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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 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



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