invasives in town compost collection

Asked September 13, 2020, 8:25 PM EDT

There are many plants I keep out of my own compost because it doesn't get hot enough to render them safe. But what are things I should keep out of the yard waste our town (Mt Rainier) collects? (I'm thinking about plants with seeds, tubers, etc. that can propagate from the yard waste; also, dodder.) Can I rely on the heat of the big composting operations to make things safe? (The only thing the town asks that we keep out are poison ivy and similar plants, for the protection of the collectors.)

Prince George's County Maryland

1 Response

Composing operations in municipalities probably follow the U.S. Composting Council's guidelines regarding pile temperature, turning, aging time, etc. This helps to ensure weed seeds, pathogens, and pests are killed; tubers and rhizomes should also degrade. You could contact the facility used (or ask representatives from Mt. Rainier) about what types of plant waste are accepted (poison ivy aside) and how they manage their operation to ensure they aren't contributing to the spread of invasive plants when finished compost is distributed. (For example, finished compost can be re-colonized by blown-in weed seeds if not covered.)

Worst-case, if you aren't given reassuring information or if you aren't certain about their practices, you can always bag and dispose of (trash/landfill) invasive plant parts, rather than composting them.

Sidebar with regards to Dodder - all seven of the species recorded in Maryland (according to Maryland Biodiversity Project) are native. Two additional species are listed as non-native to MD (one is a U.S. native, the other introduced), but neither has any observations recorded and may not be present in the state at a meaningful level.