Cacti should not be watered during their period of dormancy, which usually occurs during the winter months. During winter cacti should be left without water, especially if kept in an environment with a fairly low temperature. Cacti must be watered during their active periods.
It is difficult to provide precise rules pertaining to the watering of cacti and succulents. For example, if you were cultivating a type of desert cactus, in the month of January, this plant would need to be watered once or at the most, twice and its stem should be sprayed with water three or four times. In February it should be watered 2-3 times a month. March and April – four times – a little supplement of misting with water should also be performed. In May, 4-5 waterings are sufficient, if the weather is not unusually hot. Do not water your desert cactus during June until near the end of July. Near the end of July till September the cactus may be watered 2-3 times a week. When the weather becomes cool, the program should be reversed; so by December plant should be supplemented with a minute amount of water.
According to how much should be given, the amount should be sufficient to soak all soil in the pot – or surrounding the roots – and excess water should be drained freely. During summer, occasional rain showers will do no harm. During a protracted period of rain, however, cacti should be placed in a sheltered area. The best time to water cacti is early in the morning after sunset or at least after the surrounding environment (or pot) has cooled down.
Technically, water should be free of chlorine and alkaline salts, but ordinary tap water seems to suit cacti well in the United States. Although in Britain, water is rich in chlorine and alkaline salts, therefore rainwater should be used instead of ordinary tap water. When spraying plants with water, whitish marks may be left on the stem, thus blocking stomata. This is probably because undistilled water was applied to the cacti. To obtain distilled water, use tap water that has been boiled for 30 minutes.
Cacti and Succulents need regular feeding during their growing season (Spring-Summer). They need a balanced range of minerals. Potassium (K) to encourage flowers and fruit, Phosphorus (P) for good root growth, and Nitrogen (N) for vigorous top-growth. Cacti also need other trace elements.
Cacti and Succulents require feeding in two different stages. Add powder or granular fertilizers to potting mix during planting time. Thereafter apply liquid, or solid fertilizers throughout the growing season. Fertilize cacti half as often as the plant is watered. Cacti and succulents respond well to liquid fertilizers consisting of 15% nitrogen, 15% potassium, 30% phosphorus, and all of the other trace elements.
Mature cacti and succulents grow well in a warm climate at a minimum temperature of 61F (16C). Cacti usually need direct or filtered sunlight to perform photosynthesis. Natural light can be supplemented by artificial light such as fluorescent lighting.
Cacti have adapted to survive in solid clay and pure sand, with limited nutrients. But to grow healthier cacti, they should be grown in soil or potting mixture which provides free-draining and retains moisture. Always use a gritty mixture to harbor pests and diseases, and to ensure correct drainage. Most cacti prefer slightly acidic soil. To make the soil more acidic, add plenty of peat.
Pots and Containers:
Mostly shallow-rooted succulents and cacti do not require a great depth of soil. Plants less than 6 in. (15cm) across are best grown in pots that are about 1 in. (2.5 cm) wider than the plant; larger plants require a pot 2-4 in. (5-10cm) wider than their diameter. For pots up to 3.5 in. (9 cm) across or for very tall plants, full-depth pots are best. Otherwise, use half pots, known as pans, which are 3-6 in. (8-15 cm) deep.
Make sure that all outdoor containers have drainage holes and line the bottoms with material such as turface or gravel.
When growing plants together in one container, select plants with similar cultural needs and growing seasons. Many slow-growing succulents do well when planted with desert cacti, but can be swamped by fast-growing succulents.
Buying and Selecting Cacti and Succulents:
Supermarkets, garden centers, and florists generally stock cacti and succulents that are easy to grow. They do, however, offer only a limited choice. A specialist cactus nursery or a local cactus show will have a much larger and more interesting variety of plants on sale. Some cactus nurseries and botanic gardens have permanent collections. It is well worth visiting one or two of these in order to see what mature specimens of cacti and succulents look like and how to display them effectively. Choose unblemished plants that display signs of new growth. A well-presented plant in a fresh, weed-free potting mix shows that the grower has looked after it well. Do not buy cacti or succulents that look as if to be unhealthy or in poor condition. Symptoms of poor growth are often more visible in succulents than in cacti. Avoid plants that show signs of disease or pests, that have few or pale leaves, and spindly growth, or that are potbound or in poor potting mix. Cacti that are in poor condition show signs of pests, diseases, or uneven growth. Check that the skin is not dull and the spines are not damaged. Cacti that may appear to be lopsided are because of a poor root system.