Pistachio shells in compost

I can throw my peel on the ground, right?

by Jana Hemphill
When you’re packing snacks or a lunch to eat during a walk or hike, what do you bring? Do you think about bringing a banana, orange, or pistachios, since their peels and shells are biodegradable? After all, they’re natural, right? Just how long does it take for these things to decompose? Let’s take a look!
A banana peel slowly decomposing in my backyard. Photo: Jana Hemphill.Banana peels: The peels of bananas take up to 2 years to biodegrade. My first-hand experience shows this to be true so far—a banana peel that my husband left in our backyard on the way to a mountain bike ride last fall has blackened and shrunk (except for the stem!), but it still remains a dry banana peel in our backyard. It’s been around 7 months so far and none of the critters that have eaten my garden kale or fallen millet from the bird feeder have shown an interest in the banana peel.
Orange peels: It is estimated that orange peels take around 6 months to decompose, although in drier environments like Central Oregon, oranges can last indefinitely. It’s interesting to note that orange peels contain a natural insecticide, keeping it safe from insects nibbling on it. (Have you ever thought about how more “natural” insecticides usually have some type of citrus oil in them?)
Pistachio shells: Pistachio shells decompose slowly and can take several years to biodegrade completely in a compost pile. Since compost piles offer more ideal conditions to decompose than a natural environment, it is likely pistachio shells will take even longer than 3 years to biodegrade in the outdoors.
Other items: While outdoors, there are several other items that are often left behind. Toilet paper can take 5 weeks or more to biodegrade, depending on whether it’s been buried or not. Kleenex would theoretically take a little longer, if using ones that are thicker than toilet paper. Wet wipes take around 100 years to decompose. Dog poop bags biodegrade in around 10-20 years. Overall, it seems things take a long time!
Orange peels left on the side of the trail. Photo: Land Trust.Why does it matter?
There are several reasons why it’s better to not throw your organic litter on the ground when you’re outside. One reason is for the benefit of wildlife. When wildlife (including squirrels, chipmunks, and birds) eat something that’s not typically in their diet, it often leads to future issues, including things like an inability to process large amounts of salt or winter starvation.
Another reason is for the benefit of other people enjoying the outdoors. There are people who enjoy the feeling of solitude and “being in nature” that can exist while being outside. Seeing human litter on the trail (in any form) can remove that feeling. And I’ve never met someone who enjoys finding used toilet paper! Not leaving organic litter while outdoors is respectful of others’ experiences.
Along the same line, please be respectful if you want to educate someone about decomposing litter. Lecturing is typically not the most respectful or successful way to talk to others enjoying the outdoors. Also, keep in mind that not everyone has had the privilege to experience the outdoors from a young age and gotten the opportunity to learn about things like biodegradable litter (we’re all continuing to learn, after all!).
What should I do then?
There are a few options. Certainly, continue to bring bananas, oranges, and pistachios with you when going outside. You can bring an extra plastic bag with you for trash, then dispose of it when you get back home. If you want extra credit, you can have a bag for organic trash that you put in your compost pile when you’re back home. You can also look at other snack options or buy pre-shelled pistachios. A good general rule of thumb is that if you bring something with you when outdoors, you should bring it back with you too.
One last note
Decomposition of items varies based on environmental factors like sun exposure, rainfall, elevation, etc. While I have tried to be as accurate as possible for Central Oregon, please keep in mind that things could take longer or shorter, depending on where they are left.
Thank you to the Deschutes Trail Coalition and the Access Fund for their assistance with decomposition times for this blog post.

