Family: Cactaceae
Habitat: Argentina, Paraguay, Brazil, Bolivia, Uruguay, but also the Greater Antilles and the Bahamas and the state of Florida in U.S.A.
Cultivation: Easy. A bright spot, warm temperatures and scarce waterings will do well.
Curiosity: Harrisa owes its name to William Harris, a Jamaican Botanist.


Harrisia is a genus of night blooming cacti including about 20 species.

They are native to South America: in particular, Argentina, Paraguay, Brazil, Bolivia, Uruguay, but also the Greater Antilles and the Bahamas and the state of Florida in U.S.A.

Harrisa owes its name to William Harris, a Jamaican Botanist. According to some botanical classification systems, the genera Eriocereus and Roseocereus are considered synonyms of the genus Harrisia. On the other hand, on the market can be still found plants labelled Eriocereus and Roseocereus, along with the Harrisias.

Harrisias are perennial plants with spiny, pointed stems. These plants end up to form succulent, spiny mats, which don’t exceed an height of half a meter, however they easily spread all around due to the large quantity of seed they produce, dispersed by birds and other animals, and to their long, trailing branches that take root whenever they touch the ground.

For this reason, in the U.S.A, Harrisia has become an invasive plant: its spiny mats represent a huge problem for pasture, limiting its movement and competing with edible weeds.

The stems are rather branched, slightly slender and tend to lie down and put root when they touch the ground. They are equipped with pointed, prominent tubercles on which the areoles are located. The areoles are white and form long, thick spines, white in colour. Every areole produce one to three of these thorns. The tubercles are lined in regular intervals upon the six ribs in which the stem is divided into.

The gorgeous flowers are large, funnel-shaped, often pink tinged in white, and open at night. They develop on a scaled, slender, spineless tube ,13-15 centimeters long and form round, hairy, lumpy red fruits, 4-5 centimeters in diameter. These fruits are also polpous and host numerous (350 to 1100!) small black seeds. Seeds are dispersed by birds and mammals and germinate easily. The plantlets grow fast, forming a lot of tubers, which are one of the reason why it’s so difficult to control this plant: when an individual is grubbed, the tubers easily sprout and form a new one.

The roots of Harrisia can be either fibrous, up to 2 meters of length, or tuberous: in that case they reach a depth of around 55 centimeters.

In the ornamental plants world, Harrisia is mainly appreciated for its beautiful flowers that open in the evening and close at dawn: it has earned the name of “Moonlight cactus”.


Here below are the some species of Harrisia:

  • H. aboriginum
  • H. balansae,
  • H. bonplandii
  • H. brasiliensis
  • H. divaricata
  • H. donae-antoniae
  • H. fragrans
  • H. gracilis
  • H. jusbertii
  • H. martinii
  • H. pomanensis
  • H. portoricensis
  • H. simpsonii
  • H. tetracantha
  • H. tortuosa

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Harrisias are easy to grow and will reward you with their gorgeous flowers. Here are our cultivation tips:

  • Put your Harrisia in a sunny spot, however avoiding direct sunlight during the hottest hours of the day;
  • The minimum tolerated temperature is -4ÂșC, as long as the soil is maintained dry, nevertheless it’s better to shelter them in Winter.
  • The ideal substrate is a rich, porous, well-draining sandy soil: a standard cacti will also do well
  • Water regularly in Summer and less frequent in Autumn, then suspend completely the irrigation in Winter. Always remember to let the soil dry up completely before each watering.
  • This plant doesn’t need to be fertilized so frequently. Once a year during its growing season will be sufficient.
  • Repot in Spring every year, as this plants grow fast.

To propagate Harrisias, seeds or cuttings are the best methods. Also, usually the stems lie down and put roots when they touch the ground: if you notice that this is happening, it will be sufficient to cut the stem and separate the two individuals. Cuttings can be taken from shoots in Spring and Summer, should be then left to dry up in a warm place for a week, and then put into a sandy substrate. They usually root in 2-6 weeks.

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