Actual size and flowering may vary slightly based on season.
Fern of the Desert
Fern of the Desert is a native tree from the mountains southeast of Tucson, grown for its soft, fern-like leaves and light, filtered shade. It usually reaches about 15 to 20 feet tall and about as wide, as a single or multi-trunk tree. In late spring it fills with creamy white puffball flowers that draw bees and butterflies. It has no thorns and gets by on low water once it is rooted in.
Best for: light, filtered shade over smaller plants, a soft-textured accent or background screen, and native gardens for bees, butterflies and birds.
The fine, fern-like leaves cast light, filtered shade rather than dense shade. That suits shading smaller plants underneath, and the tree fits as an accent in compact spaces.
The late spring flowers are a nectar source for bees and butterflies, and the leaves feed orange sulfur caterpillars. The tree draws birds too.
Left alone it grows as a large, spreading shrub, or it can be trained into a small single or multi-trunk tree. Either form works as a background screen or a specimen.
Spent flowers and flat brown seed pods drop heavily from late spring into fall, so plan for cleanup near pools and patios. Frost around 25°F can damage leaves and tips. It also suckers at the base.
- Closer planting8 ft apart
- Wider planting12 ft apart
For the first two weeks, water a new tree every 1 to 2 days in summer, or every 3 to 4 days in cooler months. Ease to about weekly in summer by the second month, and keep up deep, regular soaks for its first 3 years. Once rooted, soak it 2 to 3 feet deep at the canopy edge about every 2 to 3 weeks in summer and about once a month in winter.
Take off the nursery stake at planting, and stake only if the tree cannot stand on its own or sits in a windy spot. Use two stakes outside the root ball and soft, wide ties that let the trunk sway. Remove them after about a year.
Cut suckers from the base and train it to a few main trunks. Never take more than a quarter of the leaves in a year, and do not strip the inside branches bare. Finish any thinning before monsoon season starts in mid-June.
Frost damage starts around 25°F. A frosted tree usually pushes a big flush of new growth once it warms up, so wait for that before cutting.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
How big does Fern of the Desert get?
Usually about 15 to 20 feet tall and about as wide, and the spread is often wider than the height. Some trees stay closer to 10 to 15 feet.
How fast does it grow?
It grows at a slow to moderate pace. If you want faster growth, give it extra water in the hot season.
How far apart should I plant Fern of the Desert?
Plant them about 8 to 12 feet apart, center to center, for a group or screen. A single tree spreads 15 to 20 feet wide, so leave that much open space.
Is Fern of the Desert native to Arizona?
Yes. It grows wild in the Rincon Mountains southeast of Tucson and south into Sonora, Mexico.
Does Fern of the Desert have thorns?
No. Fern of the Desert is a thornless tree with soft, fern-like leaves.
Why is my Fern of the Desert dropping leaves in spring?
This is a normal spring leaf drop, so there is nothing to fix. The old leaves turn yellow and fall, and new leaves replace them quickly before it flowers.
How cold hardy is it?
Leaves and branch tips can take frost damage around 25°F. After frost damage it tends to push out a big flush of new growth.
When does it bloom?
Late spring into early summer, with small, fragrant, creamy white puffball flowers in clusters at the branch tips.
Is Fern of the Desert messy?
Yes, it drops a fair amount. Spent flowers carpet the ground in May and June, then flat brown seed pods drop later in summer and into fall.
Can I plant it near my pool?
It drops a lot of flowers and seed pods, so it is not the best pick right at the pool edge. Give it some distance to cut down on cleanup.
How much water does it need?
It needs low water once it is rooted in. Give it a deep soak about once or twice a month in summer, and a little more if you want faster growth.
How should I prune it?
It suckers heavily at the base and wants to grow as a big shrub. Train it early as a tree with a few main trunks, and remove suckers as they come up.
Fern of the Desert for sale in Arizona, delivered to you
Fern of the Desert is a thornless native tree with fine, fern-like leaves and creamy white puffball flowers in late spring. It gives light, filtered shade on low water and feeds bees and butterflies. Below is what to expect in a Valley yard, from size and spacing to water, frost, pruning and bloom.
Sourced from trusted Arizona growers and delivered directly to your door, job site, or property. We deliver across the Valley and to nearby towns, and quote delivery anywhere else in Arizona.
Fern of the Desert, a native Arizona tree
Fern of the Desert grows wild in the Rincon Mountains southeast of Tucson and south into Sonora, Mexico. It is sold under a few botanical names, including Lysiloma watsonii and Lysiloma thornberi, and also goes by feather bush.
How big does Fern of the Desert get?
Plan for about 15 to 20 feet tall and about as wide, often wider than tall. It grows at a slow to moderate pace, and faster with extra summer water.
How far apart do you plant Fern of the Desert?
In a group or screen, plant about 8 to 12 feet apart center to center. A single tree needs about 15 to 20 feet of room for its spreading canopy.
How often do you water Fern of the Desert?
It is a low water tree once it is rooted in. A deep soak about once or twice a month in summer is a common schedule. Extra water in the hot season speeds up growth.
Fern of the Desert frost and spring leaf drop
The leaves turn yellow and drop in spring, then new ones fill in quickly before bloom. Frost around 25°F can damage leaves and branch tips, and the tree tends to regrow quickly afterward.
Fern of the Desert flowers and wildlife
Creamy white puffball flowers open in late spring into early summer. They feed bees and butterflies, and the leaves feed orange sulfur caterpillars. The tree draws birds too.
Pruning Fern of the Desert
Left alone it grows as a big, suckering shrub. Early training shapes it into a single or multi-trunk tree. Remove suckers at the base as they come up.
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