CACTI are amongst the most fascinating plants a gardener can grow. Indeed, if your indoor gardening is confined to the centrally-heated living room, it is one of the most successful groups of plants to cultivate as all, except the jungle cacti, thoroughly enjoy centrally- heated conditions.

An interest in cacti is often initiated in children who find them not only curious, but easy to grow. Indeed, as a novice plant they are perfect, for apart from gross over-watering or frosting, the majority of popular kinds are difficult to kill. They need not take up too much room either, a modest window ledge being capable of accommodating a reasonably comprehensive collection of shapes and sizes. As many cacti will flower when quite small, there is no reason why, with the careful selection of varieties, even a small indoor collection should not boast some blossoms for much of the year.

There is a much quoted saying that cacti will only flower every seven years. This is not true, for many will produce a good show every season.

Amongst the most reliable are the small round barrel cacti called rebutias. These flower very regularly with blossoms that are often of a vivid red hue. Mammillarias are also barrel types but variable in their flowering frequency, although the popular florists' kinds do bloom when very tiny.

Cereus cacti are more architectural plants than anything else. It is these tall cylindrical cacti which comprise much of the desert flora of cowboy films. Although growing quickly, they are not free flowering.

The most reliable kinds from the flowering point of view are the jungle cacti or epiphyllums. It is this group which also loosely embraces the Christmas and Easter cacti. Unlike the very prickly kinds, these are plants from the jungle rather than the desert and demand much damper and partially shaded conditions.

While traditional spiny cacti must be grown in a very open, free-draining soil-based compost, the jungle kinds demand a fibrous organic mixture. The perfect kind of compost for them contains up to half of well chopped green sphagnum moss, while the remainder is a standard soil based mixture such as John Innes No 3.

All cacti need proper care and attention, even if they are tolerant of neglect. Apart from regular watering and feeding during the active growing season they must be protected from pests and diseases. The three-weekly spray with a combined systemic fungicide and insecticide should keep most problems at bay.

Repotting is necessary during most seasons, even if the plants are only replaced into the same sized pots, for it is important to retain a free-draining compost structure. As cacti often look quite fit and well, even after the compost has begun to deteriorate, they are regularly left untouched, not least of all because of their prickly nature.

Apart from being fun to look after, cacti are interesting to raise from seed. Most garden centres offer mixed packets of seed which contain a selection of easily raised kinds in most of the popular shapes. Several of the barrel cacti will flower in eighteen months after sowing.

Philip Swindells

WHAT'S NEW

Pearls is a raspberry-pink flowered rose with white flecks in the petals. It is suitable for ground cover.

Elan is a perpetual fruiting variety of strawberry which is ideal for strawberry pot or container culture.

Traditional Italian herb and vegetable seeds are available now under the Franchi Sementi label.

Q My snowdrops have finished flowering. Is it safe to move them now?

A Yes, snowdrops move easily when in leaf, ideally just after flowering is over. Transplant immediately. Do not allow the bulbs to dry out.

Q I have some white cotton wool-like growth on my parlour palm. Is this harmful?

A This is mealy bug. A creature which is feeding on the palm. Spray with a systemic insecticide and wipe off the worst colonies with a paper kitchen towel.

QAt what time of year should I clean my pond out?

A April is a good time, but do not clean out the pond unless it is really necessary because of congested plants and dirty water. Most ponds only require a full clean out every four or five years.