I buy expensive compost every year for my greenhouse and pots. I then spread the used compost on my garden. I now have a garden full of a new weed and noticed one growing from a tear in an unused bag of compost. Can manufactured compost contain weed seeds?

Potting compost is made of stuff that inherently comes with weed seeds: forest products, manure, compost... . If the soil is pasteurized before being bagged, it shouldn't contain many viable seeds but it seems there's always a few.

Or it could have been a drifting weed seed that lodged in a rip in the bag. Some are remarkable at transporting themselves.

If - somehow for the sake of argument - you do find yourself with a bag of supposedly weed-free compost or potting medium, can you bake it @450*F for an hour to kill any weed seeds? if not, then might any other ideas possibly apply?

You can bake soil to kill weed seeds but a soil temperature of 180F is enough. Higher than that, you kill all the soil bacteria too.

Of course, when you do that, your neighbors and significant other might not appreciate the aroma. So I've heard.

I've pasteurized soil in my oven. I filled a pyrex dish with wet potting soil, covered it with foil and baked it to 180F. The smell was very earthy but not terrible.

Lucy - thank you - Your information simplifies my approach to certain garden issues.

Cal - Somehow my curiosity has put me on the wrong side of a 'politically correct' neighborhood issue and it seems that certain people might be expected to 'give me space.' Sooooo - your response is inspiring me to raise a gentle stink that might be neither terrible nor obvious. Thank you.

You go, Girl!