How to Combine the Popular Keyhole Garden with Your Existing Raised Beds

A while back, I saw an article about keyhole gardens and thought, “Wow! That might actually work!” But it was going to take a wee bit of planning. See, my husband already had plans for the garden. And they included raised beds, not a keyhole garden.

keyhole garden and raised bed combined

If you haven’t heard of a keyhole garden, they are built on a sort of wagon wheel design, with a large compost pile in the center and your plantings radiating outward from there.

keyhole garden diagram

I can see a keyhole if I think about it, but mostly, I see a wagon wheel. You leave a section open to allow easy access to the compost pile so you can keep adding to it throughout the season. Then every time it rains (or you water your compost pile), all those delicious nutrients flow out to feed your plants.

Fortunately, it is not completely incompatible with a raised bed. Five gallon buckets placed in the center of the garden serve as the compost pile and everything else remains the same. There are some distinct advantages to this combination.

Advantages of this gardening system:

  • The buckets in the center of the garden allow you to water your garden from underneath. This encourages plant roots to go deeper into the soil and you lose less water through evaporation.
  • Every time you water your plants, you fertilize them as well.
  • Raised beds are nice, particularly when you have poor soil. Instead of spreading compost to an entire garden and then tilling it in, you can apply it to a smaller area, right where the plants are.
  • Since the area is smaller and more well-defined, it is easier to work the soil without stepping on it. The soil doesn’t compact as much, keeping it loose and workable.

Building the raised beds.

When we started, I had a pretty good idea of what I wanted these to be. Since we were going to be incorporating compost in the center, I went ahead and made them bigger to begin with.

Well, had our church’s youth group make them bigger, anyway. They came out and built raised beds for a day and we donated money toward their summer camp. They each measure 5′ by 5′ and are 8” high. They have two supports on each side that go down 6” below the bed to anchor it in the soil and help keep the pressure from bowing the wood.

My husband took care of setting them in the garden and leveling them. Because he’s awesome like that.

We also added fencing to the west side to support plants like tomatoes, peas and beans. We still need to add the supports, but they are working really well in my head.

Preparing the buckets.

So far, I mostly directed other people. That’s the fun of having other people build your beds for you. But this part I could handle. I purchased a food grade bucket for each of the six raised beds. These serve as the compost pile at the center of each raised bed. I then drilled four rows of holes around the entire bucket, plus one in the bottom. I also drilled a hole in the lid big enough to put the hose in so we don’t have to take the lid off to water it.

The idea is, we will fill these buckets with compostable materials. Since we have pigs, we really don’t have kitchen scraps, but we have plenty of manure and spent hay.

When it is time to water, I just fill up the bucket. Nutrient rich water trickles out of the holes, both feeding and hydrating the plants. Since the compost is diluted before being added to the soil, I don’t really have to worry about it getting too “hot,” and thus can continue adding to the compost buckets throughout the season.

Preparing to plant.

We keep animals, therefore we have a steady supply of manure for gardening projects. Last spring, we scraped the barn floor and left all of that manure, straw and dirt in a large pile next to the barn. It spent a whole year turning into a rich, black compost. We then used the tractor to haul it all to the beds. Since we are essentially planting in compost, I wasn’t too worried about how deep we made the beds. They are just sitting on dirt, not weed cloth, so the roots will go down into the soil below.

Filling a keyhole garden

We placed a hole-y bucket in the center of each raised bed and piled the compost all around. We filled them, but they have since settled to an average of 4 – 6 inches of compost per bed. The depth actually kind of depends on how good the children were at not standing on them while they were planting.

Filling the buckets.

Since our garden is starting off with so much compost, I didn’t actually want to put a whole bunch of manure in the buckets or the soil would end up with too many nutrients. For this year, we put a bit of spent guinea pig bedding in each one to provide a base to start attracting worms and filled the rest with straw we pulled out of the sheep pen. It has a lot of urine and manure mixed in with it, but since it is mostly straw, It won’t decompose very fast.

At the end of the season, we will empty the buckets and refill them. Next year, I anticipate filling them with compost. I’ve read that when doing it this way, you can even put uncomposted poultry manure in the buckets. I don’t quite trust it, however, so may test that theory in one garden before adding it to all my buckets!

Selecting the plants.

You can put just about anything in a raised bed garden that you can put in a regular garden, you just need to be mindful of the space requirements.  My children each got to select the plants for one box, so we have an assortment of tomatoes and peppers as well as onions and marigolds.

Planting a Keyhole Garden

They sprinkled lettuce, carrot and radish seed over the whole garden in hopes that they will get to harvest those before the peppers and tomatoes are big enough to compete with them.


Anyone who has followed my blog or facebook page for long knows I have a long standing animosity toward mulch. It just doesn’t seem to work for me here, in the 6th windiest state in America. I know it is good for the soil. I know that it helps retain water.

Mulching a Keyhole Garden

And I know that almost all the mulch I lay down will be gone within a week.

Seriously, my kids’ kiddie pool took flight and I never saw it again. How on earth will straw stay put in a garden?

So far this season, however, the mulch seems to have stayed put. I am using mostly straw out of the sheep pen along with some pine bedding that was intended for the guinea pigs but was left outside and got soaked. The real trick, however, is that it was laid down on the soil in a raised bed. None of it reaches above the wood and therefore receives a little protection from the wind.

I am kind of excited.

Watering the garden.

The garden vegetables we plant need approximately 1 inch of water per week. But what does that mean? How do I measure an inch of water as it comes out of the garden hose? According to the University of California Master Gardener Program, you need 0.623 gallons of water per square foot of garden space. For my 5′ X 5′ garden, that comes out to 15.575 gallons per week.

How convenient that I have a five gallon bucket right in the center of the garden!

Now, filling that three times a week won’t quite cover the needs of my garden. My buckets are, after all, full of other stuff. Still, I am doing two things to conserve water: mulching and watering from the under the soil. During the heat of the summer, I may have to fill the buckets almost every day, but they are sized about perfect for this size raised bed.

Or I could use a sprinkler and lose 25% of the water to evaporation. I think the buckets sound way better!

Interested in Keeping Up With Our Keyhole Garden?

This blog is about our life here in the country and educating our children through it. If you would like to see how this garden progresses, why not sign up for my newsletter? There is an option to only receive farm and garden updates if homeschooling isn’t really your thing.

Gardening with children.

As you probably noticed, we do our gardening with our children. It is a wonderful learning experience for them and gives them such a sense of accomplishment. Plus, they just love it. We homeschool so gardening is very much a part of our health and science curriculum, but anyone can teach their children through gardening. I even have a free mini-unit study that helps you teach your children about the parable of the sower while starting a garden together.

Happy gardening! And please drop me a note about your gardening projects. I love reading about what other people are doing in their gardens.

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3 thoughts on “How to Combine the Popular Keyhole Garden with Your Existing Raised Beds

    1. What you see in the picture is actually pine chips that was meant for guinea pig bedding, but it got forgotten on the back porch and soaked in the rain. I took the picture of that one because it was the prettiest. The others are mulched with spent hay out of the barn. You end up with a little more grass in the garden that way, but it was mixed with manure and urine and makes a good fertlizer!

  1. Hello Dana, I like your blog. You have described awesome tips for gardening, which is helpful for me. I want to make new garden for my new home. These tips will surely help me. I was confused before this blog. Thanks for sharing your blog with us.

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