Cactus Care: Growing Methods and Daily Maintenance Tips

Cactus is a common type of houseplant. With proper care, it not only grows quickly but also develops a glossy, vibrant body and blooms abundantly. Cactus prefers warmth and fears severe cold; if the room temperature drops below 2°C, it will be damaged by frost and die, so it should be moved indoors in winter. How much to water depends mainly on temperature, light duration, wind and many other factors. If the temperature is low, the cactus grows slowly and uses less water, so watering should be controlled; the lower the temperature, the drier the potting soil should be kept. Mature cactus bodies are more drought-tolerant than small ones.

Temperature

Cactus prefers high temperatures and a dry environment. In winter, the room temperature should stay above 20°C during the day and not fall below 10°C at night. Too low a temperature easily causes root rot.

Light

Cactus requires plenty of sunlight, but in summer it should not be exposed to strong direct sun and needs appropriate shading. For indoor cultivation, artificial light can be used to promote healthy growth.

Potting Soil

For potted cactus, the soil should be sandy soil (or sandy loam) with good drainage and aeration that contains lime. It can be mixed from 2 parts loam and 2 parts leaf mold, 3 parts coarse sand, plus 1 part limestone gravel or old lime wall debris discarded when old buildings are demolished. It can also be mixed from 2 parts loam and 2 parts coarse sand, with 1 part each of crushed brick, leaf mold and old lime wall debris. When planting, a small amount of crushed brick and tile pieces should be placed at the bottom of the pot to ensure smooth drainage.

Planting

Planting into pots is best done in early spring. The pot should not be too large; it is best if it can hold the cactus body with a little space to spare. If the pot is too large, the water cannot be absorbed after thorough watering, air cannot circulate in the pot, and the roots easily rot. A few taproot types, as well as Lophophora williamsii and giant barrel cacti, require deeper cylindrical pots. Shallow-rooted types such as Mammillaria and Rebutia can use shallower ordinary pots.

Repotting

For potted cacti and succulents, it is best to use highly breathable clay pots, with crushed brick particles placed at the bottom as a drainage layer. Cacti have relatively small root clusters, so the pot should not be too large; the pot diameter should be close to the diameter of the plant body for a neat and harmonious look. When repotting, part of the old roots should be cut off, and after drying for 4—5 days, they can be planted into pots. Planting should not be too deep; it is best if the root crown of the body is level with the soil surface. To avoid root rot, newly planted cactus should not be watered; simply spray 2—3 times a day, and after half a month a small amount of water can be given. Only after one month, when new roots have grown, can watering be gradually increased.

Watering

In summer, the best time to water is early morning; in winter, it should be done before noon on clear days; in spring and autumn, morning or evening is fine. Generally, do not pour water from the top, otherwise ugly spots will appear on the body over time. Under normal circumstances, watering must be thorough, and for this reason the soil must be loosened regularly so that the potting soil can evenly absorb enough water.

Summer is the growing season for cactus. With high temperatures and high water demand, it must be watered thoroughly, preferably in the early morning or evening when temperatures are low; at noon, when it is hot, watering can easily cause sunburn on the body. During the hot and rainy plum season, watering should also be appropriately reduced. For cacti with a sunken top, be careful not to let water enter the depression, as this can cause rot; this is even more important when watering in the evening.

During winter dormancy, watering should be reduced, and it is best to keep the potting soil from becoming excessively dry; the lower the temperature, the drier the potting soil should be kept. Mature large cactus bodies are more drought-tolerant than small seedlings. In winter, watering should be done on clear mornings. As the temperature rises, the plant will gradually come out of dormancy, and only then can the frequency and amount of watering gradually increase.

Fertilizing

Potted cactus can also be fertilized appropriately during the growing season, especially those grafted onto Hylocereus undatus, for which fertilizing should be taken even more seriously. A fully decomposed dilute liquid fertilizer can be used, applied once every 10—15 days. After autumn begins, pay attention to controlling fertilizer and water; generally applying once a month is sufficient, until early October
when fertilizing should stop. If fertilizer is not controlled and the cactus is allowed to continue growing, the tender body is prone to frost damage when overwintering. When fertilizing, be careful not to get it on the body; if it does get on, rinse it off with water promptly.

Base fertilizer should be mixed into the growing medium in an appropriate amount before potting or repotting, such as fully decomposed oil cake meal, bone meal, chicken and pigeon manure, etc., and left to sit for a period so the fertilizer and soil fully blend. For top dressing, according to the plant's growth, during the vigorous growth periods in spring and autumn, apply fully decomposed feather, hoof and horn or oil cake fertilizer water once every two weeks. Note that the root osmotic pressure of cacti and succulents is very low, so the fertilizer water must be diluted and weak; heavy concentrations and raw fertilizer must be avoided. It can also be applied alternately with a mixed solution of 0.1% urea and 0.2% potassium dihydrogen phosphate, with the amount of fertilizer water used just enough to cover the surface of the potting soil. For home cultivation, if the potting soil has a high organic matter content, chemical fertilizer alone can be applied to keep the environment clean. Fertilizing is prohibited during periods of high heat and low-temperature dormancy.