I have heard that I need to plant periniilal seed sin the fall so that they will come up in the SPring. In the past, I have always planted seeds in the spring. Thoughts?

rc-
It may depend on what it is you're growing. I have 4 o'clocks that reseed along w/hollyhocks. That tells me those should be planted in the fall when they drop & seed themselves. I bet Dragonfly. or Saccharum will know for sure & respond if they read this.
Patty

Yep, pjva is right on. It depends on the species; in nature, some plants drop their seeds late in the season, and in many cases the seeds actually require a cold period before they are able to germinate in the spring. Other plants develop and drop their seeds in the spring or summer and can immediately germinate and start growing.

You can simulate the winter cooling for those plants that require it by placing the seeds into a refrigerator for several weeks before planting in the spring; this is a type of "stratification."

I Winter sow perennial seeds because I will usually get flowers the first season that way (many perennials won't flower the first year). I have also Fall-sown perennials in pots and kept sheltered until Spring for transplanting. Either way works well. If you want to direct sow in Fall, do it early enough for the plants to become established somewhat. Otherwise, some species will have difficulty surviving Winter with shallow roots.

rc-
(see, told ya-'Sacch' & 'Dragon' know everything!) Would probably help if we knew what you were wanting to grow. W/4 o'clocks they don't drop seeds til it frosts, the plants diedown & I guess actually mulch the seeds. I don't do a darn thing-except maybe pick off some seeds to put out somewhere else & strangely enough, plant 'em in the spring!! & that has worked too. If you are putting in plants instead, I'd do it now.
Patty