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May / June 2002 |
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(greyed articles available in printed version - subscribe now!)
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Conserve Water . . . Plan Ahead If water restrictions and hot weather have gotten the best of your landscape in previous years, it is time to make changes. A few simple steps are needed during each season of the year to create a landscape that isn't water wasteful. With careful management, your landscape can be watered once a week or even less without becoming cooked during the hottest and driest months. Begin now by turning off the water. No matter the time of the year, a stressed landscape will begin to show weaknesses that indicate the areas that need work. As plants wilt or become stressed, note the areas or specific plants where the work begins. If irrigated plants are already wilted, look for pest problems. Insect problems are usually discovered on the underside of the leaf. Using magnifying lens will aid in some detective work. If no insects are found on either upper or lower leaf surface, look along the stems toward the base or apex of the plant. Look for small holes in the stem or trunk. Sometimes insects bore into the bark and deposit eggs. As the insect grows, it tunnels into the plant slowly wilting the leaves until the entire branch dies. Disease problems are generally more difficult to analyze. If an entire plant is wilting, this could be due to below-ground insects like nematodes or grubs or a host of disease organisms. If you are unable to decide what is causing the wilt, seek professional help from your county extension service or gardening specialist. Once you have determined that wilting is not caused by insects or disease, you can move along with your water-saving plan. Ridding weeds from the landscape will help reduce the competition for water. Weeds can be thwarted by creating a healthy soil. Mulches and competition from desired plants will eliminate most weeds. Hand weeding can remove the few remaining weeds. With just a few minutes a week, we can pull, sever or cut the root from the soil and eliminate a water waster. Using a preemergent weed killer like corn gluten can stop many weeds in a new or reconditioned landscape. Next water your wilted plants and see how they respond. If the plants perk up with a small amount of supplemental irrigation, then you can almost be certain the problem is with the plant. The solution then becomes how to get the plant to adapt or to decide to replace the plant with one better adapted. Placing the wrong plant in the right place can be the cause of wilt. Some plants require a drink of water daily. While few plants actually conserve water, many plants use water more economically. Finding the right plant for the right spot is always the best answer. Getting any plant to adapt and look good in a drought is difficult. Even native plants wilt during drought. The key is survivability. Having enough subsoil moisture and getting the roots of your landscape into the subsoil is the key to survivability of plants during times of drought. Lightly stressed plants will grow a more aggressive root system if you give the plants only a minimum amount of supplemental water. By identifying each plant as it becomes stressed, we begin to figure out where our efforts are needed first, second, and so on. By applying compost and mulch to the stressed spots in the lawn or landscape, we begin the first step in drought proofing our landscape. If the lawn is the first to stress, find the dry spots and apply a heavier topdressing of compost and mulch to those areas. When possible and/or practical, topdress after aerating the soil. Aerating the soil benefits all lawn grasses. Some landscape beds will also benefit from aeration. Ideally, aerating should be done in the spring and fall. Holes should be made three inches deep or deeper. Use a tool or machine that removes a core of soil, not one that simply pokes a hole in the soil. The holes are then filled with an equal mix of compost, soil and organic fertilizers depending on the soil type. Clay soils may be filled with a compost mix. Sandy soils should be filled with a clay or loam mix. Never cover the ground with topsoil, even if the soil type is sand. If topsoil is added to the landscape to level a lawn, do this in the fall. The use of composted rice hulls is common in areas where rice hulls are available. The compost can be from any source, but organic compost has soil enriching qualities. Non-decomposed materials like crushed leaves, dry grass or bark mulch will not be as useful as compost but are better than leaving an open hole. In the summer, apply a light coating of compost and a heavy layer of mulch. The mulch can be a double ground hardwood or find ground bagged organic mulch. Mulches should not interfere with mowing. Avoid heavy applications of compost in the summer as even organic compost can scorch an already stressed lawn. In the winter, a heavy application of compost and mulch can be applied even to dormant lawns. Actively growing lawns may suffer some winter burn once a hard freeze arrives, but this will not effect next year's growth. The lawn quality will improve. This is one of the benefits of using organic compost and mulches. If the dry spots occur in the landscape beds and not in the lawn, look closely at the depth of the soil in the beds. Plants placed in raised beds with poor soil or very well drained soil can suffer from drought stress. We often build raised beds with well drained soils because we were taught to do that, but when we overwater, the plants do not put down roots to a lower soil layer that has some water holding capacity. By slowly weaning the plant of its frequent watering, we force it to root deeper. This works for lawn grasses too. Watering only when necessary will force a plant to find available water at any depth. Water lawns only after you can see your footsteps in the grass - one hour after you walked on the turf. Adding small amounts of clay and organic matter to the soil will aid in some water retention, but never add a heavy clay layer atop any soil, even sand. Gradual incorporation utilizing the soil's natural organisms to mix the organic matter back into the soil will greatly benefit water retention. This also advances soil tilth. To try to retain every drop of water that falls on your property, allow beds next to the house to be watered naturally. By allowing rainfall from the roof to fall onto the beds, even small drops of rain can be captured. A dense foliage and thick mulch layer will prevent erosion. Some estimates allow for 20% fewer irrigation cycles on homes with no gutters. (Unless, of course, the gutters feed into a rainwater collection system.) Keeping a dense turf will slow rainfall from exiting your property. A dense turf slows runoff by allowing the rain to seep into the soil instead of running into the street. Building small dams of raised beds can also slow the retreat of rainfall from the property. Aeration, compost, and mulches round out the picture of helping the soil become saturated with every rainfall. After identifying dry spots in the landscape and adding compost and mulch, proper fertilization becomes critical. Do not destroy the soil improvements you have just made by applying a commercial grade high nitrogen fertilizer with a weed killer. Organic fertilizers feed the native microflora of the soil Creating a healthy soil to a depth of 30-36 inches will vastly improve the water holding capacity of your landscape. When that is accomplished, a large reservoir of water is available for most of your landscape plants. If you live in a area with shallow soil, build your raised beds of soils with water holding capacity. When you plant a tree or shrub, dig a larger hole than necessary and backfill with soil that has some water retaining qualities. It is also helpful to remember that perennial plants like trees and shrubs will cast off excess leaves in order to survive a drought in nature. Allowing some leaves to naturally fall during stressful weather can be a water saving device that most homeowners overlook. If your plants begin to lose leaves, they are not sick; they are just adjusting to the dry conditions. Judicious pruning can mimic this natural leaf drop. Never shear plants during a drought, but have a professionally carefully remove excessive growth. Finally, when you need to irrigate, water to a depth of six inches or deeper. This is done most effectively by applying a small amount of water to the soil until a small puddle is formed. Allow the puddle to thoroughly seep into the soil. In five minutes or more, water again until the soil puddles. Repeat this until a puddle quickly forms as the soil is wet. This means that the soil profile is saturated. Most perennials and trees will benefit more from this type of watering than from a sprinkler. When a large area needs to be irrigated, however, a low volume, low trajectory sprinkler will work better than a sprinkler that throws water at high pressure over six feet in the air. Hand watering the few remaining shallow rooted plants then becomes less of a chore. Multiple start times on an automated sprinkler system will work the same as the puddling method. Using this method with any sprinkler will insure that less water is wasted and more water goes into the ground where it will be efficiently utilized by the landscape. David Will is owner of Landscape Details and Gottlieb Gardens, a landscape management and consulting company and wholesale nursery in New Braunfels. |