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Much of the following is reprinted with permission from "Cacti & Succulents," a fact sheet available through the William T. Kemper Center for Home Gardening at the Missouri Botanical Garden. With the huge variety of succulent species, forms and habitats in the world, please be aware that not all points expressed here apply to every plant. For more information and growing tips for various cactus and succulent species, visit the Plant of the Month pages.
Kemper Center for Home Gardening
At Missouri Botanical Garden
4344 Shaw Blvd.
St. Louis, MO 63110 USA
Open daily 9 a.m. to 5 p.m.
Cacti and Succulents as House Plants
A group of plants called succulents that have fleshy stems, leaves and/or roots are often chosen as house plants for direct light conditions. Their ability to endure drought is reflected in their succulent leaves, stems or caudices, where water is stored.
These plants come from many plant families, most notably the cactus family. Others in this group, however, come from subtropical areas where light conditions are less extreme and moisture is more abundant. In this second group we find the Christmas, Thanksgiving, Easter and orchid cacti. Some refer to this group as the jungle cacti, because they are found as understory plants in tropical forests.
Succulents make good house plants because they are generally accommodating and resilient, and can grow under average home conditions of higher temperatures and low humidity. If you have a southern window that receives direct light and becomes fairly warm, you might consider a succulent for that spot. However, a little research about the plant's natural habitat will help determine specific watering needs and other aspects of care.
How Much Light
Cacti and succulents generally require at least four hours of bright, direct light each day. However some, including the jungle cacti, prefer medium light intensities and should never be placed in direct light except during the winter. Overall, if you wish to move a plant grown in indirect light into brighter light, this should be done gradually.
All succulent plants love to be outside for the warmth and fresh air of the summer growing season. Be careful when moving them out, however. Plants will be damaged if placed directly into full sun. Instead, move plants to a position with filtered light, such as under a tree or shade screen, to prevent sunscald. This appears as a bleaching of the foliage that results in a yellow-white color. In addition, plants in direct light benefit from periodic turning, so that all sides are exposed. This is especially true for plants with heavy growth.
Temperature and Humidity
The temperatures in most homes are generally adequate to maintain cacti and succulents year-round. Most cacti and succulents also tolerate the low humidities of homes. Many grow better and flower more in spring if presented with cool conditions during the winter, which reflects their natural rest period. Window sills and cool basements are good sites for these plants. The light should be as bright as possible.
Many tropical succulents from East Africa and Madagascar need warm winter quarters. Such warmer locations call for more frequent watering, especially when indoor heating makes humidity more difficult to regulate. Jungle cacti such as Christmas and Thanksgiving cacti also require higher humidities and should be placed on a tray of moistened rocks to promote flowering and flower retention.
Watering Cacti and Succulents
Succulent plants come from six continents and are included in over 70 plant families. While there is no single recipe for their proper watering, some general rules apply.
Overall, cacti and succulents should be watered more frequently during the period of greatest growth. For most plants, this occurs between the months of March and October in the Midwest. Plants in full sun and/or clay pots naturally dry out more quickly than those in filtered light and/or plastic pots. Be aware that underwatering in summer is a major killer of prized plants.
Moisture conditions should be checked every two to three weeks. This is simply done by sticking an index finger into the soil. Water larger pots when the top inch of soil feels dry. Smaller pots require more frequent watering. Water thoroughly early or late in the day, so water drains from pots. Do not let your plants' roots completely dry out. This can cause root loss and put plant health at risk.
Winter is a period of dormancy or very slow growth for most cacti and succulents. For plants kept at household room temperatures, water every one to two weeks. Water only once a month if plants overwinter in cooler conditions. Overwatering at this time can result in root rot by fungi organisms.
Jungle cacti should be kept evenly moist year-round, especially during the flowering period of late fall or early spring. When flowering has stopped, water should be withheld to allow the top of the soil to dry out before rewatering.
