Creosote bush, the resinous shrub that gives desert rain its smell, can be grown from its own seed with a hot-water soak and patience rather than special equipment.1University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush In the wild, though, its seedlings only show up in unusually wet summers, so a gardener is essentially recreating a rare good year in a pot.2Environmental Data Initiative. Rainfall Manipulation Study Vegetation Data from the Chihuahuan Desert Grassland and Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (2003-2011) The hard part is less getting a seed to sprout than keeping a young plant alive through drought and rot until it roots into the ground.
Preparing Creosote Seeds Before Sowing
Creosote seed comes inside fuzzy, pea-sized capsules that split into segments, each holding a seed.3University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush Before you soak, pick through the capsules and set aside any that are crushed, moldy, or visibly chewed, since a damaged capsule is unlikely to hold sound seed. A fair share of seed won’t sprout even when handled well, so soak more capsules than the number of plants you want.
Place the capsules in a shallow pan, cover them with boiling water, and leave them to soak overnight.4University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush Pour boiling water over the seeds and let it cool; don’t simmer them on the stove, since continuous boiling can cook the seed and kill it. The soaking leaches out substances in the seed covering that hold back sprouting. In desert shrubs, soaking for about 15 hours helped germination in some species but not others, so the soak is a helpful step, not a guarantee.5Agronomy Journal. Seed Treatment of Mojave Desert Shrubs
Removing the hull from the seed segments improved sprouting more than soaking intact segments in one test.6Journal of the American Society for Horticultural Science. Evaluation of Three Growth Curve Models for Germination Data Analysis When segments are left whole, about 9 hours of soaking worked best in that test.7Journal of the American Society for Horticultural Science. Evaluation of Three Growth Curve Models for Germination Data Analysis Other treatments tried on desert shrubs, such as ethylene gas, 4 hours of dry heat at 60°C (140°F), or nicking or roughing the seed coat, each helped only one species.8Agronomy Journal. Seed Treatment of Mojave Desert Shrubs
To hull, rub the soaked segments between your fingers or on a fine sieve to loosen the fuzzy coat. Work gently so the small seed inside isn’t crushed, and sow right after soaking or hulling rather than letting the seeds dry again. If you hull some segments and soak others whole, label the pots by treatment and note the sowing date, so you can see later which method worked and whether a slow batch is normal.
Sowing and the Conditions That Make Seeds Sprout
Sow 5 to 7 soaked seeds in each pot.9University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush Once they’re up, thin to one seedling per pot.10University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush
Use a gritty mix, such as half sand or pumice and half potting soil. Avoid rich, peaty mixes that stay wet, and choose pots with drainage holes. Deeper pots suit this deep-rooted shrub.
Creosote seeds sprouted about twice as well in darkness as in light.11Fire Effects Information System. Larrea tridentata Cover seeds with a thin layer of sand or grit rather than leaving them on the surface, about as deep as the seed segment is thick. A deeply buried seed may not reach the surface, and grit is less likely than fine potting soil to form a crust the tiny sprouts must push through. Water gently from above with a fine spray, or from below by setting the pot in a shallow tray, so the seeds aren’t washed out or packed down.
The best single temperature for sprouting was about 23°C (73°F).12Fire Effects Information System. Larrea tridentata A warm room or late-spring outdoor shade works.13Revista de la Facultad de Ciencias Agrarias. Germination temperatures and seed dormancy of two Larrea species (Zygophyllaceae) from the Monte Desert, Argentina14Revista de la Facultad de Ciencias Agrarias. Germination temperatures and seed dormancy of two Larrea species (Zygophyllaceae) from the Monte Desert, Argentina
Moisture matters too. In the wild, seed batches sprouted best, 20 to 60%, after moderate seasonal rain of about 80 to 150 mm (3 to 6 inches).15Ecology. Effects of Rainfall and Temperature on the Distribution and Behavior of Larrea Tridentata (Creosote‐Bush) in the Mojave Desert of Nevada Both drier and much wetter seasons dropped sprouting to 0 to 20%.16Ecology. Effects of Rainfall and Temperature on the Distribution and Behavior of Larrea Tridentata (Creosote‐Bush) in the Mojave Desert of Nevada Keep the mix evenly moist but never soggy.
In warmth, sprouts usually appear within a couple of weeks. If nothing appears after several weeks, re-soak a fresh batch.
Keeping Seedlings Alive
Drought caused most seedling losses in field studies, with a fungal rot that collapses young stems also killing some.17New Mexico State University Agricultural Experiment Station. Life-History Characteristics of the Creosotebush, Larrea tridentata Very wet weather favored infection, sometimes killing seedlings before they even emerged.18New Mexico State University Agricultural Experiment Station. Life-History Characteristics of the Creosotebush, Larrea tridentata Let the surface dry between waterings and give good airflow.
Seedling rot shows up as stems that pinch and darken at the soil line, and seedlings that flop over suddenly. Remove affected seedlings and cut back on water. Use clean pots and fresh mix next time.
