It’s hard to say enough good things about a keyhole garden. This raised bed isn’t just efficient and easy to maintain, but it’s also productive year round with a minimum of work.
Our winters here in San Diego county aren’t the cold and snowy ones they are in many other parts of the country, but the ocean to our west, mountains to our east, and all the hilly terrain in between makes for a lot of different micro-climates in the region.
Here at the Acre we’re about halfway between the Pacific Ocean and Palomar Mountain on the south side of the San Luis Rey river valley. Our micro-climate is equally influenced by ocean and mountains, a little warmer in the summer and cooler in the winter than the coast, but far more moderate than the hot and cold of the foothills just a few miles east. (Not surprisingly, this area is home to quite a few nurseries, avocado and citrus groves, and vegetable and flower fields.)
Winter lettuce and spinach in the keyhole garden
While the weather is more moderate than neighboring micro-climates, we still get a fair number of below-freezing nights, usually following on the heels of a Pacific storm or high pressure coming out of the desert. In late January and on into early March, it’s a cycle of wet days and cold nights occasionally broken up by a hot daytime Santa Ana wind followed by an even colder night (the dry air can bring overnight lows down into the mid 20’s F).
The wet weather and temperatures that can swing 60 degrees in a 24 hour period make it a challenge to grow any kind of vegetable, winter or summer, in the main garden, so we let that one rest and allow the “cleaning crew” (aka our chickens and ducks) to forage in it until mid-March.
The keyhole garden, however, is a different story. There, the high raised bed not only drains water more quickly, but the compost bin in the center leeches nutrition into the soil while keeping it several degrees warmer than the surrounding area. As long as the compost bin is happy and doing its organic magic, we can keep the garden planted and producing all year long. In fact, our keyhole garden is currently on day number 668 of continuous production.
The compost bin in the keyhole garden
Like all compost, the keyhole garden’s compost bin requires a good mix of dry-to-wet organic material as well as moisture and air circulation. For us that’s a mix of kitchen scraps (fruit and vegetable only), plant matter from other parts of the yard (cuttings, fallen oranges from the orchard, and a generous helping of leaves from the podocarpus tree at the front entry (which drops an incredible amount all year long).
Because we have long, dry spells between rain the winter, we keep the bin moist by not turning it too often – maybe once every few weeks or so. But after it’s been wet and cold for an extended period, like it has been for the past week or so, we’re a little more aggressive on compost maintenance, adding more dry material than usual, and turning it a couple times a week to keep it active.
Yesterday following a heavy rain, hail and two nights of freezing temperatures, I checked the keyhole garden’s status and was pleased to find that not only had the lettuce, spinach and broccoli survived, but the summer tomato and frying pepper plants over-wintering in it were also doing just fine.
I credit this to the compost bin, which as you can see from the video nearby, is doing splendidly. It’s wormy, rich and warm, exactly as we want it this time of year, which is why I love this garden so much.
If you’ve ever considered a keyhole garden, or just want to learn more about what makes it special, I recommend you check out my post from a while back. There you’ll see why it’s designed the way it is, and how I built my own. Hopefully, you’ll find it inspiring. I know if you build one of your own, you’ll be amazed at what it can do!