Sphag is a potentially tough potting medium, and one in which the quality (species) makes a huge difference! The 5-star NZ stuff is by far the best, being nice and fluffy, and staying that way for a fairly long time.
I find that mising something "springier" with it helps - I usually use coconut husk fiber.
Otherwise, you have to go one of two ways: pack it loosely when repotting, water it normally, but keep an eye on it for compression, or pack it fairly firmly, and then just barely moisten it when you water, so it won't compact any further.
Interestingly enough, if you have species that a very slim in their nutritional needs, that is, they can handle a lot of pure water only, sphagnum will grow from spores, and living sphagnum stays naturally airy.
|