May 11, 2013
The activity: Allocating scarce water in your landscape.
Why: Colorado Springs is in the fourth year of a drought. The City Council has issued watering restrictions, and you need a plan to cope with the reduced availability of water.
How: Start by evaluating the irrigation system in your yard. If your sprinklers are inefficient, consider repairs or upgrades to improve the delivery of water to your plants. Consider replacing spray heads with low-pressure rotator heads that deliver water more slowly and create less runoff. Even better, consider a drip system for everything except lawns. For more information, see Fact Sheet 4.722 for sprinkler system inspection and Fact Sheet 4.702 for drip systems at www.ext.colostate.edu/index.html.
Once you've improved irrigation efficiency, then mulch everything except your lawn. Water loss through evaporation can be cut in half by mulching with organic mulches such as wood chips or pine needles. Nonorganic mulches such as gravel concentrate heat, which isn't healthy for your plants.
If you plan to plant this summer, do so as early as possible - May for perennials, shrubs and cold-season crops and mid- to late-May for tender annuals.
Don't over-water just because it is your day.
Even if you follow these steps, it might come to a point when you have to make some hard choices because you can't keep everything healthy. Prioritize according to vegetation type.
Lawns and annual flowers: This is the lowest watering priority in a home landscape due to the ease and cost of replacing a lawn or colorful flower bed relative to other parts of your landscape. It takes less than a season to replace them. If your lawn is Kentucky bluegrass, it will go dormant if not watered and might recover once the weather cools. If it is a fescue lawn, it requires less water. But if the fescue dies, it is unlikely to recover.
If there are sections of your lawn that do not thrive under good conditions, consider replacing those sections with drought-tolerant shrubs and then adding annual flowers in containers to provide color.
Perennial beds: I love perennial flowers, and it pains me to say they're next on the chopping block. Many perennial flowers are quite drought-tolerant and will manage to stay alive to bloom another year even if deprived of water. When you do water your perennial beds, water them slowly and deeply. Do not over-water early in the spring and do not over-fertilize. Adding too much nitrogen by fertilizing encourages foliage growth, which increases the water needed by the plant.
Woody plants: Mature trees and shrubs have a well-established root system that is able to capture available water in the soil, as well as store water. Trunks and branches also can be water reservoirs. Woody plants have a natural ability to create and maintain multiple growing points so they always have a backup plan should drought stress push them into an early dormancy.
Shrubs: These provide structure to the garden, might offer berries and fruit for wildlife and add winter interest to the landscape. Plus, they tend to require less water.
If an established shrub is stressed by drought or heat, it has a lot of potential to rejuvenate. In response to stress, the shrub likely will go into early dormancy or there will be dieback on the upper section. Prune out the dead branches, and there is a high probability the plant will come back next season. Since it takes additional water to establish new shrubs, it is much better to try to keep your shrubs in good shape during the drought than to replace them. They should be watered if possible, and deep soaking is key.
Trees: Mature trees should be your top watering priority. Trees take years to mature and will not show drought stress for several months or years. At that point, the tree will be in serious decline.
Therefore, keep your trees on a regular watering schedule even if you are watering nothing else. An established tree should be watered once a week between April and September. A rule of thumb is to apply 10 gallons for every inch of trunk diameter measured at knee level. The water should be applied slowly around the drip line. New trees need to be watered more frequently, perhaps twice a week, during hot, dry weather.
You can determine whether your tree is fully established by examining the terminal twigs. Look for annual growth at the end of a twig (there will be a circular 'scar ' between each year). In a newly planted tree, that growth will be shorter until the root system establishes. When the prior year's growth length is similar to the pre transplant growth, the tree has established.