There is something about the plush form of a succulent that captures the heart of many a gardener. Succulents are a broad category of plants, including cacti, that have adapted fleshy leaves or stems for water storage. The relatively large interior to exterior area ratios of these plants reduces loss of water into the atmosphere. They originate in all parts of the world where periods of drought are common.
Non-cacti succulents are well adapted to the dry, winter conditions suffered by most New York area houseplants but they are somewhat difficult to grow indoors because they need generous amounts of daily sunlight. Here are some rules of thumb for successful indoor cultivation of non-cacti succulents in our area.
Light is where many succulent gardeners fall short of the needs of their plants. It is critical that you place your succulents in a window where they will receive a minimum of six hours of sunlight per day. Without extended, direct light, your succulent will begin to stretch and lose its attractive, compact form. Echeverias are particularly prone to stretching, but there are some succulents that can get by with somewhat less sunlight. Haworthias and gasteraloes will live happily in many less than ideal windows.
If the sun in your sunniest window is not adequate, artificial lights should be considered, alone or in combination with natural light. A white fluorescent light, 6 to 12 inches above the plant will give good results. Artificial light is not equivalent to daylight in strength and must be delivered for at least 14 to 16 hours per day. (For more detailed information on choosing an artificial light, click on the Needles + Leaves link in the right column.)
Look for signs of sunburn (a red-brown tinge) on leaves in the summer that may indicate that your plant is receiving more light than it can handle in a south-facing window and move it somewhat further from the light source.
Too much water is the most frequent cause of succulent failure and watering requires care. Your watering regime should vary with the time of year. Typically, in the low-light conditions of winter (October through February), water only as often as is necessary to prevent the leaves of your succulent from puckering. Your plant is not in active growth at this time and prefers extended dry conditions.
When you water, water thoroughly, allowing the water to run from the bottom of the pot and checking back after 15 minutes to remove any water sitting in the plant's tray. As daylight hours increase, and the plant comes back into active growth, water more frequently but allow the soil to dry completely between waterings. Succulents have shallow roots and they will rot easily if overwatered. They do not need humidity to prosper and misting is not advised.
Succulents are happy with the temperature conditions achievable in New York area households. Daytime temperatures of 60 to 75° F. and night time temperatures ranging from 40 to 60° F. are well tolerated. Succulents require at least a 10-degree temperature fluctuation from day to night in order to grow successfully.
Your home is full of microclimates. Locations near windows may be sunny during the winter, but they are also cool (usually 10 degrees colder than the center of the room). In the summer, a south-facing window gets hotter during the day relative to the rest of the room and the rest of the house. Investigate your home’s microclimates in order to place your plants in the best spots. You may need to move plants to the most comfortable location for the season.
The soil and pot you choose for your succulent plays an important role in its health. Moisture trapped around the negligible root systems of these plants can lead to sudden death. The ideal soil should resemble the loose, free-draining mixture of a succulent's native habitat. Equal parts potting soil, peat and sand are generally best. Commercial cactus mixes are acceptable, if not ideal, and readily available but avoid those that have food already in the mix; the nutritional needs of your succulent vary by plant type and time of year. Your pot must have a draining hole at its bottom.
These plants are frequently sold grouped together as a miniature garden in a shallow pot but these conditions may not benefit your plants. The shallow containers are chosen for charm not drainage and frequently lack the hole at the bottom necessary for survival. Different plants need varying amounts of moisture and grow at different rates; often one plant will dominate and eventually choke out the rest. Not the pretty picture you hoped for when you purchased your miniature garden!
If you have a grouping like this, keep an eye on it and separate out any plants that are not thriving or are dominating in the group. They may need a new location as well as their own pot. If your miniature garden lacks a drainage hole, consider repotting in a container that will give these plants a better chance of survival. If transplanting, take care with the delicate roots.
Minimal nutritional intervention is required. Succulents should be fed only during their growing season (March through September). A cactus or houseplant food, fed at half strength, three or four times per growing period is generally advised. Any plant food with a high nitrogen value should be avoided.
Once the temperature warms up outside and the sunlight is plentiful, consider giving your succulent a holiday in the great outdoors. Acclimatize the plant to changes in light and temperature by taking the pot outside for increasing periods over a couple of weeks. Avoid the most direct, midday sunlight and keep a careful eye on the increased water requirements outdoors. Your plant's enhanced vigor will reward you!
It is very important to differentiate the non-active growth period of your succulents and to give them a rest. From October through February, most succulents need reduced water, food and temperature, though direct sunlight should continue.
Many succulents can be easily propagated by stem or leaf cuttings. The cutting should be air dried before placing the wound edge into sterile, barely-moistened sand. Water only lightly and transfer the new plantlet to a potting soil, sand, peat mixture once roots have developed.
For more specific information on a few popular succulent species, click on the tab at the top of this page.
Crazy about Cacti and Succulents by 
The Timber Press Guide to Succulent Plants of the World by 