Learn more:

  • Being Better Stewards for Land and Wildlife
  • Leave No Trace website
  • The Miseducation of Leave No Trace

Can Pistachio nut shells be added to the compost bin? – Knowledgebase Question

The answer like most things with compost is “it depends.” It depends on your setup, where your compost bin is, what you’re using the compost for, and how long you’re composting.
I generally agree with NGA that seedy weeds are about the only thing I DON’T put in my compost, but only because I don’t put time and work into creating well-mixed, frequently-turned, HOT compost.
With respect to break-down of nut shells, I don’t care. The surface of my garden is littered with pieces of composted eggshell, chicken and beef bones, and nut shells. It doesn’t hurt anything and finishes breaking down slowly over a period of years. I’m not trying to win an award for manicured garden.
With respect to salt, it depends on relative volume. A 1/2 gallon of salty pistachio shells (that’s a lot of shells) in a 64 cuft compost pile (4x4x4) is NOT a problem. A 50-lb sack of salty nuts…that might be a problem, but it might not be. When I have a bag of salty peanut shells from a restaurant, I usually use them as surface mulch around my asparagus, because asparagus doesn’t mind a little salt.
With respect to vermin and smells, it depends on where you are and what type of compost bin you have. If your compost bin is on an apartment balcony, you may need to be more conservative in what you put in the bin. I have a large plastic-walled bin with plastic and wire mesh on top. I have to use the mesh because of dogs and racoons. Now I compost raw meat, cooked meat, fat, oil, nut shells, eggshells, paper plates, napkins, qtips, paper towels, and the rest of the kitchen and garden waste. It helps to have a lot of carbonaceous material (the browns) to mix with the above materials since they’re high in water and nitrogen. Covering with lot of carbon material helps to eliminate flies, other bugs, smells, and 4-legged pests.
In warm climates or in the summer, you are likely to attract soldier flies if you compost kitchen scraps. I’m trying to make compost – not fat larvae. So in the summer, I usually bury my compost in wide trenches in an unused garden bed…covered with wire and plastic mesh to keep dogs from digging it up.
I leave compost in the bin for 6 – 12 months, and usually only turn it a few times. When I use my compost in the garden, I sometimes shake it through a homemade 1/2 inch mesh screening box. And then sometimes after picking out the occasional pieces of plastic and foil, I’ll just throw all the larger pieces onto the garden surface anyway or maybe back into the compost bin.
Hope this helps a bit. Keep on gardening!!

Pistachio shells

Some pistachio shells (and fruit) are dyed…also they contain a chemical called urushiol that can cause allergic reactions in some.
From Wikipedia:
Toxin and safety concerns
As with other tree seeds, aflatoxin is a toxin found in poorly harvested or processed pistachios. Aflatoxins are potent carcinogenic chemicals produced by molds such as Aspergillus flavus and Aspergillus parasiticus. The mold contamination may occur from soil, poor storage, and spread by pests. High levels of mold growth typically appear as gray to black filament-like growth. It is unsafe to eat mold-infected and aflatoxin-contaminated pistachios. Aflatoxin contamination is a frequent risk, particularly in warmer and humid environments. Food contaminated with aflatoxins has been found as the cause of frequent outbreaks of acute illnesses in parts of the world. In some cases, such as Kenya, this has led to several deaths.
Pistachio shells typically split naturally prior to harvest, with a hull covering the intact seeds. The hull protects the kernel from invasion by molds and insects. But this hull protection can be damaged in the orchard by poor orchard management practices, by birds, or after harvest, which makes it much easier for pistachios to be exposed to contamination. Some pistachios undergo so-called “early split,” wherein both the hull and the shell split. Damage or early splits can lead to aflatoxin contamination. In some cases, a harvest may be treated to keep contamination below strict food safety thresholds; in other cases, an entire batch of pistachios must be destroyed because of aflatoxin contamination. In September 1997, the European Union placed its first ban on pistachio imports from Iran due to high levels of aflatoxin. The ban was lifted in December 1997 after Iran introduced and improved food safety inspections and product quality.
Recycling the shells
Empty pistachio shells can be recycled in several ways. If unsalted, the shells need neither washing nor drying before reuse but washing is simple if this is not the case. Practical uses include as a fire starter, just as crumpled paper is used as kindling; to line the bottom of pots containing houseplants, for drainage and retention of soil for up to two years; as a mulch for shrubs and plants that require acid soils; as a medium for orchids; and as an addition to a compost pile designed for wood items that take longer to decompose than leafy materials, taking up to a year for pistachio shells to decompose unless soil is added to the mix. Shells from salted pistachios can also be placed around the base of plants to deter slugs and snails. Craft uses for the shells include Christmas tree ornaments, jewelry, mosaics, and rattles. Research indicates that pistachio shells may be helpful in cleaning up pollution created by mercury emissions.

