If you’re trying to build up a compost pile to fertilize your backyard garden, you might find yourself wondering how long different types of shells and peels take to decompose.
For pistachio shells, the answer is a little more involved than you might think.
While some things, like orange peels, decompose within six months or so, the process for hard nut shells like those on a pistachio can take three years in the average compost bin.
Compost bins are specifically designed to help things break down faster, so out in the wild, a pistachio shell might take even longer to decay.
If you think this means that you’re better off just throwing away pistachio shells rather than throwing them into the compost pile, that couldn’t be further from the truth.
Adding pistachio shells to your backyard compost pile is a great way to bulk up the pile and help keep your compost from getting too moist.
Just make sure to either use unsalted pistachio shells or wash the shells before adding them to the pile.
That way you don’t have to worry about too much salt getting into your garden’s soil.
Ways to Speed Up the Decomposition Process
Nutshells, like pistachio shells, take a very long time to decompose, but if you’re a little impatient and you don’t want to wait months or even years for your compost to become usable, there are fortunately a few ways to make the compost pile break down a little faster.
Crush the Shells Before Adding Them to the Compost Pile
Bigger objects are going to take longer to break down than smaller ones, so instead of throwing whole pistachio shells onto the pile, you can speed up the decomposition process by breaking them up first.
Unfortunately, pistachio shells are probably a little too tough to smash with just your hands, but there are a lot of other ways to get them into smaller pieces.
The quickest and safest option is to simply throw some pistachio shells into a food processor and pulse until they’re unrecognizable as shells.
You could also use a rolling pin and crush them inside a bag.
If you don’t have a food processor or a rolling pin, though, there are some creative (though questionably safe) ways to crush the shells.
One of these is to throw the bag onto your driveway and run it over with your car a few times.
You could also take a hammer, mallet, or any other heavy object with a flat surface that’s good for crushing things and spend some time smashing the shells with that.
If you’re going to use a hammer, though, make sure you’re being safe.
Wear goggles in case any shell fragments come flying up into your face, and be careful not to smash one of your fingers (or anything else).
Make Sure the Ratio of Nitrogen to Carbon is Right
Pistachio shells are great because they can help keep your compost from getting too moist.
If your compost is very sludgy or wet, it’s not going to break down as fast, so having some things to keep it a little drier is good.
They’re also rich in carbon, which is one of the chemicals microorganisms need to break down compost materials.
However, as with most things, it’s important not to put too much of one thing into your compost bin.
Shells help dry it out and add carbon, but a compost bin that’s too dry or too carbon-heavy also won’t decompose very quickly.
“Green” ingredients like grass clippings can make your compost pile wetter, but they also add nitrogen, the other ingredient microorganisms need to break down materials.
Essentially, you shouldn’t have a compost bin that’s all green ingredients, but neither should you have one that’s all nuts and twigs or “brown” ingredients.
You need a good amount of both to ensure your compost breaks down as fast as it can.
Heat the Compost Up
Bacteria are more active when it’s warmer, so in addition to making sure your ingredients are finely chopped when they go into the pile and having a healthy mixture of nitrogen-rich and carbon-rich materials.
You might also want to encourage increased activity by creating what’s called a hot compost.
To do that, you’re going to need to find a way to warm the compost up and then make sure that it stays warm.
For the first step, you can stick a hot water bottle (or several, depending on how big your compost pile is) right into the heap.
Unfortunately, that’s not going to keep the compost hot enough for long enough for there to be any real effects.
If you want the compost to stay hot, you’ll need to keep it insulated.
If you have your compost in an insulated bin, that’ll keep the temperature higher for longer. You can also use what’s called a compost duvet to stop the pile from cooling down too fast.
Compost duvets aren’t hard to make if you don’t want to go out and buy one. Essentially they’re just something that you put over the top of the compost bin to keep the heat in.
You can do that with some bubble wrap, plastic, an old blanket you don’t care about, or anything, really, as long as it will trap the heat.
Composting with Pistachios
Going back to the original question, “how long does it take pistachio shells to decompose?” the answer is, normally, three years or even longer.
As we’ve seen, though, there are ways to speed up that process so you can use your compost sooner.
Keep in mind that even with these techniques, it may still take a long time for the more stubborn materials in your compost bin to break down completely.
Stay patient and before long, you’ll have a great fertilizer for your garden.