Mexican grass tree is a stunning specimen plant that will be the showpiece of your garden. And it’s as tough as it is beautiful. Here’s everything you need to know about planting and caring for this southwest desert native.
Mexican grass tree (Dasylirion longissimum) is a spectacular accent plant native to parts of the Sonoran and Chihuahuan deserts in northeast Mexico.
The plant’s thin, four foot long leaves are stiff enough to form a symmetrical rosette, but are flexible enough to sway in the breeze.
This slow-growing plant eventually forms a woody trunk, but don’t hold your breath — it can take years.
Another amazing thing that happens with time is that after 7 to 10 years, it will send up a showy flower spike in the spring that can reach 15 to 20 feet.
Unlike agaves, Mexican grass tree does not die after it blooms. In fact, Mexican grass tree can live to be 150 years old! Once it blooms, you can expect that it will continue to bloom occasionally, but not every year.
Mexican grass tree is an extremely low-maintenance plant. It’s not particular about sun exposure, needs little water, and can take intense desert heat and cold down to 15℉.
Mexican grass tree is non-toxic, requires almost no pruning, and produces no obvious litter except when it blooms.
When in bloom, it attracts birds, bees, and butterflies.
Why I Like This Plant
- Dramatic specimen plant
- Looks stunning all year long
- Takes extreme heat and cold
- Needs little water, and rarely needs pruning
- No thorns, no litter, non-allergenic, non-toxic
Things to Watch Out For
Mexican grass tree is fairly friendly for a large succulent. One of its common names, toothless sotol, refers to its not having serrated edges or sharp tips like many other desert plants. However, its edges can be sharp and give you a cut like a paper cut, so you still need to handle with care.
One other thing to watch out for is your pocketbook. These plants are not inexpensive. A decent-sized one can set you back hundreds of dollars.
Optimal Growing Conditions
If you’re thinking of adding a Mexican grass tree to your garden, you need to find a suitable place that will keep your plant healthy and looking good… while minimizing maintenance for you.
Here are the key factors to keep in mind.
Temperature
Mexican grass tree should be grown in USDA Hardiness Zones 7 – 10. It tolerates intense desert heat and is cold-hardy down to 15℉.
Sun Exposure
Mexican grass tree is not fussy about how much sun it receives. It can take full sun and even the reflected heat off a hot wall, but will also do well in part shade.
However, it will benefit from some afternoon shade in extremely hot regions.
Size and Growth Rate
Mexican grass tree is considered a slow-growing plant. A typical mature specimen will reach a size of 10 feet tall by 6 feet wide.
As it grows, it changes form and starts looking less like an agave or ornamental grass and more like a tree. It ultimately gets quite large, so give it plenty of room to grow.
Soil
It’s not particular about soil and grows in any native desert soil, as long as it’s well-draining.
If you plant it in a pot, make sure it has excellent drainage and use specifically formulated cactus soil.
Other Location Considerations
Mexican grass tree is an excellent container plant, provided it’s in a very large container.
It is also an excellent plant for night lighting. One simple spotlight will cast shadows that change the look of your yard at night from boring to spectacular.
Mexican Grass Tree:
The Essentials
| Common Names | Mexican grass tree, toothless sotol |
| Scientific Name | Dasylirion longissimum |
| Origin | Sonoran, Chihuahuan Deserts |
| Plant Type | Grass-like succulent |
| USDA Zones | Zones 7 – 10 |
| Cold Hardiness | To 15℉ |
| Flower Color | Cream |
| Flower Season | Late spring, summer |
| Mature Size | 10′ high x 6’ wide |
| Growth Rate | Slow |
| Sun Tolerance | Full, part, reflected sun |
| Water Needs | Low |
| Pests & Diseases | Root rot if overwatered |
| Garden Friendly | Non toxic, minimal spikiness |
| Wildlife | Attracts birds, butterflies, bees Deer resistant |
How to Plant
Dig a hole as deep as and twice as wide as the nursery container. It’s generally recommended that you not add any soft fill, gravel, or fertilizer, just native soil.
However, good drainage is critical. If you know your soil is slow draining, amend with coarse sand or small gravel until you have a loose, well-drained mix.
Carefully remove the plant from the container, put it in the hole, and press the soil to remove any air pockets.
When to Plant
The best time to plant Mexican grass tree is April or May. Warm soil temperatures encourage root development.
How to Care for Mexican Grass Tree
Whether you’ve recently planted a Mexican grass tree or have an existing plant in your yard, here’s how to take care of it to keep it healthy and looking its best.
How to Water
You’re probably used to giving a plant a good soaking immediately after transplanting, but that isn’t the best practice with desert succulents like Mexican grass tree.
Counterintuitively, it’s best to not water succulents for one to two weeks after planting. Then water once per month spring through fall. No supplemental water is necessary during the winter.
Should You Fertilize?
There is no need to fertilize Mexican grass tree, it will get all the nutrients it needs from the surrounding desert soil. But if you keep it in a pot, fertilize lightly a few times a year when it’s actively growing.
How to Prune
Mexican grass tree should not be pruned, but you may want to remove lower leaves as they die. You can do this any time of year. But you can choose not to trim them and let them form an interesting-looking “grass skirt”. The choice is yours.
The only other pruning task you may need to do is to remove spent flower stalks.
Don’t Confuse Mexican Grass Tree With…
Mexican grass tree is so striking, you’ll know it when you see one, but if you’re looking at pictures, you can see how it could be confused with other Dasylirions or beaked yucca.
There is another plant, Nolina parviflora, that also goes by the same common name. It is a similar-looking plant in many ways, but has thicker leaves and is rarely offered as a landscape plant.
Plant Lover Facts
Dasylirion is a genus of plants in the asparagus family, all native to Mexico, with a few extending into the southwestern United States.
The rather lyrical name comes from the Greek words ‘dasys’, meaning “shaggy” and ‘lirion’ meaning “lily”.
Other common names for Mexican grass tree include toothless sotol, longleaf sotol, and toothless desert spoon.
Dasylirion longissimum and Dasylirion quadrangulatum are often used synonymously. But they are two separate species. According to The Ruth Bancroft Garden, these two plants are indistinguishable… until they’re in bloom. But for landscape purposes, there is no need to know the difference, and you’ll be more likely to find a plant labeled D. longissimum.
Mexican grass tree is dioecious, meaning that male and female flowers appear on separate plants. The male plant produces cream-colored flowers which contain pollen. Once the female plants are pollinated, their flower spikes are covered with dark-red fruits that remain for months. Bees flock to the male flowers to gather pollen and the female flowers for nectar.
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.
Photo Credit
“Dasylirion longissimum” by Megan Hansen is licensed under CC BY 2.0