Through this short article, I would like to share my method of growing pygmy sundews, which has begun to give quite satisfactory results in recent years.
Most of these Drosera are endemic to Australia where they mainly occur in the western part of the country. The climate is rather subtropical with hot and dry summers, and fairly cool and humid winters, although temperatures are very rarely negative.
The vegetative cycle of the miniature Drosera consists of two main phases. Plants develop carnivorous leaves especially in autumn and winter, when soil and air humidity is high and days are short. On the other hand, the gradual arrival of summer temperatures combined with the drying of the surface layers and the lengthening of days cause the plants to enter into dormancy. The plants stop the production of new leaves and form a small and more or less hairy bud at the top of the rosette. Reducing the leaf surface exposed to dry winds and intense sunlight on the hottest days prevents the cells from drying out. The return of rains in the autumn also coincides with the formation of small spreading organs called gemmae, which once ripe, are dispersed by wind and water over the surrounding areas. Weather conditions permitting, a root emerges within a few days allowing the propagule to anchor in the soil, a phase quickly followed by the formation of the first carnivorous leaves. This "natural cloning" is an effective and fast means of reproduction.
Most species are easy to grow but it can sometimes be difficult to conserve some Drosera for more than one or two seasons. Watering is an important point. Pygmy Drosera require a very wet substrate during the growing season (autumn, winter and spring) while it should be kept barely wet during the resting period in summer. After many tests, I found that the use of tall pots (18 to 20 cm) greatly facilitated the management of substrate moisture and optimized the proper development of plants. Pygmy Drosera form roots that are remarkably long in relation to their size to exploit the lower layers of the soil that retain some moisture during the driest months. With such high pots, it is possible to leave a 4 or 5 cm depth of water in a large saucer to keep the substrate very wet during growth. The water supply can be reduced in spring by maintaining less than 1 cm or by letting the saucer dry completely from time to time in summer. The substrate must be fairly draining, composed for example of sand and peat (50/50).
The ideal temperature range during growth (October to May in the northern hemisphere) is between 5°C and 20°C. Plants can occasionally tolerate slightly negative night temperatures, provided the condition get significantly warmer during the day. In summer, Pygmy Drosera can withstand temperatures above 40°C but care must be taken to ensure that the substrate never dries completely and pot is kept from direct sunlight.
Pygmy Drosera enjoy full sunlight exposure. Artificial lighting devices such as fluorescent tubes or LED tubes also give good results, provided they provide sufficient power. The lighting duration should be between 12 and 14 hours in summer and between 8 and 10 hours in winter.