That argument with a guy at the plant swap still bugs me

I was at the community garden swap in Austin last Saturday, trading some mint cuttings. This older guy started going off about how you should never compost nightshade plants because the toxins stick around. I told him I've been composting tomato vines for 5 years with no issues, and he just shook his head and walked away. Who's right here? Has anyone actually tested this or is it just an old wives tale?

3 comments

3 Comments

clark.alex25d ago

The older guy was wrong about nightshade toxins in compost. Those compounds break down during the composting process, especially in a hot pile that hits 130 degrees or more. I've composted tomato plants, potato vines, and pepper plants for years without any problems in my garden beds. The real risk is if you try to compost diseased plants, but even then the heat usually kills the pathogens.

mila_murphy2125d ago

The 130 degree rule only works if you're actually running a hot pile, which most home composters don't maintain consistently. I've been composting for over a decade and my pile rarely hits 130 for more than a day or two. Nightshade alkaloids like solanine are actually pretty stable and can survive in cooler compost. There was a study out of Oregon State that found tomato plant residues still had trace amounts of solanine after six months in a cold pile. I'm not saying you'll poison your garden, but I've seen potatoes sprout in my compost and those green sprouts are pure solanine. Better safe than sorry, so I just toss my nightshade vines in the municipal yard waste bin now.

the_christopher25d ago

Threw a whole bag of sprouted potatoes in my pile once and had little potato plants popping up all over my flower bed the next spring.