Cultivation Tips

Growing succulents can be one of the most challenging and rewarding endeavors for both the amateur hobbyist and professional grower alike. Even after years of growing, I am still astounded by the stark and intricate beauty that nature assembled in this class of plants, and the degree of specialization found is truly awe-inspiring. This is both what makes them so unique and also what often makes them somewhat difficult to grow. Many of the frustrations involved can be avoided by a simple understanding of a few basic concepts. Of course, there are exceptions to every rule, but in general most succulents have many characteristics in common. The point of this article is to discuss them in a simple straightforward way. The most important thing to consider is where a particular plant comes from. Does it come from a wet or dry area? When is the rainy season? What type of soil does it grow in? Considering a plants natural habitat will give some important insights into their proper cultivation.

General Care Instructions

Soil

This is always a subject of much argument, but really it’s much simpler than one might think. The vast majority of succulents will do fine in your standard peat/bark based potting soil with the addition of about 30% perlite or pumice. Make sure to avoid potting mixes that advertise moisture retention components. For those of you that want to mix your own soil, a reasonable mix can be had by adding 1 part peat or coir (or ½ of each), ½-1 part fine decomposed bark, and 1 part drainage/aeration material (pumice, perlite, turface, etc. or any mix of these). Please note that sand and gravel are not included here. Sand will hold water unless it’s very large, and gravel merely displaces water holding capacity while providing no aeration. To this add some granular, time release fertilizer. If your local water is low in mineral content, you might consider adding a very small amount of pelletized lime or a small amount of limestone grit. This will help buffer acidity as the organic components break down. For those plants that prefer a heavier soil, some poor garden soil can be added. Be aware though that this practice may transmit all sorts of pathogens. Steam sterilization is possible, but never works completely.

Water

Watering depends on a number of factors including temperature, humidity, season, the type and size of the pot, etc. Basically, when plants are actively growing, they should have consistent moisture. This may be low, moderate, or ample moisture depending on the needs of the plant, but they should not be allowed to dry out completely. When plants are dormant, they should receive infrequent, light watering and can be allowed to dry out in between (often for long periods). Overwatering plants during the dormant period is the number one reason for casualties. Under watering during growth is number two.

Exposure

This depends entirely on the plant in question, but in general- the larger the mature size of the plant, the more sun it probably needs. This is due to the fact that as plants become larger, the availability of solar protection declines. So trees are more likely to need full sun than are small stem succulents. In cultivation, most succulents will do best in what we call broken shade. This is about what you would find under a native mesquite tree in the Southwest US. Sunlight does filter through the leaves, so it’s not a true shade. It’s equivalent to about 30-50% shadecloth, depending on your location. Part sun is also acceptable to most succulents, but an eastern to south eastern exposure is usually favored by smaller plants. Many trees and shrubs can also survive on part sun, but usually prefer a south to southwestern exposure. Please note that your location can dramatically affect the meaning of 'full sun'. Full sun in Arizona is VERY different than full sun in Washington.

Temperature

For most succulents, the most acceptable range is between 60-65F and 95-100F. Outside of these temps most plants tend to become stressed in one way or another, and often become more susceptible to disease. Any time temps are out of this range on a consistent basis, watering should be lowered slightly.

Dormancy

Succulents display a wide range of dormancies, ranging from opportunistic growers, to cool weather growers, to warm weather growers, to spring/fall growers. Opportunistic growers will grow basically any time of year as long as temps are within a given range and water is available. These plants pose little problems. Cool weather growers tend to grow fall through spring and usually observe a pseudo-dormancy in the dead of winter. Warm weather growers grow from spring to fall and may or may not observe a pseudo-dormancy in summer. Spring/fall growers tend to observe a fairly strict dormancy in both winter and summer. Usually these are plants being grown outside their normal temperature range in both summer and winter. So, the main thing to understand about dormancies is that water requirements are lower during dormancy or pseudo-dormancies. As the plant is not actively growing, water is only required to keep roots healthy and to stave off desiccation. Generally, there are a few things to consider. First, the further outside the temperature range the plant is (hot for winter growers, cool for summer growers), the more strictly the dormancy will tend to be enforced. This means summer growers need very little water in an extremely cool winter, and vice versa. Second, the more woody a plant is, the more regularly it will need light water during dormancy. Third, the larger the water storage capacity, the longer a plant can go without water. This means the amount of succulent tissue relative to the size and type of plant. Many mature caudiciforms can go through their entire dormancy without any water. All of this makes for a seemingly complex issue, but generally two rules should be followed. First, make sure to separate your plants by dormancy period (it’s ok to simply call them winter or summer growers). Second, water all dormant plants lightly at least once every 30 days. Following these two simple rules is usually enough to avoid tragedy. Fertilizer- Of course plants need food. If you have the means for ease of application, light fertilization with every watering during the growth period is best. About ¼ - ½ strength will do wonders. If you are fertilizing more infrequently, use about ½ strength. Any balanced food with micronutrients will do fine (10-10-10, 20-20-20, etc). Fertilizer should never be applied during dormancy.

Pests

The number one insecticide in my opinion is Imidacloprid, which is available in a number of preparations at most hardware stores. The liquid preparations are the easiest to deal with, but granular types can be added at transplant time as well. This is a systemic insecticide which is usually applied as a soil drench. It lasts 4-6 months, is relatively safe, and treats most common pests except mites. Make sure always to treat your ENTIRE collection. If you treat only a portion, the pests will simply move. For mites, the safest approach for the hobbyist is insecticidal soap. It requires repeated applications to bring populations under control, but is far far safer than commercial miticides. Avoid neem oil, as it can damage softer succulents.

Transplanting

Just a short note- When you receive your plants, it's usually best to pot them up in dry soil and wait a couple days before watering. This allows time for any wounds incurred during bare-rooting and transplant to heal, and dramatically reduces the chances of fungal attack.