Some species of Drosera are so easy to propagate by leaf cuttings you can't help accidentally doing them. Occasionally you can find a pot with a broken leaf sprouting dozens of tiny plants. Occasionally. Not all species are what could be called easy and a lot of things can go wrong. But for most Drosera species, leaf cuttings are an easy and quick way to propagate plants.
Why do leaf cuttings instead of propagating plants from seed? Leaf cuttings will produce exact clones of the parent plant. There is a lot of genetic variation that gets expressed in seedlings. You generally need to start many more plants than you want from seed to assure you get a few that are vigorous in your growing conditions. Leaf cuttings may be your only option if you want an exact copy of the prize plant that is already performing well for you or you want to propagate a sterile hybrid or a plant that otherwise won't produce seed. As a bonus, leaf cuttings tend to produce mature plants quicker than from seed.
Not all Drosera species propagate readily from leaf cuttings. Drosera regia leaf cuttings are particularly difficult. For this species and many others with thick ropey roots, root cuttings can work well.
It is impractical to make leaf cuttings of pigmy and tuberous Drosera because the leaves are thin and tend not to make sprouts. The pigmies are usually propagated from the gemmae they produce seasonally. The tuberous species are best done by seed or sterile culture.
The Drosera petiolaris group species sprout new plants from the base of the leaf where it attaches to the stem. You need to pull off the leaf taking the stipule with it. When you do this you are taking a chance of damaging your plant. But of these species this is the only way to do it and even making perfect pullings is no guarantee of getting new plants.
The first requirement for leaf cuttings is having leaves in good condition. The best time for leaf cuttings is when the plants are growing vigorously. You want leaves that are fully open with lots of dew—probably the best 3 or 4 leaves on each plant.
Most Drosera species sprout new plants from the center or edge of the part of the leaf with the tentacles. It is painful to do this to the best leaves on your best plants but hold the leaf in your fingers and use a razor blade, scalpel, or dissecting scissors to remove the leaf somewhere along the petiole (non-dewy part). For species with long leaves such as Drosera filiformis you can cut the leaves into more convenient segments. It also is best not to cut yourself. Don't like slime with digestive enzymes on your fingers? Get used to it or wear exam gloves.
For wide leaves you can get more plantlets by cutting the dewy part of the leaf lengthwise. This is especially useful for leaves that tend to only produce one plant in the center of the leaf.
The second requirement for leaf cuttings is an appropriate medium for the leaves to live until they produce plantlets. Fortunately there are lots of options here.
The cleanest medium for leaf cuttings is pure water. Float the leaves, tentacle side up in a cm or so of pure water in a small jar with a plastic lid or sealed with plastic wrap. You can also put the leaves into a sealed test tube. Using test tubes is my preferred method. If the leaves are too long to fit, cut them into whatever length does fit. Make sure you use pure water. That is distilled or reverse osmosis water. If the water gets cloudy, change it. The advantage of water over other methods is the leaves will survive longer in the relatively sterile water. This is especially important for ones that are slow starters. When the plantlets have a few leaves like in the photos to the right, plant them in their preferred medium such as peat/sand. I like to bury them slightly with pure sand.
Other mediums to use for the leaf cuttings are live sphagnum, dried long fibered sphagnum, peat, peat/sand, or sand. In other words just about anything that you can grow the adult plants in. The main criterion is that the leaf cuttings need to kept very wet and should be partly covered by the medium to keep them in contact with it. You can put pots with the leaf cuttings in plastic bags or sealed terrariums, whatever will keep the humidity at 100%. The advantage of using mediums with peat are the peat can somewhat provide nutrients to the leaf and earlier to the plantlets. Live sphagnum is thought to protect the leaf cuttings from mold and provides a somewhat acidic medium. And you can leave the plantlets in the pots for some time as they are already in a preferred growth medium. The disadvantage of these media is they contain molds, cyanobacteria, moss spores, and other organisms that may interfere with the health of the leaf cuttings. Also the leaf cuttings may move and dislodge themselves so you have to watch things more closely. Make sure you put labels on the jars or tags in the pots with species name and other information along with the date. The date on the tag is very important. It is going to seem like an eternity until something happens in the pots and you can confirm that by reading the date on the tag.
The rest of the requirements for leaf cuttings are environmental: light, temperature, and time. The leaf cuttings need lots of light but you don't want to roast them. It is usually safe to put them under fluorescent lights but no closer than 12 inches or 30 cm. In a greenhouse it may be best to put them under the bench or in a shaded location. However there are species such as the tropical D. petiolaris group species that want rather warm temperatures.
Now comes the real hard part: waiting and waiting and waiting. Nothing much is going to happen for the first month or so. D. filiformis and D. binata may explode out fairly quickly the second month but others like D. slackii could hang on for 5 months and then condescend to do something for you. Maybe. Not all leaves will make it. You may want to remove ones that totally turn brown or get fungus. But do not give up and definitely don't begin mourning if there is any green or red left on the leaves.
The thing that amazes me most is where the young plantlets sprout. It totally blew my mind to see the D. spatulata plantlets sprouting from the center of the leaf. I was told that is what would happen but I still was not prepared for it. Right out of the center of the leaf!!! Other species like D. prolifera do sprout near the leaf edges where I expected but they will do it from leaves that look like toast! And then there is D. binata. Stand back! The plantlets can be spaced one or two mm apart on the leaves. But most Drosera take their time, produce a few plantlets, and grow slowly.
-- John Brittnacher
Drosera spatulata plantlet growing out of the center of a leaf cutting. Usually you get one plant per leaf.
Drosera prolifera is an easy species for leaf cuttings. The old leaves are red but still with dewy tentacles 4 months after being cut off the plant.
Leaf cuttings in 16 x 125 mm plastic test tubes with caps. A plant tag with the name of the contents and date the cuttings were taken is rubber-banded to the tubes.
Drosera x hybrida leaf cuttings in small jars of pure water. This is the only way to propagate this sterile hybrid.
Drosera binata leaf cuttings in a tube of water ready to be planted out.