Bedding Down, or, What’s with the Raised Beds?

Ah, winter, when the garden is covered in slush and the mailbox is full of garden catalogs. I received my Gardener’s Supply Company catalog a couple of days ago and spent some time fantasizing¬†about what a perfect-looking garden I could have if only I had several thousand dollars at hand. And this year, Gardener’s Supply seems to have more raised beds than ever.

I’ve always loved the look of raised beds, partially because they give the kitchen garden that characteristic potager look. Raised beds warm up more quickly in the spring, they keep you from stepping on the soil, which keeps the soil loose and makes it easier on the plants, and they promote close-set planting, which conserves water and mulch. They also keep the soil out of the paths, which makes the garden look tidier and keeps you from tracking quite as much mud into the house.

I have several raised beds in the back garden I made from 2″x 6″ lumber and filled with the Mel’s Mix outlined in All New Square Foot Gardening. No question, they’re a good use of the available space, especially after I added some trellis made of electrical conduit and netting behind them.

But raised beds do have a few drawbacks. They drain quickly, which is an asset if you have heavy clay soil but disastrous in a dry climate (where you should instead make sunken beds). If you make them of wood, the wood eventually rots and has to be replaced. But the main drawback for beginning gardeners and those of us who prefer not to spend a fortune on our gardens is that they can be expensive to create.

In addition to creating the shell of the bed (from lumber, bricks, concrete, or what have you), you still have to fill that puppy with a growing medium. The Mel’s Mix I mentioned before is one-third mixed compost, one-third peat moss, and one-third vermiculite, which is basically a puffed-up mica that holds water. Mel’s Mix makes a sensational growing medium, more akin to what you find in nursery pots than in the ground in your back garden. But 1. the ingredients ain’t cheap, and 2. there’s some concern about the environmental impact of harvesting peat moss.

So what’s a beginning gardener to do? For one thing, it helps to remember that you can have a raised bed without sides. The trick is to establish permanent paths and never step on the beds. Make your beds no wider than 3′ or 4′ across so that you don’t have to step on them, and the soil in those beds will gradually rise as you add compost and work the soil, while the soil in the paths becomes compacted from your walking on it. Voila! Raised beds without the sides!

If you really, really want traditional raised beds, here are some tricks for making them less expensive:

1. Use recycled wood for the sides. Do not use pressure treated wood, which contains poisons that leak into the soil, and make sure there’s no paint on the side of the wood that comes in contact with the growing medium. Cedar and redwood are naturally rot resistant and naturally more expensive.

2. The thicker the wood, the longer it lasts. I prefer to use sides that are 2″ thick if at all possible. If you plan to make your bed longer than about 4′, the weight of the soil may cause the bed side to bow out. Plan to drive a stake on the outside of the bed to help keep the wood in alignment.

3. If you’re putting the bed on existing grass, you might want to lay landscape cloth below the bed to prevent grass from coming into the bed. I prefer to lay new beds on ground that’s already had the grass killed (usually by smothering it over the winter with a thick layer of newspaper and mulch), so I don’t use the landscape fabric.

4. Plants need a combination of nutrients and soil to hold onto, which is why you don’t fill the bed with just compost. For a good growing medium that’s still pretty affordable, I recommend about half topsoil and half compost. While you can buy these in bags, it’s much cheaper to buy them in bulk. Borrow a pickup truck or have compost delivered to you. Check for places that sell mulch in bulk; they often have compost too. The more varied your compost, the better. Add compost from your own pile or aged horse or cow manure if you’re lucky enough to know a farmer.

Raised beds are a beautiful way to add structure to the garden, and they have the added appeal of instant impact. For a step-by-step guide to building raised beds, check out All New Square Gardening by Mel Bartholomew.

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