Compost volunteer plants: Pull or keep?

July 22, 2020 1:16 AM

There are some potato plants popping up out of my compost heap, growing from kitchen scraps. I have no plans to try to grow any potatoes, so are these plants A) robbing nutrients from my compost heap, and I should pull them out quickly, or B) taking in more energy/nutrients from the sun and the air, enriching my future compost, and I should let them grow? Or some combination of the two?
posted by Glier's Goetta to Home & Garden (6 answers total)

Mainly B, pull out now b4 they make many little, nutritionally worthless potatoes that will produce more and more of the same. Also I would expect potatoes to rot in a bad way rather than take part in composting.
posted by unearthed at 1:38 AM on July 22, 2020

Best answer: I'd pull them out, compost the stems and leaves, and throw away any little potatoes that you find. The latter will just re-grow if your compost isn't getting hot enough to kill them off (and it probably isn't).
posted by pipeski at 4:05 AM on July 22, 2020 [1 favorite]

Best answer: Pull, so you’re less likely to end up harboring late blight.
posted by zamboni at 5:19 AM on July 22, 2020 [3 favorites]

If you are curious about estimating the real ratios: Around 80% of the mass of a potato is water. About half the dry biomass of plants is carbon, and the vast majority of that is from the atmosphere. (Here’s a fun freely accessible article from Nature, 1877).

So out of a kg potatoes, 800g is water, 100g is carbon, and a max of 100g is coming from your compost (these figures are for the tubers, the greens will have even more water).

I’d personally let them go and eat any that looked good in the fall, and put the rest on the curb with a ‘free seed potatoes’ sign.
posted by SaltySalticid at 5:27 AM on July 22, 2020 [1 favorite]

Best answer: With a few exceptions (like the pea family) plants don't take in nutrients from the sun and air. They take in and store energy that way, which will not be available to future plants. They take nutrients from the soil. Potatoes are notorious for taking a lot of nutrients from the soil. Pull them out.
posted by agentofselection at 8:54 AM on July 22, 2020 [1 favorite]

Response by poster: Thank you, everyone! I will pull those suckers out and hopefully prevent an endless potato cycle happening in my compost.
posted by Glier's Goetta at 1:33 AM on July 23, 2020