valleylynn said:June, when allowing the plants to self seed, which ones germinate before winter, and which lay over the winter in seed form, then germinate sometime in the spring?
Valleylynn, the answer depends on how long it takes the seed to ripen and fall, and on what factors are needed to stimulate germination in that particular species. With thousands of alpine species that can be grown, it's impossible to give a comprehensive answer but this is probably a decent general guideline.... Species with simple germination - that require only moisture and warmth - will germinate at any time when enough moisture is present and it's warm enough. Species whose seeds require stratification (a cold period, or alternating periods of cold and warmth) will, generally speaking, be more likely to germinate in spring.
Any plant that's capable of producing viable seed will self-seed in the right conditions.
The most prominent self-seeders in my rock gardens - surprisingly few, really (the tufa beds are still fairly recent and it takes time) - are not problematic (I'd turf ones that were, or move them out into regular soil where there would be more competition). A few that spring to mind:
Campanula hawkinsiana is monocarpic so I'm very pleased that it self-seeds:
Saponaria pumilio gently self-seeds around itself:
Lupinus caespitosus var. utahensis - good thing it does self-seed because I'm still looking for the trick to finding conditions where a plant will live more than two years:
Dianthus glacialis seeds a little around itself:
Campanula saxifraga blooms very heavily and long and so produces quite a bit of seed - a little weeding is necessary now after many years:
Hypericum aviculariifolium ssp. uniflorum - another one that so far has been monocarpic for me, although I think it should be perennial:
Campanula thyrsoides is an alpine meadow plant but it's not in my rock gardens (too big); it self-seeds reliably - also good because it's monocarpic:
