Propagation of Nepenthes

There are 2 main ways of propagating Nepenthes. The first and easiest is by by taking cuttings, the second is to grow them from seed. I haven't included tissue culture here as it is not a readily accessible means of propagation for most collectors.

Cuttings

Many Nepenthes are very easy from cuttings, particularly lowland species. Most highland species will strike quite easily, but some such as N. burbidgeae are notoriously difficult (and some ultra-highland plants and hybrids are reported to simply not grow from cuttings).

I will include removal of basal shoots under this rubric. Basal shoots grow from beneath the growing medium and can be removed to make a new plant. Sometimes they come with roots, other times they're shoots from underground nodes, so come off like any other branch.

Cuttings are easily made from the climbing stem once the plant has started to climb (although in scrambling species you'll have to wait for the stem to be long enough to cut. A piece of vine including 2-3 nodes should be cut with a very sharp knife - care must be taken not to crush the stem during cutting as this can impede rooting. In some species a 1 node cutting can be made, but leaving 2 nodes provides a greater chance of survival if one node proves unviable.

There are different methods of preparing the base of the cutting - it can be cut into a 'V' shape, or a cross can be sliced about 1cm into the bottom. Slicing the stem at a diagonal increases the surface area therefore increases the surface area from which roots are formed. Where a branch has been removed from a main stem, I've found the heels root fine without preparation.

The base of the cutting can be lightly dipped in rooting hormone - there is debate as to whether this facilitates rooting in Nepenthes. I've made cuttings both with and without rooting hormone and haven't noticed any difference. The cutting can then be placed in moist spagnum most, and kept in high humidity. A good method is to place it in a pot of spagnum moss, then place the pot inside a plastic bag until rooting occurs. However, if you have a greenhouse or live in an area with humidity above 50%, the cutting should be fine as is. I take most of my cuttings in spring and summer, and simply place them outside. I would avoid keeping the cutting in extremely high humidity for too long (above 90%), as that can encourage rot.

If there is a fully developed pitcher on any of the leaves, fill it with clean water as this helps keep the plant hydrated. Otherwise where no pitcher or an undeveloped pitcher is present, cut the end half of the leaf off to avoid transpiration (losing moisture from leaf pores), the less surface area there is the less moisture is lost.

Roots appear in around 4-6 weeks, and the new plants can be potted up in 3 months if need be.

Some easy lowland species like gracilis can even be grown from cuttings by placing the cut end in a glass of water. This method generally does not work for highland plants, and I find spagnum the most convenient medium.

Word of warning! Try to avoid cutting a vine which has no branches or basal shoots. I know of growers who have killed an entire plant by cutting off the growing tip of a vine which hasn't already got a second growing point.

Seed

Growing Nepenthes from seed is not a terribly difficult proposition for the most part, particularly compared to other carnivorous plants such as sarracenia which need stratification. However, Nepenthes seeds do have their challenges. The reason for this is twofold. Firstly the seed of many Nepenthes species has a very short window of viability (bicalcarata and gracilis seed can lose its viability in a matter of days) certainly a couple of months will see a significant drop in viability in many Nepenthes species. However, I have heard of eustachia seed being sown 1 year after collection and having a 60-70% germination rate. The second reason is that the mortality rate of seedlings can be quite high due to rot and fungal attacks.

Nurseries grow their seed the scientific way, they treat the seed with fungicide then sow them on a sterile nutrient solution in flasks. That way ensures better survival of the seeds that germinate, as fungal attacks account for quite a bit of seedling loss. But for the rest of us, it is not an available or convenient solution.

Nepenthes seed should be sown sparsely on an appropriate medium, such as spagnum moss (either reconstituted dried spagnum or live, but the live spagnum will overgrow seedlings and needs to be trimmed) or a mixture of 1 part each of peat moss, perlite, vemiculite and fine grade pine bark. The pieces should be not much bigger than the perlite.

Germination can take anywhere between 3 weeks to 3 months, and sometimes nothing can happen for a year - you need to be patient, and not throw them out for about least 15 months if they haven't germinated. The seedlings are absolutely tiny when they sprout, and the cotyldons have the same shape as those of tiny little tomato plants.

Provided the seedlings are not too cramped, I would let them grow at least for a few months before planting up, but the longer the better in my view. However, it is a good idea to pot them up once they start to overgrow each other.

However, growing Nepenthes from seed, particularly highland species, needs exemplary patience, as they grow very slowly and take years to mature. After one year, some species may only have grown 2 or 3 little pitchers, so you can imagine how long it takes to get to a decent size rosette.

Given that so many of the plants these days are from tissue culture (and thuse from a very restricted gene pool), I try to grow as much species seed as possible to increase the genetic variability of the plants in cultivation.

Tips

1. Treat the seeds with a fungicide which controls damping off (botrytis and rhizocotnia spp. etc) when they first germinate. This has been shown to drastically reduce damping off, the main killer of Nepenthes seedlings. Further applications every month can be beneficial. When they get a bit older, a systemic fungicide can be beneficial as well (those containing thiophanate-methyl are safe for Nepenthes).

2. Be VERY strict with the temperature requirements - seeds from most lowland species will only germinate and survive at high percentages if kept constantly warm (i.e above 28C, but around 32C better), those from highland species are even more touchy, as day temps must be kept down, and night temps absolutely must drop below 17C for seedlings of most species to survive. Newly germinated seed is much more finicky about temperature than older plants.

3. Use very pure water, RO preferred.

4. Use an acidic medium - it varies between species, but a pH of around 5 is good.

5. For an excellent article on growing certain highland species from seed, go to a great article on the ICPS website.