I was told not to compost tomato plants for some reason — I can’t remember why. Are they OK for vermicompost?
The only reason we don’t compost tomato plants is if they’re diseased, especially if they’re infected with late blight, which is fatal. The problem is easy to identify because every part of the plant is affected, fruit included. The stems often show signs of blight first — they turn black at the top — and then the fruit and foliage follow. Luckily, late blight isn’t as prevalent as early fungal issues, such as Septoria leaf spot and early blight, which slow down plants but rarely kill them. Both of these diseases are soilborne, and they turn the leaves yellow and spotted, starting at the bottom of the plant and then working their way upwards.
A plant with late blight should not be composted. The disease can overwinter in a compost pile or in a vermicomposting (worm composting) system. I wouldn’t want to compost diseased plants for fear of perpetuating the problem.
If plants are healthy at the end of the season, they can be safely composted or used for vermicomposting.
For more advice from Doug Oster, see:
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Doug Oster is the home and garden editor at the Pittsburgh Tribune-Review and is co-host of The Organic Gardeners on KDKA radio. Doug’s book Tomatoes Garlic Basil contains even more useful information.