Mint Alleleopathy to Vegetable Seedlings.

[Peterparch]

I am finding that using my compost in a potting soil mix has had a negative effect on the germination of seedlings. Also, when used as a top dressing, the compost has a stunting effect on plant growth and produced a proliferation of catnip weeds.
The compost consists mostly of rotted (but not pasteurized) horse manure given to me by a friend who has horses.
I suspect that wild mint may have been growing in the manure before I got it and contaminated it with seeds and toxic compounds.
I have read that compounds produced by the mint family have a strong alleleopathic effect on plants grown in soil where mint had previously been grown. Has any one else experienced a similar problem or verify that my suspicions are valid?

 

[Meadowlark]

Your suspicions are correct. Mints including Cat Mint, Nepeta cataria, and Corean Mint, Agastache rugosa, are allopathic. My experience matches yours as it hits the seedlings especially hard.

 

[Peterparch]

Thank you for the confirmation! I guess that I will spread the rest of the compost under my fruit trees for weed control.

 

[Ruderunner]

I'm going out on a limb here and I'm guessing it depends on what you're planting. I had mint growing in the corners of our small plot and didn't seem to have much problem with it.

Peas, carrots, green beans, spinach all seemed to get along with it just fine. Especially the spinach.

Due to the recent engagement of that plot, I've removed most of the mint. Still some stragglers showing up. Also I did keep it contained, well pulled out what was reaching from the corners. Usually tossed it in the yard then ran it over with the mower. The clippings would dry a few days and get spread around the garden.