Drosera regia, the King Sundew - one of the rarest in the wild and highly esteemed in cultivation.
Drosera regia is in the top three of the largest Drosera (in terms of biomass) discovered so far along with the recently discovered Drosera magnifica and the Australian Drosera gigantea.
Compared to most over Droseras, The King Sundew is a large, massive plant with dominant appearance. A truly royal presence as the name regia suggests.
In nature it is found growing in only two locations in the Bainskloof Range near Wellington, Western Cape in South Africa. The populations are small in both locations.
Scientists say that Drosera regia is one of the most ancient Drosera species alive today. It shares some genes with Dionaea and is incompatible with other Drosera species so no hybridising is possible. As a great admirer of the species, I like this restriction. For me this plant is simply perfect as is.
The leaves are long (up to 70x2 cm.), linear, light, yellowish green with a tint of red on the base and midrib. They lack petioles and the point at which the stalked glands begin to grow varies from plant to plant. In my collection there are plants with greener, broader leaves that have glands nearer the bases of the leaves and plants with yellowish green, narrower leaves with much stronger red coloration, especially on the midrib, with glands starting to grow further on the leaf. These features resemble plants of both natural locations. The glands are red. On younger leaves their stalks are also red, on older leaves - green or yellowish, but nearly colorless, translucent. The leaves are very flexible, capable of folding over the prey several times, forming all kinds of knots. Drosera regia produces lots of dew and when the air humidity is high the leaves are so heavily loaded with dew that they droop and drool. Old leaves remain attached to the plant as a skirt and disintegrate very slow, maybe acting as a mulch in an attempt to buy the mature plant a little private space.
There is a very interesting phenomenon, that I call "bleeding". It is not specific to the King Sundew, it occurs on other Drosera species and on Drosophyllums too, but it is more dramatic on regia because of the big leaves and bigger dew drops. When a particular leaf starts to die naturally the senescing starts from the tip of the leaf. The digestive glands gradually die, while the dew is still on them. Cells rupture and release pigments into the dew, making them look like drops of blood. I don't know if that portion of the leaf is still capable of absorbing and if the plant recycles some nutrients in this way, but it may be possible. It is a spectacular sighting. The bleeding part moves down the leaf while it dries up.
Flowers of Drosera regia are pink with darker veins, yellow-green throat and bright yellow stamens. They are a delicate perfection! Bracts have short, but functioning glands producing mucilage. Flower color also varies from saturated pink to pale pink.
Well developed seeds are black, about 2 mm. long, visibly swollen where the embryo is. They are shiny but with some relief to them so they look like satin to the naked eye.
Cross pollination is required for good results. Self pollination may work under some circumstances, but the result is inferior seeds and a large percentage chaff. Producing inferior inbred offspring of an endangered species is not wise even if it is possible to some extent so don't try to self pollinate your Drosera regia.
The rhizome is woody, grows almost horizontally slightly above the soil level, supported by aerial roots and often has multiple growing points, somewhat similar to the way Sarracenia rhizomes grow, but fully exposed above ground. The roots are thick and fleshy, very long, black in color. Only the active growing root tips are in a dull yellow color. There are some thinner feeder roots too that develop usually near the bottom of the pot.
Maybe because they are so ancient, I don't really know, but these Droseras are exceptionally good hunters, way better than any other Drosera species I have ever seen (in my collection only Drosera binata comes close). During the summer the leaves of the King Sundew are literally covered with flies so that they have almost no free tentacles left and are looking black, covered with their victims bodies.
In nature Drosera regia grows amongst grasses on sloped, rocky terrain with constantly seeping cold water. The area has a subtropical climate modified by the relative high elevation - Bainskloof pass is at 594 m. altitude. Temperatures are moderate, frosts are rare and brief. Nights are cooler than the days with the nighttime temperatures rarely exceeding 20℃. The seeping water keeps the roots even cooler. The most rain falls during the winter. The shortest days are about 10 hours, the longest - about 14 1/2 h.
