A while back, I realised just how much of my kitchen scraps could be repurposed for the garden, and that included walnut shells. At first, I wasn’t sure if they had much to offer, but after doing some research and experimenting, I found walnut shells are more than just compost material—they can actually help the garden thrive! Here’s how I use walnut shells as a natural, waste-free fertiliser to keep my plants happy and healthy.
Why Walnut Shells Are Great for the Garden
Walnut shells might seem like they’d take ages to break down, and they do—sort of. While they won’t decompose quickly like other scraps, they still offer something valuable: they’re rich in carbon, which makes them fantastic for soil structure and water retention. By adding walnut shells, I found my soil not only improved in texture but seemed better at holding moisture, which was a real bonus during the drier months.
Another plus? Walnut shells discourage certain pests, especially when used in mulch form. It turns out that the tough, jagged shells create a bit of a natural barrier that slugs and snails don’t love to cross.
How I Use Walnut Shells in the Garden
1. Crushing and Adding to Compost
The first way I began using walnut shells was by breaking them down and mixing them into my compost. Since they’re tough, they need a little help breaking down faster, so I gave them a good whack with a hammer or crushed them using a food processor (just make sure to clean it well afterward!). Mixing these crushed shells into the compost gives it a carbon-rich boost, balancing out the “green” nitrogen-heavy waste like veggie scraps.
Adding walnut shells to compost felt like such a win—it’s using every bit of something that would’ve otherwise gone in the bin. And the best part? The compost mixture seemed even more balanced and rich.
2. Mulching with Walnut Shells
One day, I spread a layer of crushed walnut shells around the base of my tomato plants, and it worked wonders. Not only did it look nice, giving a tidy, rustic appearance to my garden beds, but the shells helped keep the soil moist by providing a protective layer. Plus, they helped keep weeds at bay since the shells are difficult for weeds to push through.
I did notice fewer slugs in areas where I used walnut shells, which felt like a bonus. The rough texture seemed to act as a natural deterrent—something I’d take any day over chemical pesticides!
3. Improving Drainage in Potted Plants
If you’re like me, you probably have a few pots on the porch or patio. I found that using walnut shells at the bottom of these pots improved drainage without taking up too much space. Walnut shells allow water to flow through while keeping the soil from compacting too much, which is great for root health.
It was a revelation! Instead of always adding stones or gravel, I had an eco-friendly, free solution. And as the shells gradually break down, they’re adding to the soil mix, which is a win-win.
Tips for Using Walnut Shells Safely in the Garden
Now, walnut shells come with a bit of a warning: they contain juglone, a natural compound that can be toxic to certain plants like tomatoes, potatoes, and some flowering plants. While I haven’t noticed any ill effects myself, I’ve always been mindful of where I place them, sticking to less-sensitive plants just to be safe.
Here are a few things to keep in mind:
Avoid Juglone-Sensitive Plants: If you’re growing tomatoes, peppers, or eggplants, avoid using walnut shells around them. Juglone can inhibit their growth and lead to wilting.
Crush for Faster Decomposition: Walnut shells decompose slowly, but crushing them speeds things up. A quick bash with a hammer, or a couple of pulses in the food processor, does the trick.
Layer Moderately: While walnut shells are great in moderation, too many can make the soil too alkaline or create a barrier that prevents water absorption. A thin layer is usually all you need.
Final Thoughts: Turning Waste into Garden Gold
Using walnut shells in my garden has been surprisingly rewarding. It feels good to find a purpose for something I’d previously tossed out without a second thought. Plus, it’s sustainable, and my plants genuinely seem to benefit from the added structure and protection.
If you’re into the idea of low-waste gardening, try keeping a little jar of walnut shells next time you have a handful. Even if you only sprinkle them here and there, you’ll feel a bit closer to nature, making use of what you already have. So next time you’re snacking on walnuts, remember: those shells have hidden potential! Happy gardening! 🌱