Actual size and flowering may vary slightly based on season.
Mexican Fencepost
Mexican Fencepost is the column cactus planted in rows as a living fence, the way it is used in Mexico. Its straight, dark green columns are ribbed and lined with neat rows of small spines, and new columns come up from the base instead of growing arms. It usually reaches 10 to 15 feet tall and grows fast for a cactus, about a foot a year. It takes full sun and reflected heat on low water, and makes a bold vertical accent against a wall.
Best for: living fences and screens along walls and lot lines, tall vertical accents against a wall, and hot, low-water spots in full sun.
It gets its name from Mexico, where rows are planted close together, often from cuttings, along roads and property lines. A row along a wall or lot line grows into a tall green barrier as the columns fill in.
It grows straight up and sends new columns from the base instead of growing arms. That adds real height against a tall wall, as a single clump or a small group staggered along the wall.
It takes full sun and the heat reflected off walls. Once rooted in, it gets by on little or no extra water outside long dry spells, and it is low maintenance.
Column tips can get frost damage below about 25°F, so cover them on freeze nights. Cold, wet soil in winter can rot the roots. Newly planted columns can sunburn on the hottest west and southwest sides their first summer. The short spines still prick.
- Living fence row2 ft apart
Wait one to two weeks after planting before the first water. Then water about every other week while nights stay above 60°F. In cooler weather, water only after two to four weeks without rain.
Young plants do well with one deep soak a month in spring and summer, skipped after a good rain. Once rooted in, it needs little or no extra water outside long dry spells. Skip winter water, since wet, cold soil rots the roots.
Plant it with the same side facing the sun as in the nursery. Give a new column light shade cloth its first summer, then remove it.
Below about 25°F, frost can damage the column tips. Cover the tips with foam cups, or use frost cloth that reaches the ground, not plastic. Take covers off in the morning.
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 tall does Mexican Fencepost get?
Usually 10 to 15 feet tall in a yard. Older plants can reach about 20 feet over time.
How fast does it grow?
It grows fast for a cactus. About a foot a year is common, or roughly 10 feet in 10 years. Water in the hot months speeds it up.
Does it grow arms, and how wide does it get?
It does not grow arms. New columns come up from the base, so the clump slowly widens. Clumps usually run 3 to 5 feet wide, and older clumps can spread 6 to 10 feet.
Can I grow a living fence with it?
Yes, that is how it got its name. In Mexico, rows are planted close together, often from cuttings, along roads and property lines. The straight columns fill in as a tall green barrier. Each clump widens to about 3 to 5 feet, so plan the row with that width in mind.
How do I plant a cutting?
Let the cut end dry in a shady spot for one to two weeks so it can callus. Cuttings take root readily, which is how fence rows are started.
How often should I water it?
Wait at least one to two weeks after planting before the first water. Young plants do well with about one deep soak a month in spring and summer, skipped after a good rain. Once rooted in, it needs little or no extra water outside long dry spells. Skip winter water, since cold, wet soil can rot the roots.
What soil does it need?
Any soil that drains well. Native desert soil works, with no amendments. Soggy soil is the thing to avoid, since root rot is its main problem.
Is it cold hardy, and how do I protect it from frost?
Column tips can get frost damage below about 25°F, and plants survive down to about 20°F. When a hard freeze is forecast, cover the tips with foam cups.
Can it take full sun and a hot west wall?
Yes. It grows in full sun and handles reflected heat off walls, and it also grows in part shade. On the hottest west and southwest sides it can show some sunburn, which is more cosmetic than harmful. Newly planted columns do better with temporary shade their first summer.
Does it have spines? Is it a problem for pets?
Yes. Short spines run in neat rows along the ribs. They are smaller than on many cactus, but they are still sharp and can hurt a pet that chews or brushes against it.
Does it flower?
Yes. Small pink, tube-shaped flowers open along the ribs in spring. Spiny red fruit can follow, and the fruit is edible and used for jams and jellies.
Do deer or rabbits eat it?
It is rated deer and rabbit resistant.
Mexican Fencepost, Totem Pole or Cardon?
Mexican Fencepost grows fast, with straight ribbed columns lined with small spines. Totem Pole grows slowly and has few or no spines. Cardon looks like a saguaro and grows much taller and more massive.
Mexican Fencepost for sale in Arizona, delivered to you
Mexican Fencepost is the straight, ribbed column cactus behind the living fences of central Mexico. It grows fast for a cactus, takes full sun and reflected heat, and gets by on low water. Below is what to expect in a Valley yard, from height and growth to water, cold and planting cuttings.
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Mexican Fencepost, the living fence cactus
The name comes from its use in many villages and towns in Mexico, where rows of it are planted as living fences, mainly along roads. It is native to central Mexico, in Hidalgo, Querétaro and Guanajuato. It is also sold as Pachycereus marginatus.
How tall does Mexican Fencepost get in Arizona?
Plan on 10 to 15 feet tall, with older plants reaching about 20 feet. It grows straight up and adds new columns from the base instead of arms. Clumps usually run 3 to 5 feet wide and can spread to 6 to 10 feet with age.
How fast does Mexican Fencepost grow?
It is fast for a cactus, about a foot a year, or roughly 10 feet in 10 years. Some water in the hot months makes it grow faster.
How do you start a Mexican Fencepost fence from cuttings?
Let each cutting dry in the shade for one to two weeks so the cut end calluses. Plant in soil that drains well. In Mexico, cuttings are planted right where the fence should go, and they take root and fill in.
How often do you water Mexican Fencepost?
Water young plants about once a month through spring and summer, skipping it after a good rain. Once rooted in, it gets by on little or no extra water except in long dry spells. Let the soil dry out between waterings, and skip winter water.
Is Mexican Fencepost cold hardy in Phoenix?
Column tips can get frost damage below about 25°F, and the plant survives to about 20°F. On hard freeze nights, cover the tips with foam cups.
Mexican Fencepost vs Totem Pole cactus
Mexican Fencepost grows fast, with ribbed columns lined in small spines. Totem Pole grows slowly and has few or no spines.
Mexican Fencepost flowers and fruit
Small pink, tube-shaped flowers open along the ribs in spring. Spiny red fruit follow, and the fruit is edible and used for jams and jellies.
We deliver across the Valley, from Phoenix, Scottsdale and Mesa out to San Tan Valley, Maricopa and Casa Grande, and up to Prescott, Sedona, Payson and Globe. See delivery areas and rates.