Inviting Native Desert Plants into Your Yard
First and foremost, planting at the appropriate time (late fall through early spring) is key to survival for desert native plants. This allows the root system to become established during the cool, rainy season, well before the harsh summer months.
It is in our nature to buy bigger plants because we want the end result right now; however, it is better to plant smaller natives because they will not develop a damaged root system from growing too long in the container, and the roots will grow faster in their new home. Deep roots are a critical element in a plant’s drought-tolerance. If a native plant has been kept in a pot too long, the roots will hit the bottom of the pot and start coiling. This can cause long-term damage to the roots, and hamper the tap root from reaching its full potential as a lengthy “straw” penetrating into deep, moist soil.
There is some discussion about whether to use a planting mix, mulch, or neither when planting natives. One thought is that because they are nursery grown, they have been spoiled with optimal care, and to set them out in the world with poor soil conditions from the start would set them back. Once they out-grow the amended soil they are planted in, they will be stronger and better able to continue on their own. As the composted mulch breaks down, the humus it contains binds with soil particles to actually improve drainage conditions over time. This holds true for poorly-draining soils, such as caliche and clay, but granitic and sandy soils are fast-draining naturally, and don’t require amendments to improve drainage.
A second thought is that plants which are native to our “Creosote Bush Scrub” habitat have adapted to so little organic material in the soil, no amendments are needed during planting. While soil amendments may be optional for some of our desert native plants, one plant that seems to hate soil amendments or fertilizer of any kind is creosote. Native plants from other (more moist) California regions seem to tolerate or appreciate some soil amendments during planting; however, native plants from all habitats in the Mojave and Colorado Deserts except streamside or marsh habitats seem to grow best when planted with no added soil amendments or fertilizers. Most desert natives (especially cactus and all succulents like yuccas and nolinas), do best with no added soil amendments. Do not fertilize any desert natives.
Most native species have difficulty becoming established if planted in the heat of summer. The best approach is to postpone planting until late fall. In high desert climates, postpone planting in early fall if temperatures are still warm, as tender new growth encouraged by the warmth may freeze as winter arrives. Later (cooler) fall planting is less likely to encourage new leaf growth before the plant’s first encounter with winter freezes. Early fall plantings are safe in low desert areas, as winter frosts are uncommon.
If you have to install plants in the summer, consider providing temporary shade to native plantings. Use burlap or other mesh cloth supported by stakes on the sunny side of the plant to create a cooler micro-environment. Don’t drape the shade fabric over the plant, as this will create even hotter conditions. Remember, if you wait until the fall or early spring to install native plants, everything is easier for both you and the plants.
How To Plant Natives
- Plant in fall to early spring – avoid planting in summer if at all
- Plant in fall to early spring – avoid planting in summer if at all possible.
- Dig a hole at least twice as wide and half again as deep as the planting container size.
- Pre-irrigate the planting hole so there is adequate moisture around the root system. Fill the hole with water and allow it to drain.
- Remove the plant from its container slowly. Most natives will not be the standard size of a nursery-grown plant. They tend to be smaller and not as established while still in the pot. Place your hand on the soil with your fingers spread around the base of the plant. Turn the container upside down, and with a slight tap on the bottom, the plant should slide out. Keeping both hands on the root ball, place it in the hole.
- Set the plant crown one inch higher than the soil level so that moisture drains away from the stem. Planting too deeply will cause rot.
It is advisable to install a deep-water sleeve (3” x 18” perforated drain pipe) beside the new plant to aid in deep irrigation to establish a deeper root system.
- If you choose to amend the soil, incorporate a well-composed mulch (no manure), and mix it half and half with soil removed from the hole. Back-fill the hole with the pre-mixed soil and mulch. Potting mixes containing synthetic material such as perlite, vermiculite, and supplemental nutrients should be avoided. These materials do nothing to improve soil conditions over time, and do not allow for a smooth transition into the native soil. Keep mulch and excess soil away from the crown.
- For plants larger than 5 gallons, add water into the hole at the same time as you back-fill with soil to eliminate air pockets. Tamp backfill in gently.
- The only time you cannot over-water a native is on the day you plant. Provide ample water to each plant and generous water to an entire bed or area of new plantings.
- Add mulch on the soil surface to hold soil moisture and cool plant roots, but avoid burying trunk or stems. The best mulch to use around most desert plants is rocks or gravel, or even large pieces of driftwood. Desert plants that naturally grow on more shaded north-facing slopes and canyons (holly-leaf cherry, manzanita, scrub oaks, mountain mahogany, sugar bush, etc.), can be mulched with wood chips or chipped bark.
