Download Growing Subtropical Drosera - International Carnivorous Plant Society

Growing Subtropical Drosera!
©International Carnivorous Plant Society
Growing Subtropical Drosera
Drosera species that could be classed as subtropicals are
found in South America, southern Africa, southern and eastern
Asia, and Australia. There are at least a hundred species of
Drosera in these regions. Some such as the tuberous, pygmy,
and wooly sundews of Australia and Drosera regia and a few
other Drosera from South Africa are special cases that need
to be considered separately because of their particular
requirements.
But most subtropical Drosera are just
variations on the same theme. They have been referred to as
DRS's or <expletive> rosetted sundews because they are so
hard to tell apart without ripping off leaves and checking
flowers and seeds under a hand lens.
Among Drosera species, the subtropicals usually make the
best terrarium and greenhouse sundews. They generally do
well in a moderate temperature range of 10°C to 35°C (50°F
to 95°F) and don't have dormancy or light cue requirements to
survive long term. They may need light queues to bloom but
you do not grow these Drosera for the flowers. Subtropical
Drosera do tend to prefer higher humidity than is typical in
houses and want more light than they can get on a window
sill. But there are successful growers who keep their plants
under artificial lights on shelves away from drafts.
Drosera aliciae. These plants are 5 cm
across.
Many subtropical Drosera are long lived. You can keep most
species indefinitely with repotting every 5 years or so. Even
annuals such as Drosera burmannii can live for years if you
remove flower stalks as soon as they appear. If the plants do
start to decline, propagating is easy from stem, root, or leaf
cuttings. Root and stem cuttings will give you new mature
plants relatively quickly. Leaf cuttings are not as quick but
faster than seeds.
Most subtropical Drosera aren't very picky about soil. They
can grow well in pure sphagnum moss, live, long fibered or
shredded, as well as the standard peat:sand "CP mix" which
can be anything from 30% to 100% peat. Growing plants in
CP mix with live sphagnum on top is very effective for the
larger or stalk forming species. Things to watch for are
inferior grades of sphagnum and peat and non-silica sand.
Read the bags carefully to make sure there is no added
fertilizer. The best sphagnum is from New Zealand and Chile.
For peat look for Canadian or German sphagnum peat. The
best sand is uniform size sand-blasting silica sand about 1.2
mm in diameter (16 mesh in USA).
Everyone has their favorite seed planting medium. They also
have anecdotes to tell why their way is so wonderful and the
way everyone else does it is, well, you know. You just have to
find what works best for you given the materials you have
available and the conditions you can provide. You can try a
high proportion of sand, putting sulfur in the soil, using
http://www.carnivorousplants.org/seedbank/species/D_subtropical.htm!
Drosera seedlings with one true leaf.
Drosera dielsiana. This plant is 3 cm across.
Page 1 of 2
Growing Subtropical Drosera!
©International Carnivorous Plant Society
sterilized material, waving a magic wand. They all work for
some people. And then there are pots. Don't get me started on
pots! Some people have obsessions about round vs. square,
tall vs. short, large vs. small. IT DOESN'T MATTER. Mostly.
One thing there is no argument about is you sow seeds on the
surface of your medium of choice. Don't burry the seeds. For
any seeds but bog plant seeds, you don't top water a seedling
pot. It can be fatal. With Drosera it is different. The soil surface
should be lightly misted after the seeds are placed. It helps
germination and settles the seed around large sand particles.
Make sure you label the pots and include the date so when it
seems like forever since you planted the seeds you can see it
has only been a few weeks. Some seeds may take a month
or more to germinate.
What you do next depends on what works best for you.
Everyone has their own preferred routine. I put pots with
seeds in plastic zip-lock bags under but not too close to
fluorescent lights. You could also use an aquarium in a
greenhouse. The purpose of the plastic bag is to maintain
very high humidity and to keep out fungus gnats. Fungus gnat
larvae will eat the seedlings. A temperature between 20°C to
25°C (70°F to 80°F) works best. The seeds should germinate
in a few weeks. When the new plants have a few true leaves,
you can remove the pots from the plastic bags and put them
in a bright terrarium or greenhouse. Or just leave them in the
bags for up to a year.
Most Drosera seeds are small and result in tiny, slow growing
seedlings. It takes patience to grow carnivores from seed. The
biggest problem in starting seeds is usually dealing with the
moss, fungi, and cyanobacteria (blue-green algae) found
naturally in the sphagnum and peat. It is not uncommon to
transplant seedlings into new media a few times as the
seedlings get overwhelmed with guk. Use a fine forceps,
bright light, and magnifying glass. Be careful not to damage
the roots.
Drosera madagascariensis from Botswana in
a 5 cm pot.
Drosera venusta from South Africa. This
species grows best under cool conditions.
Once the plants are large enough you can try feeding them
small insects or get some dried blood worms at a pet shop.
The dried blood worms can be dipped in water and placed on
the dewy leaves—don't feed a plant that isn't dewy. If the food
gets moldy, use less next time. A dab of 70% isopropanol
(rubbing alcohol) from a small paint brush will help control the
fungus.
Do not put fertilizer of any kind in the soil. If it it does not
directly kill the plants, it will change the soil chemistry which
may make the plants rather unhappy. Once the plants are
more than a cm wide they do respond to light misting with
dilute, high nitrogen fertilizer. It is best to use hydrated dried
blood worms on the leaves instead of spraying with fertilizer,
but if you feel you must use fertilizer, use foliar fertilizer with
care.
It can easily take two years to get mature plants. The hardest
part is getting the seedlings to a size you can feed them with
hydrated dried blood worms. Once you can do that the plants
should grow quite quickly.
Drosera trinervia.
-- John Brittnacher
http://www.carnivorousplants.org/seedbank/species/D_subtropical.htm!
Page 2 of 2