It’s no secret that succulent plants are successful growers. Over 10,000 succulent varieties can be found around the world, in such difficult habitats as mountain tops, desert expanses, jungles, even on rocky coastlines. They are so widespread because they have adapted to survive by creatively conserving their most precious resource: water.
The ten main succulent groups don’t look much alike. Cactus plants are distinguished by their spikes that conserve water loss and protect them from predators – but these look very different from the fleshy lobes of jade plants, the tree-like crassulas or the strange convolutions of euphorbias. In spite of their different appearances, succulents have common needs for light, temperature, water application and planting media, and this makes them an easy choice for home gardeners.
As they have adapted to the availability of water, succulents have also evolved to react to light conditions. The home gardener should be careful to provide enough light without burning the leaves or causing growth to become spindly. A window with gentle eastern exposure is best; for south-facing windows with bright light, a sheer curtain can cut the amount of light to a tolerable range. Outdoor pots can be moved for maximum advantage and may need to be placed in light shade during hot sunny days. Plants in a greenhouse or cold frame will need a shade cloth.
All succulents need good drainage, whether in pots or planted in the ground, and should never sit in water. Adding rocks that provide shelter and gaps in the soil is a good choice outdoors. Amendments such as gravel, lava rock and pumice will also lighten heavy soils so that the plants can survive periods of high rainfall.
While most succulents thrive outdoors in dry, arid areas with hardiness zones of 10 – 12, Southside landscapes show off a few varieties such as agave, prickly pear and Sempervivums that make it through our winters once they become well established. Tender, fleshy succulents tolerate high temperatures (ideal daytime temps of 70-85° but up to 100° if provided a little shade), but they don’t do well with frost, ice and snow. The worst conditions are high rainfall with freezing temperatures, which can rupture the plant cells making them look like they “melted.” Cover outdoor plants with fabric tarps or frost cloth during cold snaps or bring pots indoors to sunny windowsills.
Indoor plants should be watered well during summer months and allowed to dry out between waterings. Signs of overwatering are yellowed or discolored leaves that become soft. It’s likely that the roots have rotted, so take a cutting and repot in a drier container. Plants that have been underwatered will stop growing, shed leaves and may have leaf spots. During winter months, indoor plants should be given a break and watered only once a month. Note that glazed pots retain moisture longer and unglazed pots allow for quicker evaporation.
Being the survivors they are, succulents don’t need a lot of extra nutrition. They can be fed a quarter-strength water-soluble fertilizer once a month during the spring/summer growing period. Don’t feed at all during the winter. Commercial cactus mixtures may be OK for true cacti but not so much for other succulents. An easy potting mixture is half potting soil and half sand or perlite. Small amounts of bone meal can be added.
Propagating succulents is also easy. Some will grow from leaf cuttings where the whole leaf detaches from the stem and starts a new plant. Others will shed stems that can be allowed to dry off and heal over or callous before being placed in the potting medium to put out new roots. Drying succulent cuttings before replanting prevents root rot. Clumps can be divided using sterilized tools and allowed to heal over before replanting. Succulents that produce “pups,” such as aloe, can simply be gently separated from the parent plant, allowed to dry off and given their own containers. Once replanted, put the new pots in indirect light and don’t water until roots have formed. For outdoor agaves, a large rock placed next to the plants can absorb heat during the day and give shelter from winds.
Succulents will be for sale at the Southside Master Gardener Plant Sale on Saturday, May 1, 7:30 am to noon in the parking lot of the Halifax Library on Main Street in Halifax. Several varieties will be for sale. If you want to guarantee that you will succeed with succulents, pick up one of the painted “rock garden cactus” which require no care at all on a desk or bookshelf. There will be plants of all kinds for sale and bring your gardening tools for a cleaning and sharpening.