Can You Compost Nut Shells?
Yes. Peanut, pistachio, almond and pecan shells compost as a slow, carbon-rich brown, especially when crushed. Go easy on black walnut hulls and shells, which contain juglone, a compound tomatoes and some other plants are sensitive to.
At a glance
| Home compost pile | Yes |
|---|---|
| Green or brown | Brown (carbon-rich) |
| Moisture | Dry |
| Prep | Chop into small pieces |
| Worm bin | With care |
| Bokashi | With care |
How to compost nut shells
Crush shells with a rolling pin or in a bag underfoot to speed things up. Mix them through the pile a few handfuls at a time. Rinse heavily salted shells, like roasted peanuts or pistachios, or leave them out if you eat a lot.
Extension guides generally note that juglone breaks down with composting over time, so compost black walnut material separately and age it well before using it near tomatoes.
What goes wrong
Hard shells like pistachio and pecan can last a year or more. Sift them out and add them to the next batch, or use them as mulch. Large amounts of salted shells add more salt than you want in garden soil.
Worm bins and bokashi
Worm bin: Shells are too hard for worms to do much with; small amounts of crushed, unsalted shells just add grit.
Bokashi: Shells come out of bokashi mostly unchanged, so add them to the pile instead.
This counts as a brown. Adding a lot of it? Check the balance with the compost mix calculator.
From hopcompost.com/can-you-compost/nut-shells/ · General guidance, not professional advice.
Frequently asked questions
Can you compost peanut shells?
Yes. Crush them and rinse off heavy salt. They're a slow brown that adds structure to the pile.
Can you compost pistachio shells?
Yes, but they're very slow. Crush them, or expect to find them in finished compost and toss them back into the next batch.
Are walnut shells bad for compost?
Black walnut hulls and shells contain juglone, which some plants such as tomatoes react to. Small amounts in a well-aged pile are generally fine; large amounts are better composted separately and aged longer.