Nurseries will declare plants "out of stock" if all they have are plants not of sellable size, not yet rooted, or only their stock plants (the mature "mother" plants they take cuttings or tissue samples from.)
Apollyon wrote:Perhaps nurseries up their stock of Nepenthes in spring just based off buying trends
That is, indeed, a common practice for any nursery -- no matter what type of plant they sell. It makes no sense to stock up on plants that won't sell well or have too low of a profit margin. Always a bit of a gamble. Choose poorly and a nursery may find it hard to stay afloat. If you stock up on a plant that "everybody
" is selling, you may have to practically "give the plant away" just to get rid of them.
TrapsAndDews wrote:How do they do that? Doesn't it take time to propagate plants?
It certainly does. As Apollyon mentioned, "Nurseries will probably take cuttings around the beginning of fall to have plants by the time spring picks up in March.
". Again, very common practice in any kind of nursery. Then too, keep in mind that many nurseries do not propagate the plants they sell. Some buy plugs/very young plants and grow them up to a sellable size (whatever they determine that to be). Some buy plants of sellable size cheaply in lots, then mark the plants up and flip them. Some do a combination of all of these strategies.
The type of plant can also make a difference. I know you said you were looking at neps, but if you had been considering sarrs, for example, you wouldn't likely find much available until spring as they are dormant right now. (And particularly folks who live in the colder zones won't be planting anything outside anytime soon.) I would imagine that this time of year would be a very bad time to ship heat loving plants like some of the petiolaris Drosera.