A few weeks ago I wrote an article on biochar , a centuries old technique for adding nutrients to the soil and retaining them. The build process is the same either way, apart from the fact that with the bigger timber we screw them together rather than nailing. Some paint-on wood treatments: which use acypetacs (such as ‘Cuprinol’) are believed to be safer than the above treatments. Do not use pressure treated wood in your vegetable garden, as the chemicals can leach into the soil and also your vegetables! There are some companies that are now making less toxic treated lumber but I would stay away from it. If you choose to use wood, build an organic garden with untreated cedar for best results.
Modern wood treatments do not contain potentially harmful heavy metals, so are safe to use. Plus, you can line the bottom of your beds with netting before you build to stop burrowing pests. We love all these examples, but we know there’s still plenty of garden beds out there that haven’t been made yet. In 2003, the EPA banned the sale of lumber treated with chromated copper arsenate (CCA) for residential use.
It’s called Botanical Edging, the reason being, if you have something as large as a Botanical garden with thousands of beds, it’s not practical to install edging, so you just dig them. In my opinion, untreated lumber is cheaper, easier, and a much healthier way to go, as compared to treated wood. Here’s a raised garden that’s been arranged in a geometric shape, not just for looks, but for function.
Garden beds can be sunken to lower the garden to where water is more easily accessible by plant roots, and more likely to retain water when it rains. Because the sides are exposed to the weather, watch out for your raised beds to dry out faster than the surrounding ground. If you’re thinking about building a raised vege garden, the first step is deciding where it’s going to go. Veges like a nice balance.
They have a formulation that you can treat wood with and it will start the petrification process and they say that once treated, wood will not rot or decay. Just remember that good drainage is important for a raised garden so don’t run the polythene sheet over the bottom of the garden. Composite (a bit ugly) and borate treated lumber (expensive but nice) will typically last much longer and have are often favored by those who care about evil chemicals. So true about going up rather than digging down- this is how I’ve built all my new beds in the yard and have improved the existing ones too.
To take full advantage of the deep rooting potential with raised beds, work up the base soil by rototilling or hand-digging before bringing in additional soil. The basic technique used in close-row, block planting is to eliminate unnecessary walkways by planting vegetables in rectangular-shaped beds or blocks instead of long single rows. We’ve had a couple of pretty good years here with the garden but there are never any guarantees. Fertilizer can be added at planting time, at a rate of one pound of 6-6-6 to each 100 square feet of raised garden bed. However, they don’t penetrate as deep into the wood and probably need re-treating more often.
Construction materials – A simple way to construct a raised bed garden is to use construction lumber (2 by 4s, 2 by 6s, 2 by 8s, and 2 by 10s). Also, because a temporary bed has no wall, the soil may erode from the top of the bed into walkways or down hillsides. Raised garden boxes have looser soil, which is ideal for root crops, providing a more optimum soil environment for root growth. I’m currently researching how best to approach some raised garden beds for food growing (the usual herbs and veggies). After planting, you can add mulch (try pine straw or mini pine bark nuggets) as the finishing touch, an especially important one to raised beds, which can be prone to drying out.