Fruitless olive is an evergreen shade tree with silvery-green leaves that has no flowers or olives, making it non-allergic and virtually litter-free. Here’s everything you need to know about planting and caring for this twist on a classic Mediterranean tree.
Fruitless olive tree (Olea europaea ‘Wilsonii‘) is a hybrid of the ancient olive trees native to the Mediterranean. It is usually grown as a multi-trunk tree with gray bark, thin gray-green leaves, and insignificant sterile flowers.
While the fruitless olive tree looks like it could have been taken straight from the hills of Tuscany, this resilient tree thrives in the extreme temperatures, harsh sun, and poor rocky soil of the desert southwest.
You might be wondering why there is a need for a “fruitless” olive tree. After all, olive trees have been cultivated for literally thousands of years.
Olive trees have been banned for decades in Pima County (Tucson), Clark County (Las Vegas), and several municipalities in the Phoenix area due to their being highly allergenic.
Other complaints about olive trees include that uncollected olives make a mess and stain pavement, and that heaving roots can be a trip hazard.
In response, non-allergenic fruitless olive trees were developed.
Why I Like This Plant
- Hardy evergreen shade tree that looks beautiful all year
- Thrives in extreme environments
- Attractive silver-green leaves and gray bark
- Non-allergenic, virtually litter-free
Optimal Growing Conditions
If you’re thinking of adding a fruitless olive 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
Fruitless olive should be grown in USDA Hardiness Zones 9 – 11. It’s very resilient to high temperatures and can withstand temperatures down to 15℉.
Sun Exposure
Fruitless olive trees thrive in full sun, including reflected heat, but will also accept some shade.
Size and Growth Rate
Fruitless olive is considered a slow to moderate grower. When mature, you can expect your tree to be approximately 25 feet high and wide.
Soil
While not a southwest native, fruitless olive is quite happy in our poor, rocky, alkaline soil, provided it’s well-draining. If it stays too wet, it’s prone to root rot.
Other Location Considerations
Fruitless olive is a garden friendly tree. It has no thorns and is non-toxic so you can feel comfortable planting it where it might come in contact with people and pets. Except for the occasional errant leaf, it’s virtually litter-free, making it a good choice to put near a pool.
Fruitless Olive:
The Essentials
| Common Name | Fruitless olive |
| Scientific Name | Olea europaea ‘Wilsonii’ |
| Origin | Mediterranean region |
| Plant Type | Evergreen tree |
| USDA Zones | Zones 9 – 11 |
| Cold Hardiness | To 15℉ |
| Flower Color | Inconspicuous, sterile |
| Flower Season | Spring |
| Mature Size | 25’ high x 25’ wide |
| Growth Rate | Slow to moderate |
| Sun Tolerance | Full sun, reflected heat |
| Water Needs | Low |
| Pests & Diseases | Root rot if overwatered |
| Garden Friendly | No thorns, non-toxic, non-allergenic |
| Wildlife | Deer resistant |
How to Plant
The rule of thumb when planting any shrub or tree in the desert is to dig a hole three times as wide as the root ball but no deeper. Amending the soil is not recommended. Counterintuitively, backfilling with the same native soil you just dug up helps your plant develop a stronger root system.
When to Plant
The best time to plant fruitless olive is in the fall. This gives your tree three seasons to grow roots and get established before the following summer.
The second best time is in spring, the earlier the better. This still gives your plant time to get established before the intense heat of June arrives.
How to Care for Fruitless Olive Tree
Whether you’ve recently planted a new olive tree or have an existing one in your yard, here’s how to take care of it to keep it healthy and looking its best.
How to Water New Plants
Once you’ve got your tree planted, watering is your most immediate concern.
Here is the recommended watering schedule for new trees.
| Weeks 1 & 2 | Every 3 – 4 days |
| Weeks 3 & 4 | Every 6 – 7 days |
| Weeks 5 & 6 | Every 7 – 10 days |
| Weeks 7 & 8 | Every 10 – 14 days |
After week 8, gradually extend the time between waterings.
How to Water Established Plants
As your tree becomes established, there are two watering factors to consider.
- First is how often to water. This will vary with the seasons.
- Second is how much water to give your tree with each watering. This depends on its current size.
To determine the ideal watering schedule for any desert tree, you’ll find everything you need to know, including easy-to-use charts, at How to Water Desert Trees: How Often? How Much?
Should You Fertilize?
There is no need to fertilize fruitless olive. They’re accustomed to growing in poor, rocky soil and don’t mind the alkaline soils of the desert southwest.
How to Prune
Fruitless olive tree grows naturally a multi-trunk tree, but some nurseries carry specimens that have been trained to form a single-trunk tree.
The University of California recommends that you not prune olive trees until they are four years old. But as it matures, it will need occasional pruning to keep its shape.
If you aren’t sure about how to create the shape, I strongly urge you to hire a professional. Hiring an arborist (not a so-called “landscaper”) to get your tree off to the right start is an excellent investment that will result in a beautiful tree that will grace your yard for decades to come.
You can expect to see suckers growing at the base that will need to be pruned. This is a straightforward task you can do whenever they appear. Snap them off with your fingers as soon as they appear will result in fewer scars on the trunk.
Fun Fact!
DNA analysis reveals that humans started growing domestic olive
trees in the Mediterranean between 6,000 and 8,000 years ago.
Fruitless Olive Tree Cultivars
Fruitless olive tree ‘Wilsonii’ is not the only fruitless olive cultivar. Other hybrids include:
- Majestic Beauty® Fruitless Olive (Olea europaea ‘Monher’), a patented hybrid by Monrovia
- Swan Hill Olives® Tree (Olea europaea ‘Swan Hill’), a patented hybrid that was discovered growing near the town of Swan Hill, Australia
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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.
