Hi ,

It is OK to compost plant material from your garden for any plants that you are sure is disease free and you are hot composting .    "Hot composting," where compost pile temperatures rise significantly due to aerobic (oxygen-rich) microbe decay, is ideal, since that helps to kill pathogens (plus pests and weed seeds) that might be in the plant debris. Cold composting, does not reach or maintain hot enough temperatures for a particular length of time (which is needed to kill most pathogen spores, plus most weed seeds and pests), it's safest to not put any diseased plant material into the pile. Since this is the type of composting most gardeners use, as it requires less monitoring and intervention, that's why the best-practices for composting has become avoiding the addition of anything diseased to the pile. This is because it's more likely the spores in infected tissues will survive the composting process. While some plant diseases are somewhat host-specific and cannot infect just any plant they find themselves near, many are not that limited, where spreading finished compost contaminated with their spores risks causing new infections. Examples include many leaf spot diseases, Southern Blight and other blights, and root/crown/fruit rots. Cold compost piles don’t reach or sustain the high temperatures needed to kill pathogens. Fungi, bacteria, and viruses can survive in cooler, slower composting systems and may spread to healthy plants when the compost is used.

Here is what you should avoid putting into cold compost: Invasive plants or weeds with viable seeds; pet feces, large, untreated wood or branches – While small woody pieces can be added, large logs or untreated lumber may take years to break down and can harbor pests or pathogens; chemically treated yard waste – Items treated with pesticides, herbicides, or fertilizers can leach into the compost and harm plants; Meat, dairy, and oily foods – These can attract pests and create odors; cold composting is not designed to handle these; Sawdust from treated lumber – May contain chemicals and can be too carbon‑rich, slowing decomposition; Materials with high boron content – If soil tests show high boron, avoid using corrugated cardboard or certain sawdust types, as boron can accumulate in plants.

Cold composting is a slow process and can be successful but avoid adding any contaminated or diseased plants. When in doubt leave it out.

Hope this is helpful.

Christine