it to dry out.. Then remove the rest of the thatch, power rake the soil, and relay the sod. This may be worth the effort if you have beautiful grass, but extremely excessive thatch.

Want to know more about thatch… what it is, what causes it, and how to control it? Go to for more information.

HINT: The soil should be slightly moist when you use aerifying or dethatching machines. If not, they both have a tough time penetrating the soil.

If you have a neglected lawn that’s full of broadleaf weeds with sparse turf in areas, you may be able to improve your lawn without the drastic measures needed for complete renovation. Treat for broadleaf weeds this fall in October using an appropriate broadleaf weed lawn herbicide. Fertilize in early September and early November. Dethatch the lawn next spring and seed those areas at one-half the seeding rate recommended for new lawns. Try to match the types of grass in your original lawn, so the new patches don’t stick out like sore thumbs.

GARDEN NOTE: Unfortunately, dry thatch and sod removed from a lawn does not seem to compost well. You are better off disposing of them in some other way.

WHICH IS BETTER SOD OR SEED? Each has its advantages. Seeding is less expensive than sod and it develops a strong initial root system, plus you have more types and cultivars of grass available for planting. However, seeding only works well when done in late summer or mid-spring. This limits when you can sensibly start a lawn from seed. It takes longer to establish a lawn from seed and you need a consistently moist soil once you plant the seed until the grass becomes established. This can take over a month and can be a challenge if weather is extremely warm or windy. Seeded lawns are also very difficult to establish on sloped terrain.

Sod can be installed anytime during the growing season and it establishes rapidly for an almost ‘instant lawn.’ Sod works very well for sloped situations. The main drawbacks of sod are its expense and there is generally less variety in the types of grasses available in sod.

Published: 8/20/2005 11:41 AM


written by Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA Are you old enough to remember when kids took magnifying glasses and used them to focus the sun’s energy in one spot? You could burn a hole in a piece of paper or worse! There’s a myth that persists with some gardeners that watering in the middle of a hot summer day is harmful to plants. The thinking is that water droplets on leaves act like small magnifying lenses intensifying the light and burning the leaf. Not true! Leaf burn or scorch is not related to the time of day you irrigate. More about scorch later… Since midday watering doesn’t cause leaf burn, is it okay to water in the middle of the day? Yes… but it isn’t necessarily the best time of day to water. That’s because it’s hotter in the middle of the day and you lose more water through evaporation than when you water during the cooler parts of the day or night. If you pay for your irrigation water based on the amount you use, then you’re wasting some of your money when you water during the day. However, that may be the only time you have sufficient pressure to run your system. If you ask a horticulturist like me what’s the best time of day to water, we’ll answer, ‘early morning.’ This is because the temperatures are cooler and leaves will dry off fairly quickly as the temperatures warmup. The least desirable time to water is said to be during the evening. Even though the temperatures may be cooler and the loss of water through evaporation is less, the leaves will tend to stay wet for a longer period of time. In regions with high relative humidity, this creates conditions very favorable to many fungal pathogens. In humid climates, evening or night watering should be avoided. In our very arid climate, evening or night watering isn’t considered a problem since leaves will dry off fairly quickly. Hot weather, restricted watering, and low water pressure has some area residents arguing over when they should and shouldn’t water. I suggest you water when your city or irrigation district recommends and when you have adequate pressure. If you have watering restrictions, water carefully and make the most of the water you have available. Watering more deeply less frequently is better than a little water everyday. Make sure you deep water your trees and shrubs at least once a week, moistening the soil to a depth of at least 12 inches. You may need to use soaker hoses to do this. If your system puts out water so quickly that you have water running off rather than soaking into the soil, consider ‘pulsing’ your system. Do this by running your system on each set for a shorter time and stopping before the water runs off. Wait a while to let the water soak in, then run the system again in the same way. Repeat this until you have moistened the soil to 8 inches deep in a lawn and at least 12 inches deep around trees and shrubs. This procedure is especially valuable when you have a sloped area where water tends to run off before it soaks in. Hint: How can you tell if the soil is ‘adequately’ moist to a certain depth? Use a trowel, shovel, or soil sampler to retrieve a portion of the soil at the desired depth. Squeeze it in your hand. If the soil is wet and you have mud or water oozing out between your fingers, it’s too much water. If the soil feels fairly moist and holds it shape when you open your hand, there is enough water. If the soil feels dry and breaks apart easily when you open your hand, it’s too dry. (Coarse sandy soil may fall apart easily even when moist, but will feel moist.) Even if you don’t check the soil there are signs that plants are suffering from a lack of water. Most obvious are leaves that wilt and droop on herbaceous plants… the non-woody annual flowers and vegetables in the garden. They quickly show that they don’t have enough water. Because they have fairly shallow roots, they’ll suffer from drought conditions first. Other possible signs of drought include: – leaves rolling upward or curling – blossom and fruit drop in fruits and vegetables – small size and lack of good flavor in fruits and vegetables – yellowing and browning of leaves, especially along the leaf edges Lawns take on a blue-gray color instead of their usual vibrant green. If you walk on a drought stressed lawn, your footprints won’t spring back and you can see your steps. An inspection of the individual grass plants will show wilted grass leaves that are rolled or folded. Drought stress isn’t as easy to discern on most woody plants. The leaves of some trees and shrubs may wilt, indicating a lack of water, but early signs of drought stress in most trees and shrubs aren’t obvious. The leaves of some trees may turn yellow or develop early fall color. Shedding of yellow and brown leaves can also be a sign of drought stress. However, the most obvious sign of a drought stress problem is leaf scorch. This is where the edges or margins of the leaves turn off-color and then become brown and dry. (On needled evergreens leaf scorch appears as brown needle tips). If the drought is extended or particularly severe, the areas between the leaf veins may also turn brown and dry. Leaf scorch tends to be worse in the outermost and highest parts of the plant and on the side of the plant exposed to heat and drying winds. It’s important to point out that other factors may be at fault when a tree or shrub exhibits leaf scorch. Anything that interferes with the uptake of water may also be at fault. Possible alternate causes of scorch include extremely high temperatures, reflected light and heat, restricted roots, improper planting, root damage, compacted soil, trunk damage, high salt levels in the soil, and even excess soil moisture. Drought stress weakens plants and the effect can have serious implications for their future health. Potential long term effects include increased susceptibility to disease and attack by insect pests, especially borers. Root death that occurs during drought can lead to twig and branch dieback. Drought stressed plants are more susceptible to injury from extremely cold winter temperatures. Repeated or prolonged drought stress can lead to a plant’s death. So quit worrying about the right time of day to water. It’s more important to make sure the plants… flowers, vegetables, lawn, shrubs, and trees… are getting the water they need especially during the hottest part of summer.

Published: 8/13/2005 11:42 AM

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