Raised Beds for Veggies
Boxing clever in the veggie garden
Want to make your veggie garden more productive? Raised beds provide better drainage (which veggies love) and a friable mix that makes it easier for the roots to draw up water, oxygen and nutrients, especially in gardens with clay, sand or very stony soil. In areas where it is hard to garden, a raised bed can be made on top of hard surfaces (even paving) where it is impossible to dig, or in small gardens where there is not enough space for conventional veggie beds. It is also a solution for sloping areas.
The greatest appeal of raised beds is that soil quality can be controlled, and weeds kept out if weed-free soil is used. Raised beds also allow for a longer growing season because the soil heats up quicker in spring and is easier to work. In autumn or early winter the bed can be converted into a cold frame by covering it with glass or plastic.
Types of raised beds
Even in gardens with ordinary soil, a raised bed improves productivity. Mix additional topsoil, compost and organics with the existing soil so that the final bed is at least 30cm higher. Shore up the edges with bricks, stones or other materials to prevent the soil from washing away.
Instead of a bed, make a series of narrow raised rows, with paths in-between. The gardeners of yesteryear shovelled the soil, mixed with extra compost, into gently mounded rows and planted veggies along the top of the mound. It works well if space allows a series of rows. Don’t make the mounds too high or the water runs off.
Make a wooden frame that acts as a box with no bottom or top, and fill it with good quality soil. It looks neat and can even be used as a centrepiece. An entire veggie garden can be constructed in this way. Weed-guard cloth laid on the bottom will stop invasive roots coming through. Use untreated wood, and the thicker it is the longer it will last. Avoid creosote-treated wood, which releases toxins.
Used tyres are a great budget option; they just need to be big/deep enough to provide good depth of soil. Tyres can be placed directly onto the soil or on paving, with weed-guard cloth as a base to prevent the soil from washing away.
Don’t know what to do with an old chest of drawers? Pull out the dresser drawers and fill them with soil. Plant herbs or other shallow-rooted veggies, and even some trailing veggies. It’s neat and rather quirky. Builders yard specials Cement bricks (with a hollow core), loffel stones, and even recycled masonry can be used as retaining border for a raised bed. They are easy to put together. Fill the hollows in the cement blocks with soil for extra planting space for herbs or companion flowers.
Square-foot gardening uses raised beds (usually with a wooden frame), 1m x 1m, which is further divided up into a grid, with each block corresponding roughly to the size of a foot. This provides enough space for 16 different crops, so companion planting and diversity is easy to achieve. The benefit of this bed is that you tend to sow what you need and not over sow, because of limited space.
Best veggies for raised beds
- Root veggies like beetroots, carrots, parsnips and radishes like loose, freedraining soil. If you have heavy, sticky soil, a raised bed is ideal for them. Make sure the soil is free of stones and sticks that could cause misshapen roots.
- Leafy greens (spinach, kale, lettuce, rocket) are far more productive in fertile soil that drains well. Because the soil in raised beds warms up quicker, greens can be planted out earlier and yield more before summer’s heat.
- Tomatoes, brinjals and peppers are heavy feeders, and it makes sense to grow them in a separate raised bed with extra added compost. Don’t overcrowd the plants, and make sure the bed is deep enough to accommodate their roots. Staking the tomatoes may be a problem in the looser soil.
- Potatoes will also do well if grown in a raised bed if the level can be raised as the plants grow, by mounding up the soil around the shoots. They also like soil that drains well and should be given plenty of space for the roots to spread.
- Don’t make the bed too wide, as you need to be able to easily reach into the centre.
- Laying chicken wire on the base before building up the bed can keep out burrowing animals like moles.
- Vegetables like salad greens, Swiss chard, beetroot and others that don’t need space to develop a large head (like cabbage or cauliflower) can be planted a little closer together. That is because the soil is more fertile that ordinary garden soil and water use is more efficient.
- Plant vining vegetables, like cucumbers, on the edge of the raised bed so that their growth can trail over the side.
- Improve productivity even more with vertical structures like trellises, tepees or obelisks.
- With each new season, fill up with new soil and compost to maintain fertility.