- Many native plants also like to have a rock placed on their south side to help moderate soil temperature and retain moisture.
- Because nursery-grown plants are prone to being chewed by the native animal life, it is advisable to provide a temporary wire enclosure for the first season, or until the plant sends out new growth, at which time you can remove the enclosure (except in extremely dry years, when animals are desperate for food).
Watering Native Desert Plants
Water regularly in cool months; less frequently, but deeply in hot months.
One of the biggest advantages of using California native plants is that you can select plants whose water needs match our climate. California native plants are well adapted to our climate and can tolerate extended periods of heat and drought. Many California natives in the wild experience a drought-induced dormancy in the summer. They simply maintain their size and shape, add very little or no new growth, and sometimes even lose a few leaves toward the end of the season. This is how they “tough it out.” For natives to display such resilience during our long, hot, rainless season, they need to be well-established with extensive, deep root systems. You can help them establish deep roots by irrigating them properly with deep, infrequent watering.
To have well-established plants in the summer, it is best to plant in the fall to spring planting window. Summer is the most difficult season to install native plants in the landscape. Wait until fall if at all possible and you will decrease the amount of irrigation needed to establish native plants over their first few years. You may successfully plant natives any time from fall until spring, but they will require less water to become well-established the earlier they are planted in the fall-to-spring planting window.
How Much Water?
You can kill natives with too much water, especially during summer months. In general, California’s arid natives in both the low and high desert get significant rainfall only during winter rains. To establish a newly-planted native plant, check every 3-4 days, and water regularly whenever the soil in the root zone (about 3-4 inches deep) dries out.
Since moisture retention varies with soil texture, season, and sun-exposure, you will need to establish the frequency at your site by testing the soil around new plantings with your finger or a moisture probe. Branches which shade the root zone and leaf litter or mulch will protect the topsoil from excessive drying, and extend time between watering.
Once established, native plants can usually exist on natural rainfall. In times of drought, during the period before your plant produces new leaves, or if you want to encourage greener growth, extra water can be added safely during the winter and spring, with monthly or bimonthly watering in summer. In the low desert, where winter rainfall is often scarce, some summer watering is usually necessary.
- Water to keep the plant alive, not to make it grow fast. Try to teach the plant to be drought tolerant. Watering less often and more deeply will stimulate roots to grow deeper instead of near the surface where they will be susceptible to drying out.
- Water by hose, drip or low volume sprinkler in early morning. Drip tubing fitted with microspray emitters deliver water in a more natural way (more like rainfall) than drippers. Install two half-spray emitters per plant, at the drip line of the plant (under the outermost ends of branches), each pointing away from the plant. As the plant grows, move the microsprays away from the plant, keeping them at the drip line of the plant. Avoid watering during the heat of the day or at night as this may cause branch die-back or root rot. Remember if water runs off or does not soak in it does not count.
- Water only when the soil in the root zone begins to dry out. Check the root ball 3-4 inches below the surface to see if it is moist; if it is still moist, wait for the root ball at that depth to dry out between watering days. Water enough to thoroughly soak the soil around the plant, and deep enough to reach the bottom of the planting hole. The establishment period for most natives is usually one year. Your soil type will determine how often you water.
- Water regularly in cool months if no rain falls. Water less frequently but deeply in hot months. Desert soils that remain consistently wet during hot summer months are prone to the growth of harmful soil pathogens, bacteria, and fungus, which can cause root rot in native plants and quickly kill them. Remember that our desert native plants have evolved to survive in wet soil when it is cool, and dry soil when it is hot. They are not adapted to survive wet, HOT soils. If you are able to add water only at a depth where the soil remains cool even in the summer (using a deep-water sleeve, with no water moistening the hot surface soils), then you may safely irrigate throughout the summer.
- Avoid watering frequently with small amounts of water (high frequency, short duration). This method only teaches roots to stay at the surface, making them susceptible to the moisture loss of hot, quick-drying surface soils, and compromising any drought-tolerance they are capable of achieving.
- Apply water at a low frequency with long durations to thoroughly soak the soil and allow vital oxygen to re-enter the root zone between watering. Remember, mulch on the surface will preserve soil moisture between watering.
- For best results, avoid using overhead irrigation for long durations (especially in the sun) because prolonged leaf-wetting during the dry season can promote disease.
Once your plants are established you may only need to water them occasionally during dry winters and once a month or less during the dry season—late spring through fall—to keep them looking good. If you must water them, try to simulate a summer thunderstorm: soak the soil well but very infrequently.