Refreshing the Keyhole Garden in Winter

January is the time to clean up the keyhole garden and get it re-planted with late winter / early spring crops

The keyhole garden repaired, reloaded, and ready for the 2025 season

This coming March will be the 6th year with our keyhole garden and I’m still wowed by the productivity of this unique raised garden bed.

Not only has it produced fresh herbs and vegetables year-round since it first went into service, but, thanks to a centralized compost bin that both feeds and warms the bed, many of the plants in the bed continue to produce for far longer than they do elsewhere in the garden (I just pulled some sweet pepper plants that were almost three years old).

While the keyhole garden is probably one of the easiest types of raised bed to maintain, that doesn’t mean it’s entirely maintenance free. I’ve discovered there are still a few things you need to do on a regular basis to keep it in top condition.

Mid-winter is the slowest part of the year for the garden, so I use it as an opportunity to make everything ship shape before the warm weather returns and we get back into the busy growing season again.

1) Clear out the old plants

Keyhole garden with what remains of the fall plants

Believe it or not, I still had tomatoes and peppers growing and producing in mid-January. The tomatoes had only been there since June, but the peppers had been in there since I transplanted them back in the spring of 2022. While they were all still viable, they were leggy and not in the best of shape, so I decided to get rid of them and make room for some other stuff I had growing in the greenhouse. I also pulled the dead pumpkin vines, some carrots gone wild, growing from the seed I left in there last spring, and a bunch of bean stalks, probably sprouted from bean pods I missed picking back in August.

Once the bed was cleared of debris (except for the very back where I had new lettuce growing), I had a clear view of the soil level and the wood that makes up the keyhole garden’s walls.

2) Raised bed repairs

Turns out that the pipe strapping that makes the bands holding the bed together had rusted out in the two spots where they begin the curve into the cutout that makes the keyhole access to the compost bin.

Straps broken and the walls in need of repair

As you can see from the photo, the boards at the outermost curves were splayed out, spilling soil and blocking a portion of the concrete walk.

To repair the bed in those two spots I dug out the soil against the wall and pulled the boards upright once again. Then I secured the boards by screwing a new length of pipe strap onto the upper portions, making sure it was anchored such that it wrapped the entire curve.

Walls repaired with fresh pipe strapping

The rest of the bed’s walls were in fairly good shape, so I didn’t need to do any more work on it.

The one other “fix” I made was to remove about half of the material from the compost bin. We had been adding kitchen scraps, weeds, and other compostables to the bin at such a rate that it was growing faster than the compost critters could reduce it and the material was reaching the top of the bin.

Fortunately, because the soil was dug out to repair the bed walls, I had a couple of spots to drop the compost into. I shoveled out a bunch of the material – both fresh and partially broken down – and dropped it into the bottom of the holes. It’s basically the same thing I would do with a lasagna garden, layering fresh organic materials in the bottom of the bed and topping it with soil.

3) Add more soil to top the bed off

After a long growing season, the soil level in the bed dropped a little more than 4 inches. Additionally, with so much intense plant growth, the organic matter was heavily depleted leaving soil that was high in sand and minerals but low in nutrients and water retention. I needed to get the soil back in balance. (https://sagesacre.com/2023/06/10/garden-hack-how-to-make-good-garden-soil/)

Rather than re-layering the bed, which takes a lot of time and effort, I decided to do the quick thing and top the bed off with a couple wheelbarrows loads of fresh compost and well-rotted manure.

My 2-1 manure-compost mix

I went with a mix of 2 parts manure and 1 part compost because I not only wanted better water retention, but I also wanted to make sure there was plenty of freely available nitrogen in the soil both for the soil microbes and the winter seedlings I planned on transplanting right away.

In all, it took about 12 cubic feet (roughly two wheelbarrow loads) of compost/manure mix tilled into the bed to top it off. Once that was finished, I watered it well to allow the soil to settle and remove any big air gaps that might be left.

The keyhole garden topped off with 2 wheelbarrows of compost/manure

4) Plant late winter / early spring crops

Fortunately, here in San Diego the temps only dip below freezing a few nights a month, so transplanting cold-hardy crops outdoors isn’t an issue. (It also helps that the keyhole garden produces its own heat, so the soil stays warmer than the surrounding areas.)

Winter seedlings in the greenhouse waiting to be planted

Back in December started a bunch of winter seedlings in the greenhouse – all of which were now ready to transplant. I didn’t need to worry about hardening these off because I run a cold (unheated) greenhouse, so these plants were already well acclimated to the nighttime chill.

Ultimately, I transplanted planted lettuce (Ice Queen), cabbage, broccoli, Swiss chard, cilantro, and dill into the keyhole garden. I also left some carrots, lettuce and a couple of beans that had volunteered themselves in the back of the bed, so we’d still have some veggies to harvest while waiting for the others to mature throughout the winter.

The keyhole garden repaired, reloaded, and ready for the 2025 season

Now we wait

All that’s left to do now is make sure the plants are watered and cared for. Somehow the chickens found out that the bed was reloaded, so I’ve already had to chase them out of there twice, costing me a cabbage seedling and some lettuce. I’ll have to be more vigilant about making sure they stay in their part of the yard.

Otherwise, everything looks good. The 2025 gardening season is off to a good start!

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