Create a Raised Bed Garden with our Easy Instructions for Growing Vegetables

Find step-by-step instructions for a raised bed garden for growing vegetables. Learn how to build raised beds, bed size, soil preparation, crop spacing, sowing and crop rotation and soil rotation for raised bed gardening. Raised beds are ideal for those gardeners who find that they want to plant over concrete, clay soil or other soils that are too hard to dig.

RAISED BED GARDEN: Materials

Raised beds can be built out of any suitable material that will give you the desired depth. For most vegetables, you won't need anything more than 6 inches in depth. You can use house bricks, concrete blocks, sleepers, treated pine logs, shutter board or even discarded, hard plastic paddling pools, old sinks or even a cut down corrugated water tank. There are also options where you can buy purpose built corrugated raised beds and wooden raised beds from gardening shops and outlets which are more expensive.

Another option is to outline to bed in large rocks and fill the center with soil. When the soil has reached the top of the rocks, then add another layer of rocks and fill the soil in to the top of the second layer of rocks. Make sure that the second row of rocks is placed just a little way in from your foundation level so as to minimize soil erosion when it rains, especially when the beds are still new and the plants haven't taken root yet.

RAISED BED GARDEN: Dimensions

As mentioned before, a bed built to a depth of 30cm is more than enough for root crops, including carrots and parsnips. For leaf crops you can get away with 15 cm. Your beds can also be built to waist height for those people who not only find it difficult to dig, but also find it difficult to bend.

The width of the bed will be determined by what is comfortable for you, as periodically, you will have to get in there to weed and harvest your crops. 120cm in width, or 4 feet, as long as you can access it from both sides, is ideal. If you can only access it from one side, then shorten it to that of an arm's length. The length of the bed is up to you.

The spaces left between the beds is comfortable at 45cm unless you need to push a wheelbarrow between the beds, then you will have to double it. But if you can, leave the space at 45cm, and find an alternative route for the barrow.

RAISED BED GARDEN: Bed Preparation

First line the raised garden beds with newspaper before you start adding your soil. A good mix is using sandy loam mixed with adequate amounts of organic material such as grass, leaves, coffee grounds, egg shells which have all broken down to friable compost and peat moss. Also mix in a good quantity of blood and bone, and chicken manure that has been well rotted. If your manure is fresh, wait 2-4 weeks before planting as the manure will burn the roots of your seedlings. Chicken manure is the best manure for growing vegetables because of its high nitrogen content. The only raised garden bed that you will want to use it sparingly will be for root crops, especially carrots as too much manure will make the carrots split.

RAISED BED GARDEN: Crop Spacing

Conventional spacing is using rows. However, when plants are staggered, they make the best use of space above and below the surface of the soil. This means very intensive planting, which can give considerably higher yields then conventional row cropping and can be used in your raised bed gardening. The optimum spacing for your purposes will depend on the size of the vegetables required. Onions, for example, when planted at a spacing of 225 mm can grow very large.

At 100mm spacings, on the other hand, individual bulbs will be a lot smaller, but total yields will be higher. Smaller bulbs will store for longer periods and are often more useful.

However, spacings between plants in raised bed gardening has to be practical. If large spaces are allowed the vegetables will never fill those spaces and this will be a waste of space. If planted too close together the plants will choke each other, and there will be little of the vegetable that is big enough to eat.

RAISED BED GARDEN: Sowing and Planting Guide for Intensive Beds

BROAD BEANS (tall) 150-225 mm

BROAD BEANS (dwarf) 225-300 mm

BEANS (bush) 225-300 mm

BEETROOT 75-100 mm

BRUSSEL SPROUTS 500-700 mm

CABBAGE (small) 250 mm

CABBAGE (large) 450-600 mm

CAULIFLOWER (small) 250 mm

CAULIFLOWER (large) 450-600 mm

CARROT 75-100 mm

CELERY 250 mm

CUCUMBER 600 mm

LEEK 75-225 mm

LETTUCE 225 mm

ONION (spring) 25 mm

ONION (keeping) 100-150 mm

PARSNIPS 75-150 mm

PEAS 75-100 mm

POTATOES (early) 225 mm

POTATOES (main crop) 300 mm

CORN 375 mm

TOMATOES (staked) 600 mm

TOMATOES (bush) 450 mm

For vegetables that are widely spaced inter-crop with fast growing vegetables such as radishes, spring onions, rocket and some lettuces. Check our page on companion planting to see which crops can be grown together. Early potatoes grown between rows of raspberries for example are not an ideal marriage.

RAISED BED GARDEN: Crop Rotation

Don't get tied into knots over crop rotation. Just make sure that you don't plant the same vegetable in the same bed consecutively.

The object of crop rotation is to avoid certain soil-borne diseases caused be eel worm, or fungus such as club-foot of brassicas. It also makes good use of organic fertilizers.

For example, a fertilizer of well-rotted poultry manure is high in nitrogen and ideal for leaf crops such as cabbage, lettuce etc. When followed by root crops, the remaining mineral salts should be adequate to grow healthy carrots, parsnips etc. Hence the light feeders such as roots, bulbs, legumes, tubers and small lettuces can follow call other crops which are classed as heavy feeders. See our page on growing carrots for in depth instructions and advice.

Knowing which vegetables belong to which family is important, because diseases are common to each member of the same family.

GROUP ONE:

Potato

Tomato

Capsicum

Eggplant

GROUP TWO:

Onion

Leek

Garlic

GROUP THREE:

Pumpkin

Marrow

Melon

Cucumber

GROUP FOUR:

Cabbage

Cauliflower

Brussel Sprouts

Broccoli

Swede

Radish

Mustard

Kohlrabi

GROUP FIVE:

Silver Beet

Swiss Chard

Red Beet

GROUP SIX:

Peas

Beans

Lupin

Clover

Lucerne

Legumes

GROUP SEVEN:

Carrot

Parsnip

Parsley

Legumes (Group Six) may not thrive when grown directly in the soil after alliums (Group Two) due to under composed root exudation. Legumes are unique in that they return to the soil more nitrogen that they use during their growth, however, edible crops are not good sources compared with clover and lucerne.

As you can see, as long as you have soil, drainage and suitable containers or boxes built out of handy material, you can build raised beds very successfully. Raised bed gardening is an ideal way of raising healthy vegetables without heavy digging or bending.