Jennifer Schultz Nelson
Extension Educator, Horticulture
Don't let this weather fool you. This is not your "normal" August. Typically in mid-August our office fields calls on plants stressed by hot dry weather. This year, we continue to see examples in August of plants that have been adversely affected by too much water during the growing season.
It's hard to discuss water-saving methods in the garden given the more than adequate rainfall this year, but Mother Nature has a way of getting even-- not every August will be this moderate in temperature.
Fresh water is one of earth's most precious commodities. It is estimated that only one one-hundredth of the earth's water supply is considered easily accessible for human use. Despite this, it is easy to take water availability for granted in daily life. Water is as close as the nearest faucet or spigot for many people in the U.S.
Last summer many local cities and towns imposed voluntary or required water restrictions on outdoor water usage. Many people saw first hand how much water their landscapes required, as plants suffered during the watering restrictions.
It is possible to create a landscape that requires little to no supplemental water through the growing season, even in the hottest driest periods. This is sometimes referred to as xeriscaping. The term Xeriscape™ was coined and later trademarked by Denver Water, the water department in Denver, Colorado back in 1978. Xeriscape™ combines the Greek word "xeros" meaning dry, with "landscape". Some people fear that gardening without watering limits you to cacti and the occasional rock, but fear not! -- there are many other options.
It may be possible for you to cut your garden's water consumption significantly by changing how you water rather than choosing new plants. This would be a great place to start in creating a "water-wise" garden.
Soil affects how plants use water, because the particles that make up soil are different sizes and water flows through these particles at different rates. Sandy soils are filled with large particles with lots of space around them. Water flows quickly around these large particles, and the soil dries out quickly. Clay soils are filled with very tiny particles that have little space surrounding them. Water has difficulty flowing around these tiny particles, and the soil tends to not drain well, and during dry times it is hard as a rock.
The solution to either situation is to add organic matter. Organic matter such as composted manure, composted yard waste, or shredded leaves will improve the texture of any soil, and provide water-holding capacity that is just right for plants. Having soil that holds the appropriate amount of moisture will decrease the need for frequent watering.
Another method you can try is using mulch. Mulch is great for suppressing weed growth, but it also slows water evaporation from the soil. Organic mulches, like shredded bark, leaves, newspaper and grass clippings will retain some water themselves. Keep mulch to about two inches deep around your plants. Be careful not to mound mulch at the base of plants, as this can encourage pests and disease.
A method that I have used in my vegetable garden is drip irrigation. Someday I hope to have this in place in my flower beds as well. In a drip irrigation system, over 90% of the water flowing actually reaches the plants. Compare this to a traditional lawn sprinkler, and only 50 to 70% of the water flowing through it actually reaches the plants. The rest is lost to evaporation.
My system is very simple and was fairly easy to set up. Basically, there is one half inch plastic tubing that attaches to our garden hose, and one quarter inch tubing that feeds off that tubing. At the end of the one quarter inch tubing, emitters are attached. Emitters allow water to flow at different gallons per hour (GPH), depending on the ones chosen. For example, in my vegetable garden, I have a 2 GPH emitter on each of my tomato plants. If I turn the system on for an hour, I know that each tomato should receive two gallons of water.
There are some emitters that spray over a small area rather than at the base of an individual plant. The emitters I placed near our green beans hit the base of several plants at once.
I have found drip irrigation parts at various area stores. A starter kit with enough tubing and emitters for an "average" garden bed (coverage depends on how many plants you are trying to water) costs about $25-$30. Keep your eyes open for end-of-season clearances this time of year.
A piece of advice that will go a long way in designing a water-wise garden is "put the right plant in the right place". It may seem too simple, but I think that's the beauty of this advice. All plants have an environment they're suited for, if you put them outside of that environment, they won't perform as well, and might even die.
In light of discussing water needs, a plant that needs consistently moist soil will probably not do well in a dry sandy location-- unless you are paying close attention and watering frequently. Take that same plant and put it in a spot in your yard that has adequate moisture without extra watering, and you just created less work for you and less water waste in your garden.
If you are ready to add some plants with low water requirements to your garden, consider native plants which are adapted to the weather in this area. Or look for plants which are not native, but are native to areas with climates similar to ours.
Another idea in choosing plants with water conservation in mind is to group plants with high water needs closest to the house, and those requiring less water further out in the landscape. I like this idea because it means you aren't stuck hauling hoses or watering cans across your yard as much.
Keep in mind too that even plants that are touted as not needing much water typically need supplemental watering until they become established. A little extra work when first planted is a small price to pay for a lower maintenance plant and a lower water bill in the long run.