Propagation of tuberous drosera
In this chapter I will introduce you to the different ways to propagate tuberous drosera. As this is a large topic, I put the seed germination guide and the flower pollination topic in separate sections.
Formation of daughter tubers
Some species produce additional tubers ad the end of every season, like Drosera aberrans or Drosera menziesii ssp. menziesii. This may happen either by forming more than a single tuber at the main stolon (like Drosera menziesii) or by the formation of additional, often lateral stolons as described for e.g. Drosera aberrans.
To make things a little more complicated some species show a variable behaviour depending on the clone or the form with some producing additional tubers frequently and others never or only rarely. One prominent example for different behaviour of variants is Drosera macrantha ssp. macrantha. All the plants with the description 'Rock Outcrop Form' in my collection very reliably produce additional tubers each year whereas as for instance my 'Northern Heathland Form' never did so in eight seasons so far. Another example is Drosera lowriei 'giant plants': I originally bought 3 tubers of that form over several years. Two plants seem to produce a larger tuber each year now reaching more than 2 cm in diameter but never produced any daughter tuber. The third plant which seems to divide into at least two tubers of about equal size each season or one large tuber and several smaller ones. This clone has tuber sizes of about 1 cm in diameter for the larger ones. Interestingly, the plants have the same size and seem to produce about the same number of flowers each season despite the differences in tuber size.
Finally, there seem to be years where species, which rarely produce daughter tubers, suddenly produce a larger number of additional tubers. One example for me was a Drosera zigzagia which so far in one season (out of 6) produced 7 tubers and in all other seasons no extra tubers. For whatever reason the season 2011/2012 was quite good for such behaviour as I had several plants producing additional tubers for the first time in many years.
Often tuberous drosera are referred to as being difficult to grow from seeds. This may be true in some respect for a few species, like Drosera ramellosa, but for most species it is not really much of a problem. If you do not believe this, please try the methods described in my germination guide.
However, often it takes several seasons until the plants reach flowering size: 3-5 years is usually a good guess for this.
The germination guide intends to summarize my observations and methods for the germination of tuberous drosera. The methods described in the following section will work equally well for winter growing south african drosera. My intention is to have an easy and general procedure for germinating seeds of these interesting species. The methods described below will work for most species but there are some species I did not have much success with in the past: Drosera ramellosa and Drosera lowriei are such examples. Other methods (or more patience) may be more successful for this one.
Other methods of propagation
There were several reports on the propagation of tuberous drosera species by leaf cuttings. Namely, the Drosera aff. tubaestylis Brookton form seems to be suited for this. However, I do not have much experience of my own with this method.
Somewhat accidentally I noticed some other behaviour which may be used for propagation if one is willing to risk a loss of plants: With one shipment I received a packet of Drosera macrophylla ssp. macrophylla tubers. They were about 1 cm long in case the size is important. When they arrived, most had already started to sprout and the stolons were about 1 cm long. The disaster - at least in my eyes - was that one of those stolons was broken off at its base. Not knowing what else I could do I planted both the stolons and the tuber and to my surprise both developed eventually into nice plants and formed new tubers at the end of the season. I expect one can use this regenerating capability to propagate those species which do neither produce additional tubers or seeds, or if a second clone for pollination is not available. This so far is a single observation and other growers report similar observations. However, I never tested whether the regeneration capability is reliable enough to be used for propagation purposes.
Finally, in similar fashion one can try to break the stolon while the formation of a new tuber has started. Sometimes, the plants may start to produce a new tuber after the first is broken off. However, as I damaged stolons much too often at the end of growing seasons, my general impression is that this may be successful in some cases but more often than that it will fail.