Summers are tough for a desert botanist. It pains my heart to look out across both our yard and the open desert and watch the native plants turning brown, dropping their leaves, and shutting down for the summer. I know that these plants have to do this just to survive the coming months of intense sun, 100+ degree heat, and no promise of rain for most of the year. Yes, the scientist in me knows that all these desert plants have adapted to this climate by taking an obligate summer sleep, designed by nature to slip into dormancy for the summer, and that shutting down is what allows them to survive the brutal summers here. But it hurts me, none the less.
Like watching our friends struggle, it’s hard to see desert plants go through long summers with no water, resorting to dropping all their leaves and going dormant during extreme conditions.
This is a strategy used by plants from deserts around the world. When the soil is hot and dry, the plants sleep. When the soil is cool and wet, they wake up and grow. I know that I must resist the urge to keep their soil wet over the summer; I would not be doing them any favor to constantly water them, because soils that are wet when they are hot would only grow harmful bacteria and fungus that cause root rot, and deprive the roots of needed oxygen, especially when soils are hot. I would literally kill my native plants with kindness.
But wait–it’s not the water per se that kills desert plant roots in the summer; it’s continuous water in hot soil that kills them. So what if we could occasionally deliver the water down into a soil depth where the soil isn’t hot? Moisture in cool soil doesn’t grow root pathogens like it does in hot soil. An occasional summer thunderstorm can be a natural occurrence in the desert, and that doesn’t hurt the plants, because it is fleeting moisture, soaked up by roots, and quickly drying out; the soil will not be soaked again for many weeks or months. Infrequent soakings don’t create enough incubation time for big populations of harmful soil microbes to grow and cause root rot.
So here is a strategy to help native and other desert-friendly plants get through summer with less pain for them and for their human garden stewards: during the summer, deliver water deep into the soil occasionally with “deep water stakes”, soaking subterranean soils several feet below the surface where soil temperatures are much lower.
Deep-water stakes are available in 1, 2, and 3-foot lengths to deliver water deep into the ground with no surface evaporation, delivering that water into cooler subterranean soil layers.
We decided to try this method when our 25-year old, 15-foot tall row of sugarbush plants (Rhus ovata) started showing the stress of seven years of severe drought. They have not been on an irrigation system for decades, since they are native to our valley and normally receive adequate moisture from seasonal rains. But seven years of almost no rain was just too much for them. Their leaves turned brownish-black, most with tiny holes like miniature buckshot; whole limbs were dying, and leaves were becoming scarce on the limbs that were surviving. It was grim. These plants had for years formed a thick privacy screen along our property boundary. Now we could see right through the branches.
Deep-water stakes to the rescue! We bought dozens of 2-foot long, hollow plastic watering stakes with holes along the sides, and a pointed end to make installation easy with a rubber mallet or hammer. In some places, our soil was so dry and compacted, we had to soak the soil with water first to pound the stake in.
We installed a stake between each adjacent plant, and one stake on either side of each sugarbush. We were careful to place the stakes under the “dripline” of each plant, the area under the ends of the branches, where the root system is most active and absorbs moisture. The area right next to the crown of the plant, where the stem comes out of the soil, does not have roots that still absorb water; roots near the crown have barked over, providing structure but not absorption. Many plants suffer from fungal rot if the soil near the crown is continually saturated during warm weather.
Sugarbush leaves before and after deep watering.
These watering stakes are not cheap, but we weighed the cost of losing our trees, and watering much more frequently at the surface and possibly still losing the trees, versus the water saved by watering deeply only every few months. We felt the expense was worth it in the long run. You can make your own deep-water sleeves by cutting short sections of PVC drainage pipe, digging holes next to your plant, burying the sleeve under the dripline of the plant, filling it with gravel, placing your irrigation line through one of the holes, and buying a PVC cap to keep dirt and animals out. However, the caps are fairly expensive, and digging the holes to bury the sleeve next to existing plants is very labor-intensive and can damage plant roots. Deep-watering sleeves made of drainage pipe are most practical if they are installed when a new plant is first planted. We also like the ease with which the manufactured stakes can be pulled out by sliding a screwdriver through the top set of holes, pulling the stake out of the ground, and pounding it back in further from the plant’s crown as the plant grows.
Adapting a garden hose to fit into deep water stakes, which are normally designed for 1/4″ irrigation tubing. We place a washer over the opening of the stake whenever the cap is off to keep dirt out of the stake.
The cap of each stake has a small slit to allow placement of a ¼-inch irrigation line into the stake before fitting the cap over the stake. Since we don’t have irrigation to this far section of our yard, we rigged up a hose ending that fits down into the stake (plastic tubing attached with a hose adapter to a garden hose), and watered with our garden hose.
To reduce the end size of your garden hose to fit down into narrow deep-water stakes, buy a screw-on, plastic hose adapter to fit onto a short piece of flexible plastic hose.
