Crop rotation in a home vegetable garden, and why it works

You've got a veggie patch going, which is the hard part done. Then you notice this year's tomatoes aren't a patch on last year's, in the same bed, with the same care, and you can't work out what changed. Nine times out of ten the answer is that nothing changed, and that's the problem.

What crop rotation is

It's simply not planting the same vegetable, or anything closely related to it, in the same spot season after season. Plants take different things out of the soil, and growing the same one in one place strips the same nutrients over and over. On top of that, the pests and diseases that like that plant settle in and wait, because you keep bringing dinner back to the same address.

Moving things around breaks both cycles at once. It's free, it takes about ten minutes of planning a year, and it's the single best thing a home gardener can do for a tired bed.

How to do it without overthinking it

• Sort your veggies into families. Tomatoes, capsicums, eggplants and potatoes are all nightshades. Lettuce, broccoli, cauliflower and cabbage are brassicas. Pumpkin, zucchini and cucumber are cucurbits. Write the families down once and you're set.
• Think about what they eat. Heavy feeders like tomatoes and pumpkins strip a bed. Follow them with something light, like leafy greens, or with a legume that puts nitrogen back.
• Move the family, not the plant. Shifting tomatoes but planting capsicums where they were achieves nothing, because they share the same pests and the same diseases.

What it does for the soil

Beans and peas fix nitrogen out of the air into the soil through their roots, so a bed that grew legumes is in better shape than it was before you planted them. Put them in where the corn or the cucumbers were and you're rebuilding rather than just resting the ground.

Root crops do something different again. Carrots and parsnips break up the soil as they grow and open it out, which suits whatever goes in after them.

A four year plan that fits a backyard

1. Year one. Heavy feeders. Tomatoes, capsicums, pumpkin, zucchini. Feed the bed well before they go in.
2. Year two. Legumes. Beans and peas, to put nitrogen back into what the heavy feeders took out.
3. Year three. Root crops. Carrots, parsnips, onions. They don't need much and they'll open the soil up.
4. Year four. Leafy greens, or a green manure crop dug in. Then back to year one.

If you've got four beds you can run all four at once and rotate them around the circle each year. If you've got one bed, run the same order down the length of it in strips and shift the strips along.

Not much room to rotate

A small patch still rotates, it just does it in smaller steps. Use pots and grow bags for one or two crops each season and you've effectively created another bed you can move anywhere. Lettuce, herbs and dwarf beans all do fine in a pot, which frees the ground up for the things that genuinely need it.

The pest side of it

A lot of garden pests and soil diseases overwinter in the ground right where they fed. Move the crop and they emerge in spring next to something they can't eat. That is most of what rotation buys you on the pest front, and it costs nothing and sprays nothing.

Two habits that make it work

• Write it down. You will not remember what was in the back bed two seasons ago. A notebook in the shed, or a photo on your phone at the end of each planting, is enough.
• Feed between crops. Compost or an organic fertiliser dug in at the start of each planting keeps the bed ahead rather than slowly behind.

Shop related products

• D.T Brown Tomato Red Cherry. A heavy cropper, and a heavy feeder, so it starts the cycle.
• D.T Brown Carrot All Season. The root crop for year three, and it opens the soil up.
• D.T Brown Lettuce All Year. A light feeder, hardy, and it will crop for most of the year.
• Neutrog Bounce Back 20kg. Certified organic pellets for feeding the bed between crops.

Did you know we also stock loose bean and pea seed in the shop, including dwarf beans, climbing beans, broad beans and snow peas, plus bamboo stakes and trellis for the climbers. They're not on the website, so give us a ring on (08) 8536 4333 to check what's on the shelf.

The rest of the seed and fertiliser range is in the garden centre, and if you sketch your beds on the back of an envelope we'll help you work the rotation out.

More from the garden

• 7 mistakes to avoid in a new vegetable garden
• What soil microbes actually do in your garden
• How to make compost at home without it going wrong

Crop rotation is the least glamorous thing in gardening and one of the few that works for free. Ask me in the shop, I'm usually there.

Cheers,
Candeece