Cacti and Succulents: Growing Conditions and Varieties
The cultivation of cacti is a fascinating hobby and most kinds will succeed in a greenhouse with a minimum winter temperature of 7°C. (45°F.). During the spring and summer temperatures can rise to 18 to 21°C. (65 to 70°F.) with sun heat, provided ample ventilation is given. Cacti are sun-lovers and need to be stood in the lightest part of the greenhouse. In summer they can be stood in a sunny cold frame, preferably with the pots sunk in a bed of ashes.
The time to pot cacti is in the spring just as new growth is beginning. John Innes No. 1 Potting Compost can be used with the addition of two extra parts of coarse sand and two parts crushed brick. Cacti must never be placed in pots which are too big: generally, one size larger than the ones they have been occupying is sufficient.
Handling the plants can be difficult because of the spines and it is wise to make a paper collar which is placed around the plant to serve as a handle. Remove some of the oldcarefully and place the plant in its new pot, firming fresh compost around the roots.
Growth is made in the spring and summer and during this period plenty of water is needed, but in winter when the plants are resting the soil must be kept dry and watering should only be necessary if the plants begin to shrivel.
Below is a small list of cacti and succulents:
The lobivias are attractive small cacti which flower while still young. One I have a regard for is Lobivia famatimensis, a yellow-flowered species which has numerous varieties withof other colours, including red, pink and white. This cactus likes a sunny position.
Euphorbia is a huge family including plants of many different kinds but the one I would mention now is Euphorbia splendens. The Crown of Thorns, a species which bears scarlet bracts and sharp thorns. This will make a succulent. Shrubby plant up to 3 ft. tall. It likes a sunny position.
The lithops are the Living Stone or Pebble Plants, all natives of South-west Africa and intriguing in their mimicry of stones or pebbles as the common names suggest. Lithops olivacea, with yellow flowers, is a species often grown. Drainage must be specially good for these plants. They need a fair amount of water between May and November but no water at all from then until April.
Some of the columnar ‘woolly’ cacti are of especial interest, like the striking Cephalocereus senilis or Old Man Cactus, which comes from Mexico. The long white hairs give it a distinctive appearance. This plant needs full sun and very careful, restrained watering. Extra lime added to the compost is beneficial.
The conophytum are related to the lithops and, like them, come from South-west Africa. These need plenty of sunshine and good, a fair amount of water during August and September when they are growing and very little from then until July. Species grown include Conophytum bilobum and C. nohile.
A sedum with attractive glaucous foliage and white flowers which is worth adding to a collection is Sedum helium. A sunny position is needed.
The easily cultivated, winter-flowering Echeveria retusa is excellent for a cool greenhouse, mature plants being grown in 5- or 6-in. pots in John Innes No. 2 Potting Compost. The stems should be neatly staked as they develop to support the clusters of coral-red flowers.
The species grown in greenhouse and home is Kalanchoe blossfeldiana in one or other of its various forms. These attractive succulent plants have glossy, fleshy leaves and red, pink or yellow flowers. They make rounded domes some 9 in. tall.
Another cactus with an appropriate common name is Aporocacius flagelliformis, the Rat’s Tail Cactus. It has long, trailing. Ribbed stems, covered in small spines, and bears pink or red flowers freely.