Mexican Fence Post
The Mexican Fence Post (Pachycereus marginatus) cactus makes a frequent appearance in upscale desert landscapes. It’s also one of our most popular plants.
Quickly reaching over 10 feet tall, this cactus demands attention with its height and geometric shape, whether growing in clusters along a wall or on its own as a main focal point.
If you're seeking to add vertical interest to your landscape with a tall and elegant cactus, then the Mexican Fence Post may be just what you're looking for.
Botanical name: Pachycereus marginatus
Other names: Mexican Fencepost, Fence Post Cactus
Mexican Fence Post (Pachycereus marginatus) for sale at our nursery
TABLE OF CONTENTS
Mexican Fence Post Appearance
Pastel-toned dark green stems with 5, 6, or 7 white ribs covered in short spines.
Mexican Fence Post blooms in the spring, and its flowers are pink, white, yellow, and light green.
The height when mature is typically about 20 feet.
Mexican Fence Post Landscaping Tips
Plant in an area that has vertical clearance. It requires effort to transplant this spiny and tall cactus should it outgrow its original spot.
If planting the cactus in a line, for example, along a wall, give it enough distance between the plants so that offsets have room to grow from the sides.
Because the spines on the Mexican Fence Post are short, and the cactus grows upwards neatly (minimal curves and no arms branching out from the sides), this cactus can be planted near an area with high foot traffic.
Multiple Mexican Fence Post cacti in a landscape make a bold statement. We recommend accompanying this tall and rigid cactus with softer looking plants such as Mexican grass tree, lantanas, or periwinkles.
Mexican Fence Post Origin
Central Mexico, in regions that enjoy a mostly temperate climate with very warm and humid summers.
Detailed look at the Mexican Fence Post
Mexican Fence Post Care
Caring for Mexican Fence Post is very easy, especially if you've cared for a cactus before.
Soil: Loose, well draining soil that is moderately fertile. Cactus or succulent soil mixes work well.
Temperature: Can withstand temperatures slightly below frost (frost = 32 degrees Fahrenheit) for a brief period of time.
Water: Occasional, deep watering. Allow the soil to completely dry out between waterings. Either use a moisture meter or stick your finger through the soil to gauge the moisture level. It’s better to err on the side of underwatering than overwatering.
Minimal water in the winter, when the Mexican Fence Post is dormant. More water in the summer during the growing season.
Sun: Full sun to partial shade
Mexican Fence Post Problems
Pests: Mexican Fence Post has minimal pests, which are usually scales. To remove scales, pick them off or use horticultural oil or insecticidal soap. Horticultural oil will kill both crawlers and adults with direct contact. Insecticidal soap is better used to target only the crawlers. Whenever using any kind of pesticide, be aware that it can damage the plant if the temperatures are in the 80s or above.
Fungal diseases from root rot, dry rot, and harsh weather conditions.
Signs of overwatering: Yellowing, drooping, squishy texture (especially an the bottom of the cactus)
Signs of too little water: Shriveling, drying skin, fading color
Signs of too much sun: Burning, scarring
Signs of too little sun: Etiolation, discoloring.
Mexican Fence Post Propagation
The Fence Post cactus produces generous offsets- small, baby stems- from the main plant. If you'd like to transplant them or gift these to someone, you can cut them off using a blade. Allow the offset to dry so that the cut can be healed, which reduces the possibility of rot.
Once a callus has formed, usually after a few days, plant the offset, and water it.
FAQ
How fast does Mexican fence post grow?
In the Palm Springs area, you can expect it to grow about 1 to 1.5 feet a year until it reaches maturity. In more temperate regions, it grows about 2 feet a year until maturity.
How much does a Mexican fence post cost?
At our nursery, Mexican Fence Post costs $15 for a 1-gallon container, $45 for a 5-gallon container, and $50 per foot for a 15-gallon container size and above.
Prices are subject to change. Please contact us for the most up-to-date information on pricing. We may have larger sizes available. We provide installation services locally at a separate cost.
How tall do Mexican fence posts get?
It depends on the location and care it receives, but in the Southwest, Mexican Fence Post can grow to more than 20 feet tall. In its native environment, it can grow to more than twice that height!
Why is my fence post cactus turning yellow?
The most likely reasons are overwatering or nutrient deficiency.
Summary
| SIZE (H X W) | 20 feet |
|---|---|
| FLOWER COLOR | Pink, White, Yellow |
| FLOWER SEASON | Spring |
| EXPOSURE | Full Sun to Partial Sun |
| WATER | Low |
| GROWTH RATE | Moderate to Fast |
| HARDINESS | 32º F, USDA Zone 9 |
| PRUNING | None |