Cactus Soil Mixes and Recipes
Soil mixes both support plants and serve as media from which the plants absorb water and nutrients. They must be porous enough to allow both air and water to move freely around the roots.
Soil mix should match the moisture requirements of individual plants. This is better than trying to match the frequency of watering to the soil mix. All cacti and succulents require good drainage, so soil mixes should be coarse. Good-quality soil mix combined with drainage material like small gravel, turface or traction sand in a 3:1 ratio works well for most succulent plants. Do not use sand in soil because it can suffocate roots by clogging soil pores and holding too much water.
For tropical cacti like Christmas and Easter cacti, mix one part aggregate with one part soil mix and one part peat. The peat will hold more moisture, as required for these plants.
Fertilizers and Fertilizing
Generally, succulents and cacti do not demand a great deal of fertilizer to grow. Amounts recommended for typical house plants should be cut back to one-quarter to one-half the concentrations typically recommended on labels.
Fertilizer can be used several times a year during the active growth phase, which begins in March and ends in October. Apply fertilizers only when soil is moist to avoid burning plant roots. In winter, no fertilizer is necessary, as this represents a dormant period for most plants.
Repotting and Propagation of Cacti and Succulents
Most cacti and succulents prefer to be somewhat pot-bound. This condition leads to more frequent flowering in the case of jungle cacti. If plants become too pot-bound and the top growth is unbalanced, they should be repotted. The new pot should only be about one inch larger in diameter than the previous one. Tall plants should be repotted in a container which is at least one-half the size in diameter as the plant is tall.
The time to repot is when growth begins in the spring. Potting during the dormant stage will set a plant back because a part of the root system may be lost during the process and it will be very slow to recover.
Cacti and succulents are among the easiest plants to propagate because they have such a large storage sytem of water and nutrients, and are thus very well adapted to adverse growing conditions. Some cacti actually lose parts of their stems as an active way to self-propagate. These parts may lay dormant for over a year and become quite desiccated before new roots emerge as a response to wetter conditions.
There are three forms of vegetative propagation where some part of the mother plant is removed and used to grow the new plant. These are by offset division, stem cuttings and leaf cuttings.
Although more time-consuming, some cacti and succulents can also be started from seed. It can take two to five years to establish new seedlings with the slow growth rates characteristic of these plants. Collectors and hobbyists who start plants from seed are usually motivated by the experience, which is awesome and humbling. The resulting plants are the trophies.
The most popular way to propagate cacti and succulents is by division. Certain cacti produce offsets that can simply be pinched off and potted after a couple days of drying at room temperature to callus over the wound. The soil should be kept damp for about four weeks. Check for roots by tugging at the plant. If the pot lifts with the plant, you can be assured the plant has rooted.
The other ways many cacti and succulents can be propagated are by taking cuttings of stems and leaves. Plants can be cut just above a node with a sharp, clean knife. The excised part should be air dried for two days, then potted by burying a portion of the plant part in soil mix.
In a similar way, leaf portions from some plants like Sansevieria can be cut and potted. Leaf segments for this plant should be about 2 inches long. A segment should be potted in such a way that the basal portion that was closest to the root system of the mother plant is buried in the soil mix. Roots will not form from segments that are upside down.
Cactus and Succulents That Flower
Although it may take a number of years, most small cacti and succulents will eventually flower. Some produce a tremendous number of blossoms over a short period, and some produce only one or two. Additionally, some plants only produce flowers at night, and the blooms last a single 24-hour period. Others bloom in full sun.
The most prized flowering plants in this class are the jungle cacti. These plants are native to shaded tropical forest floors and therefore do not fair well under intense light. Flowers are initiated when the day length becomes short, as would occur in early winter and spring.
The famous Thanksgiving and Christmas cacti are two such plants that respond to short days. These plants should be placed in a window that receives indirect light. They do best when they become pot-bound and the soil moisture is evenly maintained. Changing conditions in the middle of the flower response will surely result in bud drop, a condition that plagues many indoor gardeners.
[ Common Cacti and Succulents ]
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