Pachycereus marginatus

Accession Count: 33
Common Name: Mexican fence post
    • Select which
      accessions to find:

Family Name: Cactaceae
Botanical Name: Pachycereus marginatus
Sub Species:

The Mexican fence post is a dark-green columnar cactus that develops basal branches when mature, possessing 5-7 ribs. Stems are rough and erect, growing up to 4 m in cultivation, and 15 m in the wild. Cacti are spined along each rib, with mature cacti possessing shorter spines than juvenile specimens. During the spring, pink to green flowers will develop from areoles, leading to spiny red fruits.

The areoles of P. marginatus create a confluent line among each rib, to an interesting visual effect, especially when blooming. As the spines and flowers only emerge along each rib, the cacti develops a “neat” appearance that is popular in cultivation (1).

Compound: Pac mar
Geographic Origin: Mexico
Ecozone Origin: Nearctic
Biome Origin:
Natural History: Pachycereus marginatus grows wild in Mexico and other border states that have the dry desert climate. (2, 3, 4) The plant hails from southern Mexico and has migrated north the cactus is know for its rapid growth (3). P. marginatus is known to be from southern Mexico but no information states where it exactly came from in Mexico. The reason for this is it is believed that the plant was cultivated and moved around so much in Mexico it became “naturalized” in Mexico (2).  The tree is very common and is able to grow anywhere it can get enough sun and heat (5). The most common place to find this plant is in Mexico and in the border states that alight Mexico, Texas, New Mexico, Arizona, and Southern California (5) Its is noted that the popularity of this cactus has cause it to be cultivated and sold for homes that like to have potted plants (5). 
Cultivation Notes: Pachycereus marginatus is a long green cactus that is known for it flowers it blooms in the spring that can come in a variety of colors (2, 3, 4, 5). Being like most cactus water is not a big factor for this plant survival (2, 3, 4) Mexican Fence Post are known for their durability in the heat and can last in colder climates that reach 20  after that the plant risks going into shock or freezing (3, 5) The way the tree seeds itself is by droppings, the fruits ripen and fall to the floor starting a cycle for new plants to grow (5). If seeds are properly cleaned and stored they can be used later to plant (5). This Cactus can be bought at local stores around the south west and it is advised you plant them during the spring and summer seasons (5).  
Ethnobotany: Pachycereus marginatus is an important part of our ecosystem (2). Being a cactus, it stores large amounts water, meaning in times of need, desert dwelling animals and humans have harvested the water for survival (4). The fruit that accompanies the flowers can be used to make jams and jellies as well (4). The cactus is most commonly used today for landscaping, it fits the southwestern theme very well (5). It is also favored for its low maintenance and little amount of watering. The Mexican fence post has landscape value as an accent, specimen, or character plant in arid, tropical landscapes.

Height: 11 - 15 feet
Width: 6 - 10 feet
Growth Rate: Fast Growing
Grow Season: Summer
Flower Season: Spring
Color: Yellow
Function: Accent
Spread: Spreading
Allergen: Non-allergenic
Invasive: Benign
Toxicity: Benign
Hardy: Hardy
Water Use: Low water Use

  1. Llifle Encyclopedia of Cacti, retrieved from
  2. The Red List
  3. Arizona Municipal Water Users Association
  4. Xeriscaping tips for desert gardeners
  5. Dave's Garden
  6. Jones, Warren D, and Charles M Sacamano. Landscape Plants for Dry Regions: More Than 600 Species from around the World. Fisher Books, 2000.

Pachycereus marginatus