Is it okay to put diseased plants in my compost pile?
That depends. There are two styles of composting: hot and cold. A hot compost pile is one that's carefully maintained so that it achieves optimal levels of air, moisture and heat. These piles can easily reach internal temperatures of 50 to 65°C, which are high enough to kill most weed seeds and pathogens. So if you're hot composting – and that’s a big "if" - then you have nothing to fear from diseased plant material.
The reason I say "if" is because hot composting is a bit problematic. No matter how hard most of us try, we can’t quite exercise the discipline necessary to achieve those optimal levels. As a result, most of us end up cold composting whether that was our initial intent or not.
Let’s face it, it’s just easier.
To hot compost, you'll need to keep your pile evenly moist, but not wet. You'll also need to add one part green, nitrogen-rich materials for every two parts brown, carbon-rich materials and turn your pile at least once a week. All of this will be for naught unless your compost pile is large enough to hold heat (approximately one cubic yard). If you get all this right, you’ll still have challenges keeping your compost pile hot through the winter months.
Most home gardeners cold compost by default. This method can result in temperatures high enough to melt any snow that lands on the pile, but too low to kill most weed seeds or pathogens. This is most likely your situation, so add diseased material with caution.
This is yet another case of do as I say and not as I do. (You’ll find there are a staggering number of these.) I routinely throw diseased plant material into my compost pile even though I don’t maintain it diligently enough to qualify as a hot compost pile. I have yet to run into any significant problems, but I'm tempting fate and will one day pay the price for it when some nasty disease takes out my garden. Somehow knowing that doesn't alter my habits.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