We slipped our plastic tubing into the stake, turned on the faucet to a fast drip/slow drizzle, and set a timer for 6 hours per stake. To our amazement, we started to see not just new leaves, but entire new branches growing within two weeks. We did this just once in April, and again in June. We will not water them again until August or September, if we don’t get any monsoonal rains. With ample winter rains, supplemental irrigation won’t be necessary; however, if we have just a small fraction of our normal winter precipitation, as we have had for multiple years in the past, we might try one deep-watering session over the winter. If these plants hadn’t been so stressed from years of drought, they could likely thrive with just one or two deep watering sessions per year. So many new branches have regrown on every plant that we again have a thick privacy screen shielding us from the street. We feel we rescued these beauties from possible death, or at least a fate so unsightly we would have had to cut them back severely and hope for some regrowth next winter.
We will be testing deep-water stakes on some of our other deep-rooted native plants to determine whether an occasional deep, subterranean soaking keeps them from going totally summer dormant. Like they say, we don’t want to fool Mother Nature, but we would like to give our valiant desert native plants a little boost during our new climate regime of hotter and drier days. We will report back on our results.
Until then, remember that occasional deep soakings are better for your desert-adapted plants than frequent, shallow watering. Deep watering teaches plant roots to grow down deep to find moist soils, protecting roots from drying out at the surface.
Privacy screen of mature sugarbushes with new flush of leaves and branches after being watered with deep-water stakes following a seven-year drought that killed off most of the branches and leaves.
Shallow watering teaches roots to stay near the surface to find moisture, but surface soils heat up fast and dry out quickly. There is little protection for shallow roots if the surface soil heats up and dries out. Roots will never learn to go deep if trained to stay shallow—condemning both of you to a schedule of constant irrigation. For desert native plants, frequent summer watering can speed them toward root rot and death. If you can’t resist watering your struggling natives during the summer, make like a summer thunderstorm and put lots of water on them over one or two days, then let the soil dry out completely before creating another “monsoonal storm”.
As we sip wine on our Hobbit Deck at sunset, it makes us smile to look over our 1/2-acre desert garden and see native plants not just surviving this extreme summer heat, but thriving.
P.S. Deep-water stakes are available locally at Cactus Mart in Morongo Valley, Home Depot stores, and online from “Deep Drip Watering Stakes” at www.deepdrip.com.
Placement of 24-inch stakes for trees. Courtesy deepdrip.com
Placement of 14-inch stakes for shrubs. Courtesy deepdrip.com
Prickly Poppy
We have been trained, over generations of time, that whenever we move into an area, we are to remove the native plants growing on our new site and replace them with plants from wherever we were before, or at least with plants we are familiar with. The plants we introduce into our new setting are not necessarily the ones best adapted to that area, but are the ones that have been marketed to us as the industrial standards that are the “right” ones to use. These plants are invariably mass-produced, mass-marketed, and are therefore the plants that we see for sale all around us: available, cheap, and familiar.
If our new place does not support the plants we have been trained to want (due to climate or soils, for instance), we change the place. We remove the native plants (often considered “weeds”), take out the native soil, bring in new soil, install irrigation, and add pesticides and fertilizers so the introduced plants will be able to tolerate a climate they are not naturally adapted to survive.
What we end up with across America are the same plants, with the same look, no matter where we live. What differs is the amount of time and resources spent to keep those plants living in every conceivable climate to which they are subjected. This may achieve a certain aesthetic look, but it is not ecological in any way. Traditional landscape designs often isolate yards and gardens from the natural environment, then drain the surroundings of resources and add nothing back in return (except for tainting the whole setting with toxic chemical fertilizers and pesticides).
Our best approach to landscaping is to select plants appropriate to our place, and not try to change our place to fit inappropriate plants. By selecting plants that have evolved with our region’s climate and soils, we eliminate the need to constantly add resources not supplied naturally by our climate. Plants native to an area evolved to grow and thrive in those local conditions, and do not need the place changed at all to survive. Our native plants need very little care or maintenance and need very little or no added water or soil amendments. We may be surprised to find how many songbirds are attracted to our native yard plantings, and pleased to realize that those songbirds keep pests under control, eliminating the need for pesticides.
Paperbag Bush Flowers
Some of the benefits of landscaping with natives, or “naturescaping”, include low maintenance, little or no watering after establishment, no need for chemical pesticides or fertilizers, less cost to maintain, healthier home-site (no leaching of synthetic pesticides and fertilizers into groundwater), enhanced property value, and providing habitat for songbirds whose populations are dropping dramatically every year due to loss of habitat.
Let’s change our way of thinking: pick the plant that fits the place, and not change the place to fit the plant. Native plants take care of themselves because they evolved to grow naturally in your own back yard. Desert native plants, in particular, thrive in one of the harshest environments on our planet, and should be the first landscape plants invited back into our southwest desert yards.
Inviting Native Plants into Your Yard
Tips on Planting Native Plants
Tips on Watering Native Plants
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.
Chaparral Bush Mallow
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.
Datura
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.
Tips on Planting Native Plants
Tips on Watering Native Plants
Brittlebush in Bloom
- 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).
Inviting Native Plants into Your Yard
Tips on Watering Native 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.
Songbird Cottage Yard
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.
- 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.
Inviting Native Plants into Your Yard
Tips on Planting Native Plants
Nurseries Selling California Native Plants
Native Plants for High-Desert Gardens
