Plan Ahead for Midsummer Vegetable Crop Rotations

24 May 2013, written by Barbara Pleasant

From spring to autumn, vegetable gardens undergo constant change. A big transformation takes place in midsummer when spring crops are ready to harvest, creating space for new plantings. But what should they be? What to plant after early potatoes? What to plant after peas?

These questions may seem premature, but not if you want to make the most of the next big round of planting opportunities. Whether you call it succession cropping or relay planting, you often will get the best results (and waste no precious growing season time) by having sturdy seedlings ready to plug in as soon as spent crops are cleared away. For example, if you start seeds of leeks, squash, kale or Brussels sprouts in the next few weeks, you can immediately pop them into prepared ground when space becomes available.

Leeks benefit from being started early in pots

Of course you will want to rotate plant families in order to alter nutritional demands on the soil and avoid the buildup of soil-borne diseases. And there is another factor to consider when planning midsummer vegetable crop rotations. Bits of root left in the soil after growing onion family crops including garlic, shallots and all type of onions can inhibit the growth of some legumes, but may be beneficial to leafy greens and tomato family crops – a little something to keep in mind.

What to Plant After Lettuce and other Leafy Greens?

The first crops to lose quality and bolt are leafy greens like lettuce, mustard, spinach, and rocket. Rapidly lengthening days encourage the plants to elongate and bloom, which quickly earns them a place in the compost heap. For most gardeners, the best vegetables to plant after lettuce are dwarf beans, which germinate fast in warm soil and produce heavily in late summer. Other good veggies to plant after lettuce include carrots, cucumbers, squash or a second sowing of basil to carry you through the summer. And, if you have always dreamed of growing Brussels sprouts, the site of your spring salad garden may be the perfect place.

What to Plant After Garlic or Onions?

Like leafy greens, garlic and onions mature in response to lengthening days, with the garlic bulbs ready to lift and cure in midsummer, followed by onions a few weeks later. Even before that, I have space to replant after winter onions and fall-planted leeks have made their way to the kitchen.

You have many options as you decide what to plant after garlic or onions, as long as you don’t choose an onion or a legume. In my climate, I can squeeze in a late crop of winter squash or fast-maturing pumpkins after garlic, but only if I have vigorous seedlings growing in containers, ready to plant as soon as the bed has been cultivated to incorporate a fresh helping of compost and balanced organic fertiliser. Swedes direct-seeded into a bed previously occupied by alliums works well in terms of time, too. In climates with long growing seasons, capsicum and tomatoes also are good candidates for planting after garlic or onions. In cooler climates, Chinese cabbage or pak choi may be the perfect choice.

What to Plant After Potatoes?

Late-maturing potatoes stay in the ground all summer, but early new potatoes are often out of the garden by July. Potatoes take up a lot of soil nutrients, but because most gardeners mulch their potatoes, there is often a gain in soil organic matter. When nutrients are replenished with a balanced organic fertiliser, a potato plot often makes a great place to grow cabbage family crops for fall like cabbage, collards or kale. Leeks or scallions are excellent choices, too, though you will need to start seeds now in order to have the seedlings you need in midsummer.

I often rotate my potato row into fall-planted garlic or onions, so rather than growing a food crop, I use the late summer shoulder season to grow a soil-building cover crop. One of my favourites (so far) is hulless oats interplanted with sunflowers – a lush and pretty combo for late summer into fall. Buckwheat makes a great late-season cover crop, too.

What to Plant after Peas?

Spring-sown peas stay productive all summer in cool climates, but in most areas they are done-for by the time summer gets into full swing. The most popular vegetable to plant after peas is cucumbers, which often can be trained up the same trellis used by the peas. Indeed, members of the squash family quickly make themselves at home in pea soil, and the same is true of root crops like carrots and parsnips. In areas where there is only a short snip of growing season left when the peas come out, leafy greens like lettuce and spinach make ideal replacements.

The best plans for midsummer vegetable crop rotations will vary from climate to climate and garden to garden. In addition to the relay planting ideas and techniques here, you can experiment with many other veggies that grow best in fall, like bulb fennel or broccoli. Just when you thought you were through starting seedlings, it’s time to start more. But if you want to keep your garden productive all season long, you have to keep planting.

By Barbara Pleasant