Water-Wise Landscapes

During the hottest summer months, our lawns and gardens face a number of environmental challenges which threaten their health and beauty. Wilting and discoloration of lawns and foliage is a common example, as are flowers dropping buds, or tomatoes succumbing to blossom-end rot. And yet these symptoms also herald additional complications, as voracious insect pests and fungal diseases find an easy prey in plants under stress. The root of the problem is soil moisture and whether plants are getting enough to drink during cloudless, 90 degree days.

The solution to dry soils and drought, however, is not simply to run a hose and run up a huge water bill. Watering is very often the most wasteful and expensive of solutions -- with improper watering or overwatering leading to even more short and long-term problems for the landscape. To keep your corner of the globe green, it is best to become water-wise.

Liquid Lawn Care

Lawns are the dominant part of most landscapes. Grass is easy to put in, especially over a large area, but keeping grass green and lush is another story. Lawns are notorious water hogs, with most doting homeowners applying much more water than a lawn really needs, often squandering as much as 100,000 gallons on a typical quarter-acre suburban lot. Fortunately, there are a number of simple water-wise practices that can actually improve the health of your lawn, while saving money, time, and tens of thousands of gallons of precious water.

Stop watering. Although it sounds like lawn care heresy, most grasses (except bluegrass) can safely be allowed to enter a period of dormancy during the driest part of the summer. In fact, dormancy is a natural mechanism to help grass survive drought and heat. Your lawn will recover with the return of rain and cooler temperatures.

Stop fertilizing. The worst possible time in the year to apply fertilizer is in the summer. That jolt of nutrient pushes grass plants to grow unsustainably, risking health and vigor, and interrupting root development when it is most needed. Wait until fall before even thinking about fertilizing.

Grasscycle. Let grass clippings remain on the lawn when you mow, and cut your grass no lower than 3 inches. Clippings are over 90 percent water, and, as they filter to the soil surface, they provide a temporary layer of mulch to conserve soil moisture; taller grass also shades the soil, reducing surface heat and evaporation.

Watering do's and don'ts. If you must water, do it right. Water only in the early morning, never during the day or in the evening; improper watering can lead to fungal diseases or scalded foliage. Do not water on windy days, as breezes only hasten evaporation. Do not water driveways, streets or sidewalks; in addition to wasting water, runoff entering stormdrains can elevate stream temperatures and harm or kill sensitive fish and other aquatic life.

Water lawns only when they need it, normally when foliage appears dull, bluish-grey, or when walking on grass leaves footprints. Avoid frequent and shallow waterings which can cause thatch and shallow, drought-sensitive roots. Lawns require about one inch of water, although no more than once a week. To measure, place a flat pan under the sprinkler until one inch of water has accumulated, then move to a new location. Ensure that soil is moistened to a depth of four to six inches by pushing a screwdriver into the ground as your indicator. Turn off your hose if water starts to spill onto paved areas; wait 30 minutes, and resume watering.

The Water-Wise Landscape

As lawns require about five times more water than other plants in the landscape, the best water-wise practice is to reduce the amount of space dedicated to turfgrass, while also improving the quality of the soil and its moisture-holding ability.

Eliminate the competition. Lawns often run right up to and under trees and shrubs. However, grass roots easily "steal" water from these other plants, while still struggling to survive in the shade. Instead of grass, substitute an organic mulch, such as wood chips, shredded leaves or leaf mold, or plant ground covers -- you can even combine the both options for a low-water, low-maintenance, and attractive planting area. [See the posting: Ground Covers: Made in the Shade, August 25, 2007.]

Expand planting beds. Increase privacy and landscape value by developing "planting islands" in your sea of grass. Plant trees and shrubs in spacious, sweeping beds, rather than individually. Existing trees and shrubs can also be linked together as planting islands by adding an additional tree or two and replacing the lawn area between them with mulch or ground covers. In sunnier spots, "mulch islands" can be established, utilizing ornamental grasses, showy perennials, and hardy native plants. Eventually, over a period of time, these individual "islands" can become the dominant landscape feature, with lawn areas now serving as easily-managed green lakes and open spaces among a more natural, graceful, and beautiful setting.

Mass plantings. Similar to planting islands for trees, it is best to mass plants together, rather than spreading them across a broad area. Massed plantings have a stronger visual impact than a row of annuals dotted in front of shrubbery. Moreover, by grouping plants together according to similar water needs, they can be cared for much more easily, and can more readily care for themselves. A thick, established group of plants will keep out weeds and will shade the soil around their root zones, thereby conserving precious moisture and reducing drastic changes in soil temperature.

Xeriscaping. Although xeriscaping (xeros = dry) originally related to landscaping in extremely dry climates, its principles, which include using water-efficient and drought-tolerant plants, fit well with our water-wise goals. For example, using regionally adapted plants, such as the growing variety of natives, ensures that the plant can handle this area's seasonal temperatures and rainfall, along with other environmental and soil conditions. But non-natives can also be used to add color and texture to the garden, especially those which are suited for dry, sunny locations, like many of the Mediterranean herbs: rosemary, thyme, etc. Generally speaking, silver-grey plants, such as Dusty Miller, Artemisia, Santolina, and so, feature foliage which reflect sunlight, thereby keeping the plant cool and reducing water loss. However, xeriscaping does not mean using only colorless plants, Yuccas and Prickly pear cactus -- it does mean using the right plant in the right place. See below.

Mulch, mulch, mulch. Mulching with organic materials is one of the easiest methods for conserving soil moisture and providing long-term soil improvement. Mulches can be placed on soil up to four inches deep, except over shallow-rooted plants like azaleas. After applying mulch, especially when using wood chips or materials which appears dry, it is advisable to water both mulch and plants thoroughly at first. Dry mulch might otherwise keep moisture from percolating into the soil. Woody mulches are best used around permanent plantings, like trees and shrubs, while finer textured mulches, such as untreated grass clippings, compost, shredded leaves and leaf mold, are preferable for tender plantings, such as annual and perennial flowers and vegetables.

Compost, aerating, topdressing. Improving soil quality will also improve its soil retention ability. Garden beds can be amended by adding compost, either by digging it in manually or rototilling it into the soil, which is best done in autumn or early spring. Existing beds can be improved by using compost as a mulch or sidedressing anytime of year. Aerating a lawn allows air to reach grass roots, helps microorganisms break down organic matter to feed the lawn naturally, and facilitates water penetration. Topdressing is the practice of applying compost to the surface of the lawn up to one-half inch deep, increasing the soil's organic content, enhancing earthworm activity, and serving as a mulch to protect shallow grassroots.

Becoming water-wise can be as simple as changing some everyday practices -- or as involved and comprehensive as changing the face of your landscape. Like most endeavors, your success depends upon a program which matches your interests, abilities, and available resources -- although the ultimate goal of the water-wise landscape is to safeguard our existing water resources, and to provide more time for your other interests.

Copyright 2010, Joseph M. Keyser