Tips on plant selection and irrigation from the lead horticulturist of the Water Conservation Garden at Red Butte Garden
There has never been a better time to start using less water in your landscape! As the population of the valley grows, water use rates and prices are sure to increase. If you install a low-water garden or landscape you’ll improve the appearance of your property and save money in the long term by simply growing plants appropriate for the local climate. You can rest easily knowing that you’re not using your great grandchildren’s resources just to be in keeping with the neighbors and their chemically saturated, over- watered, ecologically dead but very green lawn.
There are many wonderful water-wise plants you can choose that provide nectar for pollinators, look fantastic in the landscape and require less fertilizer and labor.
Approximately 50% of household water use in Utah goes towards lawns and landscapes. Sadly, much of this goes towards water-hogging plants that refuse to look good no matter how much you water them. Consider the half-burnt Norway maples, whose branches soar above the scorched earth that Salt Lake City residents call lawns. Now imagine a landscape that uses fewer resources, looks beautiful and provides numerous ecological benefits…this could be your new water-wise landscape!
Even if you love your current garden and lawn, there are small steps you can take to conserve water. You don’t need to change out your entire landscape to reap the benefits of water-wise gardening practices.
There can be confusion surrounding the terms used to describe both plants and design styles in low water gardening.
Water-wise: A water-wise plant is one that requires less water than traditional garden plants throughout the growing season. The terms ‘low-water’ or ‘xeric’ can be used to describe these plants as well.
Drought tolerant: A drought tolerant plant is able to survive a period of drought. A drought tolerant plant does not necessarily require less water throughout the growing season in order to thrive.
Xeriscape: A landscape that requires minimal or no irrigation after it is established.
Zeroscape: A misspelling and mispronunciation (and sometimes misinterpretation) of the term “xeriscape.”
The way you water matters
A common limiting factor in convincing people to convert their existing landscape to low-water landscapes is the notion that you’ll have to entirely replace your irrigation system. That can be costly and complicated. Fortunately, you don’t have to completely switch out your irrigation system to accommodate the change in plants and reduce water use.
Significant amounts of water are wasted by improperly managed irrigation systems. The easiest and least expensive way to save water in your landscape is to make sure your irrigation system does not leak, overspray, or that your sprinkler heads produce a fine mist when running. The fine droplets of water often do not reach the ground and simply evaporate before they can be used by the plants. Use a programmable timer with a rain sensor and a soil moisture sensor to avoid watering while it is raining or when the soil is already wet. Provide a consistent watering schedule that is seasonally adjusted. Water at night or in the very early morning (between 10pm and 8am) to reduce water loss through evaporation.
You can also reduce water consumption through the use of large droplet spray heads. Your existing sprinkler heads can be traded out for heads called rotary nozzles which deliver larger sized water droplets. These large droplets reduce the amount water lost through evaporation by up to 60%. The timing of the spinning nozzles on a rotary nozzle head allows for droplets to infiltrate into the soil before more droplets fall in the same spot, this feature can reduce waste from runoff by up to 40%.
Drip irrigation systems provide the largest water savings over time. There are several styles that work well for the home landscape.
Porous pipe or soaker hoses are best for areas where annuals, like vegetable and bedding flowers, are grown. Soaker hoses are placed on the surface and moisten the surface of the soil. This even moisture over the surface aids in germination of seeds as well. Soaker hoses are easily moved aside when required.
Drip irrigation lines with pre-installed emitters (holes) are used at Red Butte Garden, in commercial applications and home landscapes, to great effect. These lines, placed on the surface of the soil, would ideally be covered with mulch. Drip irrigation lines with root intrusion protection and pre-installed emitters can also be buried beneath the soil (up to one inch). Burying the lines keeps the garden looking tidy and increases the longevity of the lines by protecting the plastic from sun damage.
Drip irrigation lines with punch-in emitters are best for shrubby landscapes where a broad application of water across the entire surface of the soil is not desired. Punch-in emitter drip lines are effective when used in landscapes that will ultimately be truly xeric, as they are easily removed after plants are established. Keep in mind that gardens look best when drip lines are either slightly below the surface of the soil or at least covered with mulch so as to not detract from the glorious plants.
One of the few problems with so many kinds drip irrigation is that they don’t not mimic rainfall in its distribution of water over the entire soil surface. Plants from the lowest rainfall regions are adapted to spread their roots shallowly over a very wide area in order to maximize absorption of rainfall. Some Utah native plants do this as well. Keep an eye on your drip irrigation system, regardless of type, to ensure that the entire surface of the soil is wetted each watering and that water is actually getting to where you want it.
Managing runoff from your irrigation system will provide savings as well. Ensure that water is not flowing down the gutter while your sprinklers are running. You may need to adjust the spray pattern on your irrigation heads or add small berms to the landscape to keep water from flowing off into the street. On steep sites, larger berms can be created to keep water in and around the root zones of plants. There are good online resources that can guide you in constructing passive water harvesting elements. The work of Brad Lancaster is particularly inspiring. Adding plants like grasses and sedges as a filtering and soil-catching piece helps control erosion that comes with slopes and runoff issues.
