I don't know what that specific herbicide is, but yes, it probably would. IF it works similar to the active ingredient in Preen brand pre-emergent for gardens, it will stop seedlings from growing by "burning" (inhibiting the growth, I don't know the exact mechanism) roots, but won't affect the growth of larger plants once they get past the 4 to 6 leaf stage (as a rule, there are always exceptions).

With Preen, what it boils down to is that you can't direct-sow anything into treated soil. Your options then become 1) transplants, and most crops except for root crops can be done from transplants; or 2) create "clean zones" of untreated fresh soil of sufficient size to accommodate the seeds you wish to sow -- for example, if I wanted to direct sow a crop like carrots into a treated garden, I would probably excavate a trench about 8 inches wide and 6 inches deep, backfill with clean, high quality media such as ProMix or Miracle Grow, and plant the seeds into this, keeping them an inch or two away from each side. By the time the carrots grow large enough to expand their roots out of the clean soil, they will no longer be susceptible to the herbicide.

However, before doing either of these, you should do some research online into the specific active ingredient you used and see what effect it could have on seeding. It may be different from Preen.

What does the label say?

Pre-emergents affect ALL seeds, but it only affects them as seeds. Once they sprout, it no longer should have any effect.

Mix 3/4 of your compost with the existing soil and level it. Then, just to be safe, fill the rest of the bed with a mix of some of your compost and soil from non-treated soil. What you're aiming for is a 'safe zone' for your seeds, where they won't come in contact with the herbicide until after they sprout.

Next time, why not just lay some cardboard over the grass and pin it down with your garden box, and let the lack of light kill off the grass? Do this in fall, and fill the box with leaves and grass clippings. By spring, rake off anything the soil creatures haven't eaten and dragged underground, and you'll have a nice bed, ready to plant, and it won't have all the 'seasonings' of the toxins of this chemical soup.

Adding chemicals to good compost seems kind of contradictory, IMO. One of the big advantages of home gardening is knowing what's in your fruits and veggies, and what IS NOT in your fruits and veggies, esp if you are feeding children, elderly or people with compromised immune systems.

I looked up the MSDS (Material Safety & Data Sheet) for this product, and when I see a warning like the next paragrah (for Dithiopyr, the active ingredient), I do tend to wonder about the accumulative effects:

Ingestion: Call a physician or poison control center. Give person 1 to 2 glasses of water to drink, and induce vomiting by touching the back of throat with finger. If Syrup of Ipecac is available, give 1 tablespoon (15ml) followed by 1 to 2 glasses of water. If vomiting does not occur within 20 minutes, repeat dosage once. Never induce vomiting or give anything by mouth to an unconscious or convulsing person. Note to physician: no specific antidote is available. Treat symptomatically.

The other ingredients aren't any better:

Heavy aromatic naphtha
Naphthalene
1,2,4-Trimethylbenzene
1,3,5-Trimethylbenzene
2-Ethylhexanol

Many people argue that all these chemicals break down in the soil. Yes, they can, IF the soil is biologically active, and IF they aren't over-applied, which is usually not the case, which is why they show up in your drinking water.

Okay, rant over.

Sue