I have pots of chrysanthemums and geraniums that were killed by the frost. If I put them in the compost are they likely to sprout seedlings when I put the compost in my garden later?
Unless they succumbed to some kind of disease, frost-killed plants such as the mums, along with other end-of-the-season garden debris, are a good addition to compost, so toss them in and don’t worry about it. If they are completely dead, they are not likely to re-sprout, say compost experts. If, however, the plants you toss in have mature seeds, the seeds may sprout if the compost doesn’t get hot enough.
Here’s a quick lesson on hot vs. cold compost: The best compost is made with a ratio of nitrogen-rich “green” material such as fruit and vegetable scraps, fresh grass clippings, green yard waste and so forth, and carbon-rich “brown” materials such as dry leaves, straw, soil, woody material and even newspaper and paper towel tubes. The ideal carbon-to-nitrogen ratio is 30:1. A well-working pile will heat up to about 130 – 150 degrees F. (you can buy a compost thermometer that allows you to check the temperature). A pile that heats up to at least 130 degrees F will kill mature seeds of weeds and other plants that you put in there.
That may take more tending and precise calculation than an average gardener wants to do, though, so it’s more likely you’ll end up with a “cold” pile, which still makes compost, but more slowly – over the course of a few months instead of a few weeks. But again, if what you put in is completely dead, it will just rot and not sprout again.
Metro Nashville’s Public Works Department provides a booklet called “The Dirt on Composting” with simple guidelines to composting food and yard waste. Check it out here.