Once you’ve enjoyed a fresh cracked Natchitoches pecan, you may be tempted to just toss your shells into the compost pile. However, like the pecan meats, pecan shells have a ton of great uses. Instead of simply tossing them, here are some unique ways to use those leftover shells.

Pecan Shells Are Great For Smoking

They are great for smoke flavoring meat on an outdoor grill or smoker. They burn easily and add a sweet flavor to your meat. To use your pecan shells for smoking, you will first need to clean them a bit and make sure they are completely dry. You can use them either as kindling along with some pecan wood to build a base layer of flavor or simply toss a handful in towards the end to add a boost of smoky sweetness.

Pecan Shells Can Be Used In Homemade Beauty Products

They also make a great material for exfoliation. The natural oils help nourish and moisturize the skin while the rough granules help remove any stubborn dirt or dead skin. Start by placing your pecan shells in a food processors or coffee grinder and grind them into your desired texture. Then add the grounds to your homemade soaps, body scrubs, or facial cleansers.

Pecan Shells Make Great Mulch

If you are looking for an attractive addition to your landscaping that also helps retain moisture in the soil, pecan shells are a great addition to your mulch. Simply break the shells into smaller pieces and use alone of mixed into your favorite mulch. They also help deter slugs who hate the sharp edges, so it’s a perfect mulch to place around any vulnerable plants in your garden.

Pecan Shells Make Adorable Children’s Crafts

If you are looking for a fun and free afternoon craft project with your kids, you can use pecan shells to make small animals. Simply take the shell halves, flip them over and paint them like any animal you want. You can also add googly eyes, small wings made with paper, or feet made with little beads or rocks. Use your imagination to build your own pecan shell animal zoo!

There are many uses for pecan shells, so the next time you are buying some delicious Natchitoches Pecans, consider getting a bag of pecans in shells. Not only will you enjoy the sweet flavor of the best pecans in the world, you can use the shells too!

The Basics of Pecan Shell Mulch

Why Mulch?

What about garden mulch drives countless gardeners to replace it year after year, regardless of the cost and labor involved? Mulch:

  • Reduces or eliminates weeds.
  • Slows soil moisture evaporation.
  • Slows soil moisture evaporation.
  • Protects soil from severe temperature fluctuations.
  • Protects perennials from winter cold.
  • Keeps splashing mud off plants and pots.
  • Forms a barrier between the soil and ground-sprawling crops.
  • Gives garden beds a professionally landscaped look.

Why Pecan Shell Mulch?

As organic mulch, pecan shells offer even more benefits than inorganic ones such as gravel:

  • In summer, they extend the life of heat-sensitive crops by cooling the soil.
  • When applied in fall before cold weather moves in, they extend the growing season.
  • They decompose much more slowly — and need replacing much less frequently — than wood chips or shredded bark.
  • By breaking down, they boost soil nutrients and improve soil texture. And because they acidifies the soil, the shells are a great mulch for rhododendrons, azaleas and other acid-loving plants.
  • The shells’ sharp edges are a great deterrent to snails, slugs and neighborhood cats who regard gardens as litter boxes.

Expert gardener’s tips: If the mulch has a shortcoming, it’s that fresh pecan shells may attract squirrels scrounging for nut remnants for a few weeks after spreading it.

How to Apply Pecan Shell Mulch

After your seedlings have emerged or your transplanting is done, spread your pecan shell mulch in a 2- to 3-inch layer over your entire garden. Keep it from touching the seedlings or it could trap moisture around them and cause damping off disease.

Mulching Container Gardens

For container gardeners with no access to pecan trees, a coffee grinder or food processer will turn the shells of store-bought nuts into attractive mulch minus the jagged edges.

The Juglone Factor

As hickories (Carya spp.), pecan trees produce juglone, a compound toxic to many other plants. The juglone is most concentrated in their leaves, which explains why almost nothing grows beneath the trees unless the leaf litter is promptly removed. The amount of juglone in the shells, however, is too small to prevent their use as mulch.

