How to Get Rid of Black Walnuts

When black walnuts start to fall, they come down in the hundreds. The green husks scatter everywhere, and the hard nuts can completely cover your yard. You need to get rid of them properly, but how?

Black walnuts contain juglone, a natural toxin that is harmful to many plants. So you can’t just dump them anywhere. In this article, we’ll talk about smart disposal methods for black walnuts.  

Whether you plan on harvesting, composting, burning, trashing, or ignoring them, we’ve got you covered with pros, cons, and hacks to take the headache out of this Autumn yard waste.

Black walnuts are edible so why would you want to get rid of them in the first place?

Dangers of Black Walnuts

 Unlike English walnuts, they’re a little more bitter and not easily removed from the shell. 

A single black walnut tree in your yard can produce a lot of walnuts. The walnuts start to fall in mid-September and will continue to fall through November. It’s a slow and steady process requiring continual cleanup. 

Walnuts can be a danger to vehicles if the tree is close to the road.

While you can safely drive right over them, they can easily become a distraction. It’s a different story for bikes and motorcycles however potentially causing an accident. 

Juglone Toxin

Inside their hard shells, black walnuts contain juglone, a natural toxin that is harmful to many plant species.

It can damage or kill plants like tomatoes, peppers, potatoes, eggplants, apples, blueberries, azaleas, and more.

There are however plenty of juglone-tolerant plants if your only option is to garden close to your black walnut tree.

 Composting leaves, hulls, and nuts or disposing of them near garden beds can leach juglone and hurt your vegetables and ornamentals. Also, stay away from mulch containing black walnut bark. 

Plants can also come into contact with juglone via the root system of a black walnut tree which extends about as wide as the canopy of leaves. This means that there will be juglone in your soil even after a tree is removed.

Can You Burn Black Walnuts?

A traditional fire pit is not a great choice as black walnuts produce a lot of smoke, especially if burned while still green. Some studies show that smoke from black walnuts can contain juglone which can be hazardous to inhale.

The best option for burning black walnuts is an outdoor furnace. This will mitigate the risks of breathing in smoke that could still contain juglone and add the benefit of free heat. 

This is especially alluring as in most states the walnuts begin to drop in the months of late September and October. Given a month or even two to dry, the timing is perfect for a first run of the season in your furnace. 

Here are some tips if you choose to use an outdoor wood furnace for disposing of black walnuts:

• Ensure your outdoor wood furnace was intended for burning organic materials like black walnuts. Follow all manufacturer guidelines.
• Operate the furnace at very high temperatures to promote complete combustion. This helps reduce toxic smoke production.
• Don’t stand near the furnace breathing smoke – always keep a safe distance.
• Consider pollution control features like afterburners or filters to reduce emissions.
• Monitor the burning process continuously and have fire safety equipment on hand.
• Allow ashes to fully cool for several days before disposing to avoid juglone issues.

Although more time-consuming, you can also burn only the walnut husks after harvesting the nutmeat.

Since it’s fire pit season make sure you know how to keep yours safe this year.

Can You Compost Black Walnuts?

You can compost black walnuts for sure, there are however some considerations that will certainly make your life easier.

It can take upwards of 18 months for a black walnut to completely break down. If you can slightly crush or use a hammer to crack open your black walnuts, it can cut the breakdown time in half, even quicker in hot compost. 

With a 6-9 month breakdown time, harvesting in September will ensure that your walnuts are fully composted for use in the springtime. 

Next comes the question of Juglone. 

Does Composting Break Down Juglone?

According to the OSU Extention Service the answer is yes as long as your compost pile is well maintained. 

Here are some quick tips to ensure your compost gets hot enough.

1. Mix together nitrogen-rich “green” materials like food scraps (avoid things like meat, cheese, bread, and sugar), grass clippings, or manure, and carbon-heavy “brown” materials like dry leaves, wood chips, or cardboard.
2. Combine these ingredients into a large piled heap, at least 3 ft x 3 ft in size. The bulk helps retain heat. A simple three-pallet compost setup works well for me.
3. Maintain a 40-60% moisture level, around the dampness of a wrung-out sponge. Too wet or dry will disrupt decomposition.
4. Turn and stir the entire pile every few days to circulate airflow. Oxygen is your compost pile’s best friend. This will also keep your pile from matting.
5. Monitor the internal temperature, aiming for 140-160°F. This indicates good microbial breakdown.
6. An expanded volume followed by your pile shrinking signals fast, effective composting.
7. Keep nitrogen, air, and moisture balanced for vigorous decomposition to hit high temperatures.

If you’re still unsure that your compost got hot enough, here is another list of juglone-tolerant plants that would thrive from your homemade compost. 

Can You Bury Black Walnuts?

If you’d like to get rid of black walnuts, burying them might be a great option. The depth at which you bury the nuts will determine whether you grow them or allow them to decompose underground.

For decomposition, you’ll want to bury the walnuts deeper than six inches underground. When planted at this depth black walnuts as well as most seeds will fail to germinate. Failing to germinate they will begin to break down beneath the soil.

Black walnuts have a very high nitrogen content and can actually enrich your soil. 

Key Take Aways

While dealing with lots of falling black walnuts in your yard can be a hassle, there are several effective strategies to properly dispose of them.

 Composting is one of the best ways to break walnuts down and derive nutrient benefits for your garden beds. Crush the shells first to accelerate decomposition and run your pile hot to neutralize the juglone toxin.

 Burning the walnuts in a high-temperature outdoor wood furnace is another option that allows you to harness heat value from the walnuts while mitigating risks if proper safety precautions are followed.

Whichever route you choose, exercise caution regarding the natural juglone toxin when working around black walnuts.

 Understand which landscape plants could be impacted and avoid mulching or composting near them. With responsible disposal practices for the walnuts, your fall yard cleanups can go smoothly, and you may even find some beneficial reuses for this prolific crop through composting or creative applications.

 Disposing of black walnuts is manageable once you know the best handling methods.

Walnuts bring squirrels and if your dog is like mine, you might use an outdoor run to keep the thrill of the chase at bay. After you’ve cleaned up your walnuts for the season use some mulch to give your dog run an easy upgrade.

Published by Luke H. on December 17, 2023

Edited by Luke H. on April 7, 2024