Many low-water plants that thrive in the Salt Lake Valley are adapted to dry summers, so adjust your watering practices accordingly. Regionally native plants get the bulk of their moisture in the winter and spring as well. Replicating, as best you can, the moisture patterns that exist where your plants are from is essential to their survival. However, plants from dry summer climates will still benefit from a few deep soakings, about once every three weeks, over the course of the hot season. This helps keep them looking good and keeps plants from losing their leaves during extremely dry summers.
Proper establishment of new plants in your low-water garden will determine how well they survive the high temperatures and dry conditions of our summers. Deep, regular watering (two or three times per week) is necessary during the establishment phase (approximately two years). Ideally the soil should be moistened to a depth of eight inches with each watering. After plants are established, watering frequency can be reduced.
Improper planting depth and constantly wet conditions around the crown of low-water plants often kills them. Be sure to plant your plants so that the top of the root ball is level with the surrounding soil and that water drains into the soil quickly. Keep mulch away from the stems of plants as well, as this can cause plants to rot and die.
Renovation and design
Low-water gardening can be practiced in any location; however, some sites are better than others. Ideally, your garden site will receive a full day of unobstructed sunlight and be free of large trees which can make establishing a new garden somewhat more difficult. Sunny garden sites allow for more creative and diverse garden designs as there is a richer palette of plants that prefer full sun.
Shady, treed sites can be planted with low-water use plants as well. With shady sites, keep in mind that the existing watering regimen will need to be maintained or even increased to ensure the health of the existing trees. Large trees can be difficult to underplant due to intense competition from tree roots which are often just under the surface of the soil. Disturbing the roots of some trees can cause them to push out a tremendous amount of new root growth which can choke out your new plants. Sloped areas are wonderful sites for low-water gardens, as they provide the well-drained position that many low-water plants desire.
Careful observation of your garden site will help you determine the best locations for your plants. Map your garden for duration and intensity of sunlight, water accumulation, frost pockets and areas warm up first. Use this information to guide your plant choices.
Do you use your lawn? If you don’t spend time on your lawn, consider removing your turf and replacing it with a low water groundcover, drought tolerant sod or garden.
A soil test is recommended as you begin the planning process. Home soil test kits may be purchased at garden centers and, for a fee, samples can be mailed to Utah State University for testing.
Simple home soil tests are helpful as well and cost nothing. A soil test will tell you what type of soil you have and what nutrients you might add in order correct any deficiencies and make your soil more amenable to low-water plants. Incorporating a 1” thick layer of Utelite, pea gravel-sized volcanic cinder or other drainage-improving amendment into your soil is beneficial for clay and poorly drained soils. Generally, soils in the Salt Lake valley are high in clay and can benefit from the addition of materials that improve drainage. In Sandy and Cottonwood Heights soils tend to drain well and few, if any amendments are needed for them to sustain low-water plants.
Take a long, hard look at your landscape and determine what parts of it you like the most and which provide the most benefit. Examine each plant element of your landscape and decide if it’s worth the water you use to keep it alive. It is likely that there is a plant with similar attributes, but lower watering requirements that you can substitute. Often low-water alternatives provide other ecological benefits as well. Sometimes removing a large tree that struggles through summer is a great way to freshen up the look of your home and landscape and provide an opportunity to replace it with something more appropriate.
When designing your low-water garden, use plants that have the same water and light requirements. Grouping plants that have the same requirements reduces labor by allowing the entire garden to be watered at the same rate. This is called hydro-zoning.
The design process can be intimidating and quite involved. If you are overwhelmed by all the options, start small. Choose an area of your garden that is on its own irrigation zone and begin by renovating it as a test plot. Using an area with its own irrigations allows you to reduce the amount water for that area while keeping your thirstier plantings happy as well.
Select plants that are considered water-wise for your region. Keep in mind that the term “water-wise” is often used to describe plants that are well suited to a particular climate, rainfall amount and geographical area.
Native plants, provided they are appropriate for your conditions, are often a good choice. However, not all native Utah plants are low water use plants. Utah natives from riparian zones and high elevations require regular watering and often struggle when grown outside of the conditions they are adapted to.
So many incredible plants are appropriate for use in low-water landscapes! There are flowering perennials that bloom all summer, stunningly bold succulents, shapely shrubs and incredibly tough trees patiently awaiting you at nurseries and local plant sales. Many garden styles can be achieved with low-water plants—you don’t have to limit your design to cactus and gravel.
If designing a new garden is a daunting task, consider hiring a garden designer and also perhaps a landscape company to design, install and maintain your garden. While this may be expensive, doing it right saves you money. Let your chosen designer/landscaper know that you want a low-water landscape! Check your designer’s plant choices to ensure that they are truly low-water plants before approving a design.
Despite some negative preconceptions about water-wise landscapes, they can be lush and diverse places that anyone would love to spend time in. Don’t allow your prejudices to keep you from improving ecological and stylistic aspects of your garden. Visit Red Butte Garden or your local nursery and ask a horticulturist for recommendations.
Fritz Kollmann is the lead horticulturist for the Water Conservation Garden at Red Butte Garden. He designs gardens, works in his own garden and enjoys skateboarding in his spare time.