To judge when to water, push a finger into the mix to the first knuckle and water only when that depth feels dry. When you do water, soak the pot until water runs out the bottom, then let it drain fully rather than giving frequent small sips. Small pots dry out fast in strong sun and heat, so check them more often in hot spells and less often in cool or cloudy weather.
When several seeds come up in one pot, wait until the seedlings have a few true leaves and keep the sturdiest. Snip the extras at the soil line with small scissors rather than pulling them, because pulling can tear the roots of the one you’re keeping. Thinning also opens up airflow around the stems, which helps with rot.
Creosote grows best in full sun.19Gardenia. Larrea tridentata Seedlings raised indoors, though, usually need gradual exposure to full sun over about 10 days.20Seed to Fork. Hardening Off Schedule Some growers find seedlings raised under lights with UV need little or no hardening off.21AlboPepper. How to Harden Off Seedlings or Should You?
For the routine, start with an hour or two of morning sun and add time each day over the 10 days. Bring pots in during wind or heat waves. If leaves look pale or scorched, step back a day.
Planting Out and Getting Established
Grow seedlings only until their roots hold the soil together, then plant directly into loosened native soil.22University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush Creosote forms deep roots, and young plants move best before roots circle the pot.
Plant in a mild season, such as spring or early fall, rather than at the height of summer heat. Avoid planting just before a hard freeze, because a small new plant has less protection than an established shrub. A mild season gives the roots time to grow down before the first long hot, dry stretch.
Slide the plant out of its pot gently and avoid pulling on the stem, which is thin on a young plant. If the soil mass holds together, keep it intact, since creosote doesn’t like its roots disturbed. If a few roots are circling the bottom, loosen them lightly with your fingers so they point outward and downward.
Dig a hole wider than the pot and loosen the surrounding soil. Set the plant at the same depth it grew in the pot, water deeply once, then let the soil dry. A wire cage protects it from rabbits.
The plant needs well-draining, dry soil that is low in organic matter and not compacted.23Garden Oracle. Creosote Bush It tolerates pH from 6.6 to 9.0, neutral to strongly alkaline.24Garden Oracle. Creosote Bush Typical desert soils suit it, so skip compost and fertilizer. It does best in rocky, sandy, or gravelly ground.25Gardenia. Larrea tridentata
Irrigate occasionally for one or two years until the plant is established.26University of Arizona Cooperative Extension. Backyard Gardener #95 Creosote Bush After that it’s drought tolerant, needing only about monthly water in summer for best looks.27Gardenia. Larrea tridentata Growth is slow, often several years to a sizable shrub. Deep, infrequent watering trains roots downward, while frequent shallow watering keeps them near the surface.
Collecting and Storing Your Own Seed
Collect seed from late spring through summer.28SFGate. How to Grow Creosote Bushes from Seeds Sonoran Desert plants shed most seed in summer, while Chihuahuan Desert plants hold seed until fall.29Fire Effects Information System. Larrea tridentata In Sonoran areas, don’t wait, because a late visit can find the branches empty. In Chihuahuan areas you have more time.
Capsules are ready when they turn brittle and begin splitting along their seams.30Blossomdale. Creosote Bush Seeds Planting Guide Left too long, seeds blow away or fall.31Blossomdale. Creosote Bush Seeds Planting Guide Unripe capsules are green or soft and feel moist, while ripe ones are dry, fuzzy, and tan to brownish. One that crumbles or splits apart when you roll it between your fingers is likely ready. A single bush can hold both green and ripe capsules at once, so you may need to return for later ones.
In the field, choose healthy, heavily fruiting bushes and shake branches over a bag or tray. Sort out empty or insect-damaged capsules. Only take from your own or permitted land.
Dry seeds thoroughly, then store them cool and dry until late winter.32SFGate. How to Grow Creosote Bushes from Seeds Germination dropped as storage temperature rose,33Fire Effects Information System. Larrea tridentata so an airtight jar in the refrigerator is a good choice.34Blossomdale. Creosote Bush Seeds Planting Guide
Why Other Plants Struggle Near Creosote
Creosote resin contains a strong compound35Digital Desert. How to Grow a Creosote Bush From Seed that can hold back other plants’ sprouting and root growth,36Digital Desert. How to Grow a Creosote Bush From Seed and soil beneath creosote bushes carries more of it.37Digital Desert. How to Grow a Creosote Bush From Seed Avoid sowing other seeds right under a mature bush. Wet summers that bring up creosote seedlings also boost grasses, so keep weeds and grass away from young plants.38Environmental Data Initiative. Rainfall Manipulation Study Vegetation Data from the Chihuahuan Desert Grassland and Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (2003-2011)
When planning a bed, give the shrub space and plant companions near its drip edge rather than under it. Give each plant room for its roots to spread without running into the creosote’s root zone. Tough natives such as desert marigold or brittlebush make good partners, and plants that already grow near creosote in the wild are most likely to tolerate its neighborhood. Mulch with gravel instead of bark, and expect bare ground under the shrub.