Composting Potato Haulms (Tops): Weighing the Risks and Benefits

“Haulms” are potato stems and foliage. Composting them is debated: they decompose like any organic matter, but potatoes (nightshades) contain alkaloids that may persist, and haulms often carry blight spores. Tiny tubers left on stems can sprout in the warm pile.

Best Practices If You Compost Haulms

• Only compost disease-free haulms.
• Remove all small tubers to avoid volunteers.
• Run a hot pile (130°F+ for several days) to deactivate alkaloids and kill pathogens.
• Don’t use resulting compost on other nightshades (tomatoes, peppers, eggplant) if unsure.

If concerned, “when in doubt, throw it out.” Many gardeners compost all organic matter but discard diseased plants.