Growing Cacti

Cacti are very common houseplants, and although awkward to hold they bloom bright big flowers in the summer. How can you keep them healthy?

Cacti (also known as Cactaceae) were first discovered in the harsh, tropical American desert, where they can happily survive with little water due to the ingenious water-saving traits; their leaves are reduced to spines and they have a thick layer to protect them from the suns harmful rays. Some even posses water-storing stems.

A very adaptable plant, they are likely to survive good sunny conditions, aside from severe frost. Having been taken from the arid surroundings of the desert and cultivated in more tolerable conditions, they are often used as small ornaments, houseplants and sometimes for their soft timber.

Although being somewhat difficult to handle due to their spiky spines, many species have fruits that are edible. The Prickly Pear is a prime example. This cactus (true name Opuntia) is native to the North and South of America and is cultivated for its food. Although obviously useful, it has become known as a troublesome weed in countries such as Australia and South Africa. Their spiny stems, a common trait of cacti are used to produce oil, and the stems used as animal feed.

A common gift or houseplant, cacti can be inexpensive to buy - should you choose the small variety. These petite specimens are incredibly slow growing and therefore make excellent indoor plants. Picking a well rooted, mature plant can be priced at around £45/$60.

Growing cacti

If you are considering growing cacti follow these tips to ensure they survive more than one season:

1. Desert plants need as much sunlight as they can get, but keep them out of direct sunlight.

2. If growing on a windowsill, you must let them stand outside during May to September - they need a cool, dry spot for the winter.

3. A winter temperature of 5°C is adequate.

4. A good compost is needed: 1 part grit and 3 parts specialised cacti compost (available at most good garden stores)

5. When grown in this compost they should be watered well during April to September.

6. Do not allow them to dry out.

7. After September reduce watering and leave them dry during December to January. As sunlight improves, gradually begin watering again.

8. Cacti are prone to pests. The mealy bug, a small white creature that leaves a woolly deposit on the stem is a common attacker. To deter these pests, use a nicotine spray and regularly re-pot.

9. Rotting can be a big problem, due to too much water in the resting period (the winter) or too cool a temperature in the winter. If you find rot and it isn't too extensive cut off the top and treat it as a cutting. Dust the cut areas with sulphur to prevent further infection.

Making cuttings

Cacti are easily propagated from good cuttings, and these should be taken in spring and summer. Where stems are cut, dry it out for a few days before planting in the specific compost. Otherwise the cutting may rot.

Growing from seed

Purchasing cacti seeds may be difficult. You will need to go to a large seedsman, as you may not find them readily available at your local garden store. Wide selections are available, ask for a little advice when purchasing. When growing from seed they need good light, but keep them shaded from direct sunlight. If you are able to heat the seeds when germination starts you may sow early in the year, if not, wait until late Spring when the weather heats up a little and you are not tolerant of frosts.

Which variety do I buy?

There are over 2000 species of cacti known, varying in size and shape - some reaching a height of 10 meters or more. Taking a trip to your garden centre, you'll see the many varieties available. Listed below are a few of the more common varieties, and ones you are likely to find.

Astrophytum myriostigma

Found in: Mexico

Height: grows to 6 inches

Appearance: Covered in slivery scales, yellow flowers in summer and autumn.

Special instructions: Require extra-porous compost and careful watering.

Chamaecereus silverstrii

Found in: Argentina

Height: Many stems, each about 2-3 inches.

Appearance: Many stems, red flowers produced in summer.

Special instructions: A cold, dry winter improves flowering the following year.

Echeveria derenbergii

Found in: Mexico

Height: small plant, 3-4 inches.

Appearance: Green leaves covered in waxy coating with a red point.

Special Instructions: Should be be-headed in spring and the top re-rooted.

Echinocactus grusonii

Found in: Mexico

Height: after several years 6 inches - very slow growing.

Appearance: Dense pale spines.

Special Instructions: Best grown from seed.

Echinocereus knippelianus

Found in: Central Mexico

Height: diameter of 2 inches.

Appearance: Five-ribbed cactus with small spines. Pale pink flowers.

Special instructions: Water carefully, best grown from seed.

Eriocactus leninghausii

Found in: Brazil

Height: a slow grower - 3 inches.

Appearance: cylindrical covered in long bristles. Yellow flowers in spring.

Special instructions: best for indoor ornaments.

Opuntia microdasys rufida

Found in: Mexico

Height: up to 12 inches high

Appearance: bright green dotted pads.

Special instructions: Handle with care, the spots may irritate the skin. Disfiguring spots may occur during the winter - move to a slightly warmer spot.

Trichocereus spanchianus

Found in: Argentina

Height: up to 4 ft, 12 inches more common.

Appearance: tall, cyrindrical. Yellow-brown spines.

Special instructions: One of the most attractive and easily grown.

Pachyphytumn oviferum

Found in: Mexico

Height: 3-4 inches

Appearance: oval shaped leaves, sometimes pink.

Special instructions: Do not splash the leaves with water, or touch them - they easily mark.

Rebtia minuscula

Found in: Argentina

Height: 4 inches.

Appearance: rounded, dome shaped, covered in yellow spines.

Special instructions: flowers in spring and are self-fertile.

The main ingredient in a cactus's survival is sunlight. Couple this with the correct positioning for the time of year (see above) and your cactus will be well on the way to surviving a lifetime.

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