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Mexican Fence Post

Pachycereus marginatus

Mexican Fence Post Cactus
Cactus & Succulents

A tall, clean column of dark green, ribbed stems, each rib lined with neat white spine clusters. It branches mostly from the base and has a sleek, architectural look that suits modern desert landscapes.

Large
Full sunpreferred
Ask a designer about it
Mature size10–20′ tall over many years; clumps to about 6′ wide
Growth rateSlow to moderate
Water useVery low
SunFull or reflected sun
BloomSmall pinkish to white flowers along the stems in spring
Cold hardinessTips can be damaged in the mid-20s°F
FoliageDark green ribbed columns lined with white spine clusters
SpinesShort, whitish and closely set along each rib

Living with it in the Phoenix Valley

Watering

Follow the cactus guidance in our Landscape Care guide. It needs little to no extra water once established. Good drainage matters most, especially in irrigated beds, since soggy soil leads to root rot.

Pruning

None needed. Remove a damaged or leaning column at its base if needed.

Cold

It is one of the more frost-tender columnar cacti. Most Phoenix winters are fine, but in a hard freeze cover the growing tips, especially on young plants and in low spots where cold air settles.

How our designers use it

Vertical accent

A cluster of columns adds height and structure against a plain wall or at a corner of the house without casting much shade.

Living screen

Planted in a row, the columns form a narrow, upright screen, the way it is used as a fence in Mexico.

Large containers

It holds up well in big pots on patios and courtyards.

Good to know

Around the pool

The spines are short but sharp. We generally keep it a few feet back from the pool edge, walks and play areas, where it works well as a backdrop rather than an edge plant.

Frost

Freeze damage shows as scarred, discolored tips. Covering the tops on the coldest nights is easy insurance.

Pairs well with

Similar plants

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Picturing one in your yard?

Our designers can show you where it will thrive, what to plant beneath it and how it fits the rest of your landscape.

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