I put in my first couple beds this fall and wanted to put out a few seeds in some of the bigger gaps still remaining. Some of the seeds I have require a cold treatment so I thought I would use those. However, I have used mini bark mulch in all my beds because the nursery people told me that would be a good idea. I see that most of these seeds need to be on the surface or barely under the soil and I'm stumped on what to do now. Should I put them under the 2in of mulch I have or toss them on top of the mulch or maybe just pull the mulch back in those areas and leave it off over the winter.
Along the same lines, a lot of my new perennials are starting to seed and I was hoping they would sort of do some self seeding and fill in the areas (I left lots of space for them to do so). But will they do that now that I've mulched everything?
I know about winter sowing, and plan to do a small amount, but I have very little space for it and I plan to use that space for tomatoes and beans and a few early blooming flowers. So most of my flowers need to go out now (in the fall) or in the spring.
I've notice a lot of people here actually mulch with leaves, perhaps that would be a better plan in the future.
I think you'll need to push the mulch back from the area you want to seed. One of the benefits of mulch is that it helps keep weed seeds from germinating--ones that are underneath the mulch don't have enough light to germinate, and ones that fall on top of it don't have soil to stick their little roots into it. It doesn't 100% stop germination, but it certainly slows it down, so for your seeds to have the best chance I think you'll need to un-mulch the area. Then once the seedlings have germinated and gotten big enough, you can put mulch back around them again. For your reseeding plants, if they're things that reseed very readily you'll probably find that some are able to get their roots down through the mulch and into the soil (just like some weeds will still find a way to sprout even in mulched beds). But you won't get as many seedlings as if they could fall directly on the soil. But there's probably no point in moving the mulch now if the seeds have already fallen, otherwise you could just be sweeping away your seeds along with the mulch, so I'd just leave them alone and see what happens.
I would say the same thing whether you had bark mulch or leaves or any other sort of mulch. (The real advantage of using leaves for mulch is that they're free)
ecrane is right. I've been letting my flowers self-seed right on top of the mulch and they always give me plenty of volunteers. Actually, I get enough on most of them to share with family and friends. My black-eyed Susan, purple coneflowers, blanket flowers, Stokes astor, butterfly weed, and Shasta daisies are especially easy with the self-seeding. I think the nice thing is that I don't get overwhelmed with too many volunteers at one time. I've been leaving some where they are to help fill in gaps and moving some to other areas. I'm at a point where I almost have enough so I deadhead all but three or four seed heads. This fall I'm trying to increase my dwarf Joe Pye weed so I'm putting some seed under the mulch and just spreading some on top and watering it in--I'll see if there's any difference in germination numbers.