Help on soil for starting seeds

[markoboston]

I bought a house last year and built my first garden bed last month. I just dug up dirt and sod and built a raised bed by digging a trench around the bed and piling dirt inside the trenches. Then I dumped about 1 inch of stuff from a bag labeled "black mulch" on the bed and planted onion seeds in it. (This mulch seems to be partly decomposed landscaping waste including woody branches or twigs.) We had days and days and maybe 10 inches of rain over the next two weeks. Not a single onion has sprouted. Now I'm thinking I was wrong to put this black mulch on the bed. Do you think the bed will be okay if I scrape the mulch off? What do I need to put on the bed once I get the mulch off, if anything, to help seeds sprout?

A related question is what to put in planters that I want to use for germinating tomato and maybe eggplant seeds? Do I have to go out and buy seed-starting mix? Could I just use soil from my yard? Thanks in advance.

[rainbowgardener]

The black mulch is usually bark and wood chips. As such it is way too heavy and coarse for seeds to sprout into. It is meant to put down in beds of big plants to cover the soil between them. If you planted the seeds in the mulch, when you remove the mulch you will be removing the seeds too, so you will need to start over.

Yes actually for best results, you really need to get a bag of potting soil for starting seeds in. Even the seeds I start directly in the ground, I usually turn the soil and crumble it so it is fine, make a row, and then put a little layer of potting soil in the bottom of the row, just to give the seeds something that is soft and loose to root into. Once they are started they don't need extra help. One bag of potting soil goes a long ways and isn't that expensive. The garden soil tends to be heavier and denser and doesn't drain well enough for use in containers, especially for starting seeds.