If you can provide nighttime temperatures below or around 20℃, lots of sun and fresh air year round with cooler, but relatively frost free overwintering you have the right conditions for the King Sundew. Although in their natural habitat daytime temperatures rarely exceed 36℃ in my cultivation the plants endure up to +45℃ during the summer days without any harm, but again - nights are about 20-22℃ or below and this is important for the long term survival of these plants. Because of the correlation of the night time temperatures and altitude (nights are cooler at high altitude regardless of the surrounding climatic zone) it means that under natural conditions Drosera regia will not grow well in lowland tropical conditions. It does well for me at 850 m. a.s.l. with the lowest limit possibly being about 300-400 m. above sea level in temperate and subtropical zones, lower in cold temperate zones, higher in the tropical and equatorial zones.
Propagation and further cultivation
The easiest way to establish this species in your collection is through seeds. Unlike most other Drosera species, D. regia has quite big seeds. They are easily manageable and produce bigger, stronger seedlings. Germination occurs in 10 days under favorable conditions. The cotyledons are exposed and don't have glands. The first true leaves are alternate in arrangement and capable of catching prey.
Seeds of Drosera regia can be sown year round, they are quite easy germinators actually. The one thing you don't want to do with them is place them in a constantly heated propagator at high temperatures. Fluctuating temperatures, 10 or more degrees Celsius difference between day and night is a major clue for germination. Temps of about +15 to +25℃ work good. In climates with hot summer temperatures the best time to sow them is the autumn because of the natural temperature fluctuations and the longer time the seedlings will have to establish before the summer heat.
Use good quality substrate suitable for carnivorous plants. The ingredients that I use in order of preference and volume are: shredded pine bark, perlite, peat, coarse and some fine river sand free from salt and lime. It is important to soak the perlite in a bucket of water and discard the heavy sediment that falls at the bottom. The substrate should contain a good amount of larger particles, be very well drained, lightweight and airy - water poured over it should drain instantly. Do not use substrate that consists only of equally sized particles of any kind. I use milled pine bark as the main ingredient. Dried sphagnum moss can be used, but do not use live sphagnum moss, it could overgrow the seedlings. Moisten the substrate thoroughly.
Sow the seeds superficially, widely spaced, ensure good contact with the substrate. Do not bury them.
Place the container outside in a bright position and keep the surface of the substrate constantly moist until germination. You can cover it with a piece of glass to increase humidity, but then avoid direct sunlight or else you can cook the seeds in a matter of hours.
Beside seeds, root cuttings are easy and work well. Take a peace of a fleshy root, a few centimeters long and lay it horizontally on a suitable substrate, cover it lightly and keep moist. I don't bury them too deep - 1 cm. or so maybe, just enough to be firmly fixed and kept moist all the time. They will sprout even if buried deeper, but will fail if exposed and dried. Emerging above the gound can take up to a few months depending on the time of the year. Once the new plants are big and strong enough, having roots of their own, they can be replanted separately.
Propagating Drosera regia from leaf cuttings is also possible, but more difficult. I have seen photos of plantlets successfuly developing from a leaf, but I haven't tried it myself. You can take a portion of a leaf and lay it on chopped live sphagnum saturated with water and cover with glass to retain humidity. One of the main problems I see with this method is how to keep the media clean from algae, mould, cyanobacteria and so on. The other important factor I think would be the leaf selection and timing. You don't want a leaf that's nearing the end of its natural life cycle and you don't want to do it when dormancy is ahead (regardless if it is induced by unfavourable environmental conditions or natural). Otherwise if you can keep the leaf healthy and alive for long enough you should succeed.
Drosera regia does not like to sit in standing, stagnant water and having the rhizome constantly wet. The rhizome grows naturally above the soil level and should be left this way. If you want for some reazon to cover the rhizome you can do it only with pure gravel, otherwise in more water retentive substrate the rhizome should be exposed above ground. Covering it with peat, sphagnum and such or otherwise keeping it constantly wet may cause rot.
