Yep, although it depends on the mulch. I just pull back the mulch with a rake (because sometimes I have snakes in my mulch) and sow the seeds. I don't pull the mulch back up around the newly emerged plants until they are a couple of inches tall and I still make sure it is about 1/8 tp 1/4" away from the stem. Lots of sow bugs and pill bugs tend to reside in my mulch and they love to eat tender young seedlings, especially when the weather is hot and dry. To thwart them, I keep the mulch pulled back from the seedlings. Sometimes they still like to chomp on the seedlings. If they do, I scatter either Slug-Go or Slug-Go Plus (I always have one of these two organic products in my potting shed precisely because of the pill bugs and sow bugs) around the young seedlings. If I have run out of Slug-Go Plus, I'll scatter an organic fire ant product containing spinosad along with the regular Slug-Go. The difference between Slug-Go and Slug-Go Plus is that the Plus also contains spinosad. I don't have slugs, but the pill bugs and sow bugs respond well to Slug-Go and Slug-Go Plus. After a period of heavy rainfall, the pill bug and sow bug population in my mulched beds explodes and they eat everything in sight, including plants and fruit, including tomatoes. That is the biggest downside to mulching. I wish the pill bugs and sow bugs, which are generally decomposers who break down organic matter would confine themselves to eating only organic matter on the soil or in the soil, but in our generally hot and dry climate they really attack living plants and fruit too.

I was afraid of that. Was just hoping that they would somehow come up if i threw them on top of the mulch. Seems to still work with weed and grass seeds! Just ordered cosmos, zinnias and laura bush petunias (thanks to your info). I spend too much time and money on my flower beds. I love them but they are a definite job. I am still planting and pulling. My pentas just did not do well this spring even planting them late. Too much cool and rain I guess. So have to replace some of them with something else.Think I may just sow some seeds and see what happens.Oh and I ordered larkspur after seeing them in a post. Guess I sow them late fall? Thanks

Well, they could come up. That's why I said it depends on the mulch. I can broadcast sow into a fine shredded bark mulch, for example, and get reasonably good results, but if a bed has a chunkier bark mulch, the seeds often wash underneath the big chunks which can keep them from sprouting...or from making it out from under the big chunks after they sprout.

You can sow larkspur any time from fall (after the first killing freeze) through spring. I tend to sow the seed in December or January, often have sprouts by late January and flowers in March, or in April of a cooler year. Mine reseed every year, so I only sow new ones if I have disturbed the soil and am concerned that not enough of the self-sown seed might sprout because disturbing the soil might have buried them too deeply in the soil. Or, I sow seed if I want a new color or if I want them in a new place.

In the winter of 2011-2012 I broadcast sowed a lot of larkspur in the front meadow, between my garden and the roadway, and didn't get many. I likely sowed too late. This year, though, there are larkspur plants scattered across the meadow so they did sprout, but they sprouted a year later than I expected.

Laura Bush petunia is incredible. My garden is full of it since it readily self sows. You have to cut it back hard once or twice a summer but then it regrows fast and blooms its head off. In my garden, I usually have LB petunias in bloom from March or April through at least November, and often December. They are both very heat-tolerant and also somewhat cold-tolerant.

Before I started growing LB petunias, I grew one in Texas called VIP (Very Important Petunia) and then Laura Bush and got hooked. They are the only petunias I've ever grown that look as good in August as they did in May, but only if I have cut them back hard in late June or early July to stimulate a new flush of vegetative growth and blooming.