Haworthia cultivation

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Haworthia are native to regions of South Africa where it rains mostly during the winter. I have found that for me they tend to grow all year and may go dormant during the coldest part of winter and if there is a prolonged heat spell during the summer. They seem to love it when the temperature is cooler but need to be protected from hard frost. They do well with the cool summers of the California Bay area.

Soil: I grow them in mostly pumice (probably about 80%) with the rest being equal parts of decomposed granite, loam soil and “builders sand” (it’s more like gravel than sand). You can also use coir. A tiny bit of gypsum helps condition the soil and provide calcium. I always add a layer of decorative pebbles (small sized salmon bay pebbles) because it looks nice and also helps keep the mix from drying out too quickly.

Watering: Water about once a week to once every two weeks all year.

Feeding: I use a fertilizer I buy in hydroponics stores. I like the flora series from the General hydroponics brand. The concentration I use in ½ strength their recommended concentration for seedlings. I also use will occasional fertilize with a silica fertilizer (Silica Blast) and calcium chloride.

Light: Proper light is essential to good Haworthia cultivation. Plants grown with insufficient light will be green. Too much sun can also be problematic. The trick is to give them enough sun to bring out their nice colors and not much more than that. Several hours of morning or late afternoon sun is best. Protect from strong sun during the summer and during the transition from winter to spring. Since Haworthia are winter growers making sure they get enough sunlight during the winter months can be challenging and is important to keeping them attractive looking. Mine are in a north facing exposure and get full sun until about 10:30 or 11:00 AM depending on where they are situated.

Pests: Haworthia are generally not as susceptible to the mealies as some other succulents. I periodically treat the plants with Imidoclaprid, a neo-nicotinoide insecticide to prevent infestations of mealies, fungus gnats and thrips. Thrips are an especially bad pest for Haworthia. They bite the leaves and transmit pathogens that cause leaf stunting and can make the leaves rot. If they bite a flower stem it often will wilt. A friend recommended Spinosad which is a relatively safe and effective treatment for thrips. I apply Spinosad in the spring which is when thrips seem to be the most active and damaging.