How to Build a Keyhole Raised Garden Bed

I am endlessly intrigued by interesting and unique ways of approaching the ordinary.

Especially when it comes to gardening. You probably know that about me by now. When I was introduced to hugelkultur, my personal perspective on food production was changed forever. It was no longer as simple as sticking a seed into the ground, giving it water, and hoping to grow something. Now I question everything that I do.

  • How can I feed the soil, as well as my family?
  • How can I limit resources, such as water and outside energy sources?
  • How can I control pests in a natural way?
  • Am I leaving behind something that is better than what I started with?

There are always endless questions. Because I care. And chances are, if you’re reading this post, you care too.

So I’m always on the hunt for ways to do my gardening in a smarter, more respectful way. That is how I stumbled upon the idea of keyhole garden beds. And after 2 growing seasons of using this method, I figured it was time to share with you all here.

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The keyhole raised garden bed was developed in Africa. There, drought is prevalent as well as extreme heat. Now, here in NE Minnesota, we don’t typically deal with either of those things. But the good news is, no matter where you live or the weather conditions, you can greatly benefit from this type of gardening. But I’ll bet those of you who suffer with a hot, dry climate just might be a little extra excited to find a method that is tailor-made for you.

What drew me to the keyhole was that its design is similar to hugelkultur, with the added twist of a compost ring right in the center that feeds the bed all season long. I’d already seen the benefit of hugelkultur on its own. Could it possibly get any better? Yes. And today, I’d like to share with you my complete how-to, start-to-finish instructions on how you too can experience these results in your own garden.

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First things first, there’s about a million different ways you can go about designing your beds. Some get real fancy and use bricks or rocks or other retaining walls for their beds. I prefer the easier, more natural method of construction, because that is my personal style. You do what your little heart desires. There really isn’t one way or the other that’s better. (I will post a link to some design ideas at the bottom of this post).

To begin, choose your location. It should be in full sun. I decided to build my bed around a problem area in my garden. This spring, we’d had a large dirt mound moved from what is now the southwest corner of my garden. What was left behind was a massive rock that we couldn’t move by hand, as well as a large tree stump that was still well rooted in the ground.

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What I’ve really come to appreciate about permaculture is the way it encourages you to turn a problem into a solution. And for several days, I mulled over how I was going to take care of this problem. And that is when I realized that using this area for my keyhole bed was perfect.

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Keyhole beds are fashioned into a round or horseshoe-shaped design, with a compost ring in the center that is reached via an access point in the bed. The compost ring that I happened to have is quite tall. Therefore, the large rock would be perfect for my access point to the compost ring, with its size benefiting me as a step up to it. To make yourself a compost ring, you can use all sorts of materials: chicken wire, fencing, wire mesh, even bamboo sticks. Create a tube that is approx. 1 foot wide x 4 feet tall. I used a ring I had on hand, which is closer to 2 feet wide.

I started out by using logs and random pieces of rotting wood to map out the shape of my bed. Place your compost ring at the center of the bed, and measure out 5-6 feet from the ring all the way around it; this is the typical size of a keyhole bed. Be sure to leave yourself an access point so that you can get to your compost ring throughout the season.

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Fill in the base with all sorts of woody debris. Otherwise, consider cardboard, newspaper, leaves, etc. As you can see, I’ve incorporated Problem #2 (large tree stump) into the far-right corner of my bed. Eventually, over time, that stump will decompose just like the rest of the wood in this bed.

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Continue to layer the bed, with the largest materials on bottom. I added a good layer of manure and animal bedding just as I do with my hugelkultur beds. You can layer in compost if you’d like.

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The final layers are a good 3-4 inches of good garden soil and then a heavy layer of straw to keep the weeds away.

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You are now ready to plant! Or, if you’re preparing this bed in the fall, it is ready to have a nice season of rest in preparation for the growing season to come. Whatever you choose, begin using the compost ring right away. To it, regularly add kitchen scraps, coffee grounds & filters, grass clippings, leaves, shredded newspaper, and other compostable materials. Water it as well. As the compost items begin to break down, they will feed the bed, giving it a steady stream of nutrients that will make your plants so incredibly happy.

Here are some photos that I took throughout this past growing season, just so you can see how well this really works.

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In this bed, I planted tomato plants along the outside, along with nasturtium, dill, calendula, and marigolds. Around the inside (along the compost ring), I planted cucumbers which were able to climb up the ring as they grew. This polyculture of companions, in addition to the constant feeding of the composter combined with the hugelkultur construction of the bed resulted in huge, productive plants. A with my other hugelkultur beds, I almost never had to water- even with an extremely hot, dry month of July. When I watered, I watered right into the ring so that it could give the plants a good shot of nutrition while watering the roots at the same time. It has not been watered at all the past two months.

I took a quick video of this bed. I used my tablet to do so, and I apologize for the narrow view that resulted. But hopefully you get the idea 🙂

I hope you give this method of gardening a try. I’d love to see and hear about your results.

For further reading and design ideas, here are a few resources for you:

http://www.sendacow.org.uk/lessonsfromafrica/resources/keyhole-gardens

http://www.texascooppower.com/texas-stories/nature-outdoors/keyhole-gardening

About yellowbirchhobbyfarm

Hi! I’m Erin, a 19th-century homesteader at heart. Here at Yellow Birch Hobby Farm we practice self-sustainable living by way of organic gardening, canning & preserving, raising a variety of livestock, hunting, foraging, and cooking from scratch. And here at our blog, we share it all with you! So glad you’ve found us.

6 comments on “How to Build a Keyhole Raised Garden Bed

  1. Wow! This looks amazing. I have so much straw/chicken or duck manure bedding that I now have a great use for! It takes forever to break down in my compost bins, but building a keyhole hugelkulture garden is a great way to use it up! I’m already planning ……

  2. I think I’m ready to build either the hugel bed or the keyhole bed….all my compostable (is that even a word?) scraps go to my chickens so I’m wondering what to put in the compost tube in the center of the keyhole bed? I may try both methods and see which works best. The limited watering benefit really draws my interest. Thanks for all your informative posts – great blog.

    • Hi, Catherine! Both types of beds are awesome. Other compostables could be grass clippings, leaves, shredded newspaper, shredded cardboard, paper towels, coffee grounds & filters, dryer lint, egg shells, twigs, and other things you shouldn’t give your chickens such as onions and orange peels. Hope this helps get your wheels turning. Have fun and thanks so much for reading!

  3. I lived in apartments most of my life, but have always had small potted herb gardens.

    I just moved into a house and totally loved the keyhole garden boxes at Costco, but are way to expensive for me so I figured I could find someone who has made one!

    Thank you for your post! I’m totally a fan for sure!

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