At the same time seeping cool, pure water through well drained substrate is best for the roots. That's why I top water them and don't use trays. However they will grow well in a tray of water if planted in very deep pots so that the rhizome is well above the water level and the water is refreshed regularly like when the tray overflows during rain or during manual watering. Well established plants take root disturbance well, but avoid it with young plants and use deep pots. During the summer top watering with cold water in the middle of the day helps in keeping the roots from overheating. I grow my king sundews in very tall (25 cm) black plastic pots with lots of drainage holes. In my climate black plastic pots work well even in full sun and there are no problems with substrate overheating but I live on a northern slope at 850 m. a.s.l (Northern Hemisphere). In hotter climates you may need to take extra precautions to keep the roots from overheating like using white pots, wrapping pots in reflective material or using styrofoam boxes with drainage holes as pots, shading the pots without shading the plants, placing bottles with frozen water around the pots or ice on top of the substrete or grow them entirely in dappled sun. Drosera regia requires strong light - so try to give them as much sun as possible without overheating the roots.
Depending on your climate your plants can have one or two dormant / semi-dormant seasons - during the hottest weeks in the summer and the coldest time in the winter. During these periods they lose their leaves and only small buds of underdeveloped leaves remain on the growth points. As long as these buds are healthy, fresh, firm and with good color the plant is fine, just dormant. When the time comes these tiny leaves will resume growth. You'll find photos of dormant plants in the gallery. If however everything turns black then this is not dormancy, instead it means that the rhizome or at least that portion of it has died. Usually though you can count on new growth from the roots or other/lower parts of the rhizome that were unaffected (if there are such unaffected parts which will depend on the cause of the problem). So don't give up hope easily!
If you sow in autumn it is good to avoid the first winter dormancy and have established plants before the summer heat.
Many sources perpetuate the statement that Drosera regia requires heavy feeding and even fertilizing or else plants may die from starvation. Many people believe that not feeding them is the reason why seedlings fail to establish. I don't think this is the case though. First we are talking about plants, they photosynthesize and second they are capable of catching abundant prey since early age. Also they do feed on much more than insects. Organic matter, even in the form of invisible dust (think of pollen for example) is a source of nutrients for them too. Of course if you grow them in a small enclosed space they have access to far less natural food and might really suffer from starvation. In this case and also during periods with less prey you will have to feed them indeed.
I never fed my plants during the first 3 years of their life, but then we had a season with very few insects flying around and I started experimentally feed them. I tried a few pellets of Osmocote Bloom in the pot, didn't like the effect and will not do it again. The plants didn't get bigger, didn't grew better, only the leaves got curly. Eventually I came up with my own recipe for a mixture of Chlorella, Spirulina, bee pollen, Kelp powder, inactivated brewer's yeast that worked good applied as a spray, but it's costly and I abandoned it. Betta fish food is also an option. Spraying with weak solution (0.5-1.0 g/l) of MaxSea fertilizer works very well and is the easiest and cheapest solution. A couple of very light applications of a fertilizer only with microelements (no NPK) at a rate of no more than 100 µS/cm alo works well. The one I use has MgO:10, B:1, Cu:1.50, Fe:3.75, Mn:2.50, Mo:0.05, Zn:0.50. It could also be mixed with the MaxSea at a lower rate. Kelpak (the South African one!) is a product that I like a lot. It is not exactly a fertilizer though, because it is very rich in natural growth hormones, not just mineral nutrients. If needed it works great applied as per the label (1:500 to 1:250). Of course for a small collection the best thing to do is feed them live insects. Many people feed their sundews with dried bloodworms, but I didn't find them here so I haven't tried them. Lately (2021) I just water them once in a week with MaxSea solution that has enough fertilizer in it to turn the solution nearly opaque. Coupled with the usual regular flushing of the substrate with clean water it works very well. If you don't have the habit of regularly flushing the substrate with clean water I strongly suggest that you start doing it, regardless of whether you fertilize or not - it is always a good thing to do! More of my experience with fertilizing carnivorous plants is described here: fertilizing carnivorous plants.
As you can tell, I am pretty excited about the King Sundews and I am sure you share my passion too!
I invite you to look at more pictures of Drosera regia from my collection here:
more Drosera regia photos
Author of the text and photos: Petar Kostov, telopeanursery.com, 20160605, updated June 2021.