As we all know, yesterday was National Pistachio Day. Save those pistachio shell hulls. Cathy Isom tells you why you should recycle pistachio shells. That’s coming up on This Land of Ours.

Empty pistachio shells are useful for recycling in several ways. If unsalted, the shells need not be washed and dried before reuse, but washing is simple if that is not the case.

Practical uses include:

  • as a fire starter; kindling to be used with crumpled paper;
  • to line the bottom of pots containing houseplants for drainage and retention of soil for up to two years;
  • as a mulch for shrubs and plants that require acid soils, as a medium for orchids;
  • and as an addition to a compost pile designed for wood items that take longer to decompose than leafy materials.

Shells from salted pistachios can also be placed around the base of plants to deter slugs and snails.

Many craft uses for the shells include holiday tree ornaments, jewelry, mosaics and rattles.

Research indicates that pistachio shells may be helpful in cleaning up pollution created by mercury emissions.

I’m Cathy Isom…

“Every oak tree started out as a couple of nuts who stood their ground.” -Anonymous
Yes, we may be “composting nuts” but this post is actually about composting nuts, you know, walnuts, pistachios, and almonds. More specifically about composting their shells since we will likely be eating the nuts.
That’s a Tough Nut to Crack
Nuts are supposed to be tough. They are built to withstand forces of nature like torrential rain storms, freezing temperatures, and squirrels.
As you might imagine, whole (unshelled) nuts take a long time to break down (and may even sprout) in your compost bin.
So, the first rule of nut composting is EAT YOUR NUTS. Raw, glazed, on a salad, in cookies, whatever. Crack ‘em, eat ‘em, and then compost the shells.
Nuts and Bolts Nut shells are high in carbon, so be sure to balance with high nitrogen material like food scraps. Also, know that nut shells take a while to break down so you may need to screen them out once or twice.
But if a few pistachio shells incorporated in your soil with your finished compost drives you nuts, you probably need a new perfectionist-friendly hobby. Like building tiny ships in a bottle.
Warning: May Contain Traces of Nuts
I issue two warnings regarding Black Walnuts and salted peanuts.

  • Use caution when composting Black Walnuts. These are the native walnuts that look like green tennis balls on the ground not the English walnuts you buy in the store.

Black Walnuts contain a chemical called “juglone” which inhibits the growth of many plants, including tomatoes. The OSU Extension recommends composting Black Walnut bark and shells for at least 6 months to make sure the “toxic” juglone has broken down.

  • If you enjoy unshelled salted peanuts, beware. Too much salt in your compost is a bad idea which you will add if the peanut shells are still salted. Rinse the salt off in the sink before adding to your compost.

Otherwise, go nuts with your nuts.
Have you ever composted nut shells? How long did it take them to break down?

Composting walnut shells?

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One of the greatest things about nuts is their versatility. You can add flavor and texture by throwing a few walnuts onto a salad or some chopped pecans into chocolate chip cookie dough. Dreaming up new ways to cook and bake with nuts is easy, but one question remains—what to do with the shells? It just seems like a waste to throw them out.

Sure, you can add them to your compost heap, if you have one. Or just throw them in the bin with your other organic waste (you seperate your garbage and recycle glass, aluminum, and plastics, right?). But for the creative and the crafty, here are a few ways to do more with the “discards” from your nutty snacking.

Rogue Creamery, a great cheese company based in Oregon, hit upon a creative use for hazelnut shells: using them to smoke their cheese. One of Rogue’s most popular varieties is Smokey Blue, a blue cheese cold-smoked for 16 hours in Oregon hazelnut shells. The hazelnut shell smoke adds a mild, nutty nuance to the cheese, balancing the rich and pungent flavors. I also remember an episode of Iron Chef America where Bobby Flay smoked ribs with peanut shells.

Some people place empty pistachio shells at the bottom of flower pots to help with drainage. Or use them in homemade maracas and other noisemaikers for kids.

Have you ever cooked or crafted with empty nut shells?

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