Subtropical South-African Drosera are amongst the easiest to grow as they are very vigorous and tolerate a great range of growing conditions. They make a great set of species to get the hang of Drosera cultivation. Harder species will often require similar conditions with only a few settings to change.
There are different types of South-African Drosera but here we will only focus on those that could be qualified as "subtropical". Other articles will focus on different groups such as the winter growers and the annuals. To clarify things, here is a list of concerned species:
- Drosera admirabilis
- Drosera affinis
- Drosera aliciae
- Drosera burkeana
- Drosera capensis
- Drosera collinsiae
- Drosera cuneifolia*
- Drosera curvipes
- Drosera dielsiana
- Drosera elongata
- Drosera ericgreenii*
- Drosera esterhuyseniae*
- Drosera flexicaulis
- Drosera humbertii
- Drosera madagascariensis
- Drosera natalensis
- Drosera nidiformis
- Drosera ramentacea
- Drosera regia
- Drosera rubrifolia
- Drosera slackii
- Drosera venusta
* can also be cultivated as winter growers
These plants can be grown almost everywhere: indoors, greenhouse, terrarium and sometimes even outdoors! You can keep them going all year round if the conditions are suitable. But if it gets too cold too dry during winter, the plant might stop growing and sprout back from the roots in the spring.
Soil composition and container
Both long fibre sphagnum moss (LFS) and peat can be used as an organic base for the soil, peat being the most commonly used as it is way cheaper. Look at the composition written at the back of the peat's packaging and make sure that it is sphagnum-based (often called "peat moss") and that there are no added fertilizers.
It is recommended to mix around 30% of perlite and/or quartz sand to this organic base as to improve drainage and aerate the soil. Quartz sand is often found in aquarium stores or pool stores where you can ask for "pool filter sand". Make sure to wash it thoroughly before using it to remove any dust that could be harmful to carnivorous plants and promote algae growth.
Any kind of pot can be used except the unglazed terracotta ones, as they can leech minerals into the soil over time. Although some of these plants have an extensive root system or very thick roots, they do not mind being a little bit root-bounded. If you notice roots coming out of the bottom of the pot, it might be time for a size upgrade. I personally use 7x7x8cm square plastic pots except for Drosera regia which needs a larger container to reach its maximum size.
Air temperature and humidity
The optimal daytime temperature is anywhere between 16°C (43°F) and 30°C (86°F), but they can easily sustain in temperatures up to 38°C (100°F) and down to 5°C (41°F) for a few days. Go lower than that and plans will often die, especially if they experience frost. The good news is that most of them have thick roots that will grow back in springtime. A lot of people grow these plants in unheated greenhouses and consider them as annuals.
Humidity is not very important as long as it not too dry. Anywhere between 40% and 100% be fine.
The easiest way to water them is to use a tray beneath the pot, always filled with 2-3cm of water. Only ever use water that has a low PPM (Parts Per Million) such as rain, distilled or reverse-osmosis water. Usually, tap water is way too hard for carnivorous plants but you can always use a TDS meter to measure the PPM of your house's tap water. I would advise not to use any water that has over 50 PPM.
If you are growing them in an unheated greenhouse, remove the tray but keep it moist during the winter to avoid root rot.
The more light, the better! If you are growing them outside or in a greenhouse, you can give them full-sun all day long. Indoor growers, do not underestimate the amount of light these plants need. Either place them on a windowsill that gets direct sun multiple hours a day, or give it additional light with the help of artificial lighting. Home ceiling lighting is
Not sure if your South-African Drosera is getting enough sun? There are a few indicators of lack of light that you can check for:
- No glue is produced by the leaves. This is a sign of severe lack of light, move it to a brighter place as soon as possible
- The plant is stretching towards the light source. This is called etiolation, move your plant closer to the light source.
- Leaves are green. These Drosera produce anthocyanin when getting enough light, which gives them a red colouration. Green plants can survive if they produce dew and are not etiolated.