Propagation By Seeds
Propagating Nepenthes by seeds is usually done for one reason, to create hybrids. Otherwise, most Nepenthes cut rather easily, which can produce a mature plant much more quickly. It can take a few years to get a decent sized Nepenthes plant produced from seed.
Some Nepenthes species are not easy to take cuttings from. But with tissue culture available, most growers do not propagate species from seed. They can either take cuttings or grow small TC plants to sellable size.
But crossing different plants in order to create hybrids is an exciting reason to propagate from seed. Hybrids are only now really coming into their own as far as the end purchaser. Growers have always known how desirable hybrids were, but the end buyer is clueless without pictures to back them up. Its only recently that with many of the available hybrids having their pictures published on the web has demand begun to skyrocket for the hybrids. And given the different shapes, sizes, colors, etc of different species and forms, there is an endless number of new and unique crosses that can be made.
So, how do we go about creating Nepenthes seed? Nepenthes are unisex plants. This means that the flowers on a plant do not contain both male and female sex organs, as most flowering plants do. Each Nepenthes plant is either male or female.
In order to get seed, you have to have both a male and female Nepenthes in flower at the same time. Not easy to accomplish if you only have a few plants.
Growing true species from seed can be an even bigger challenge, as you have to have both a male and female of the particular species. The best thing you can do is to record on the plant's label the sex when it flowers, so that you can keep up with which sex you need. Then, your best option is likely to trade for the opposite sexed species from another grower who knows the sex of their plant. It's always a good idea to record the sex of a plant when it flowers, as if you ever take cuttings of the plant, you can sell or trade the plant with info on the sex.
The beauty about a female Nepenthes flower stalk is that it can contain dozens to hundreds of individual female flowers, each which can be individually crossed with different plants. You can cross one flower on the plant with another plant of the same species, another flower with a different species altogether, and so on. One female flower stalk can have all kinds of different crosses made with it. But you must label each flower so that you can identify the seed that comes from it, unless you are crossing every flower with a single other male plant. (Very small colored thread tied around each small female flower can work.)
Nepenthes seed look like long brown filament whiskers when mature. The female pod opens up, revealing the seed. You'll want to watch for when the pods begin to open, and then remove the seeds and plant them immediately. The pods will mature from the base of the stalk towards the top, just like the flowers matured in sequence.
Nepenthes seeds are not usually viable for very long. (This means they do not germinate at a high rate the longer you wait to sow them.) Nepenthes seed can not be stored for long periods of time, and dont take well to the freezer. (Which is how most plant seeds can be stored for a very long time.) However, the germination rate can be very high if they are sown immediately.
Once you harvest the seed, you'll want to plant them as soon as possible. I find that ground up sphagnum works very well as an initial starting seed medium. Long fiber itself should not be used unless the seedlings will grow on in their germination spot for a year or more. It can be very difficult to pluck Nepenthes seedlings out of long fiber, as the fiber in the moss can interconnect and disturb the other seedlings. You attempt to remove one seedling, and the moss fibers ends up disturbing or breaking the roots of several others.
I normally place ground up sphagnum in some sort of seedling tray, and sprinkle the seeds on top of this. Wetting the soil one final time before planting the seed aids in getting the seed to sit in contact with the soil, which helps with germination. Do not cover the seeds. I place the seed trays right along side the mother plants in the same environment in the greenhouse.
If you are growing your nepenthes in an outdoor greenhouse, you likely will have to do nothing other than place the seed into a good moist medium for them to germinate. If you are attempting to germinate lowland seedlings in a greenhouse in the middle of winter, it may help if bottom heat is applied to the soil. I've never had to this, as seed which is immediately sown germinates within a few days to a few weeks without fail, at a high germination rate. But if the soil temp is somewhat cold at night, use of a propagation/soil heater, which can provide bottom heat, may help aid germination.
My nepenthes plants in the greenhouse have no problems getting themselves fertilized, whether I do it, or something else does. Because I normally line the benches with a layer of moist sphagnum moss, the seeds which fall from the plants in which I dont harvest often germinate around the female parent in the bench soil right underneath the motherplant.
Due to the thin whisker shape of the seeds, each female flower can produce an abundance of seed. Considering some plants can have 100 female flowers or more, a large female Nepenthes can produce a large amount of seed. Undoubtedly, a female will produce many more seeds than an individual would normally care about sowing themselves, so finding other seed trading partners is a good idea. Each of you can trade off different species and hybrid species. Sending seeds through the mail within a few days of harvesting normally means a very high germination rate. They can be stored longer, but the germination rates will be lower. Given the over abundance of seeds, this isnt necessarily a terrible thing. Storing the seeds for more than a few months though will greatly reduce the number of seeds that germinate, so dont wait more than that amount of time before getting them started.