The following is an excerpt from Backyard Bounty: The Complete Guide to Year-Round Organic Gardening in the Pacific Northwest by Linda Gilkeson (New Society, 2011). The excerpt is from Chapter 2: Planning a Productive Garden.
Land is expensive, and few people can afford the large lots or rural properties that make it possible to have a large garden. However, the point of this book is that you don’t have to have much space to grow a surprising amount of food, especially if you adopt some of the intensive methods described below. There are several ways to increase productivity so that your garden is full of food most months of the year:
Grow more plants in the same space:
• In fertile soil you can grow vegetables closer than the spacing recommended on the seed package — sometimes much closer. A bonus is that densely planted crops help control weeds by shading them out.
• Grow vegetables in beds, rather than spaced out in rows: you waste much less space on unproductive rows and have a smaller area to weed.
• Within a bed, set individual plants in a staggered pattern, which allows closer spacing while giving each plant room for its roots.
In the first years of a new garden, the soil might not be fertile enough to plant too densely, so keep an eye on how your plants look. You might need to give them a dose of liquid fertilizer a few times over a summer to keep them growing well. Thin the plants if it looks like they are struggling. Over time, as you continue to add compost and other amendments, your soil will improve and you can grow plants closer together.
Take advantage of vertical space. Crops with sprawling vines take up more space on the ground than their roots do in the soil below. Trellising them off the ground opens up more space for planting:
• Stake up tomatoes, cucumbers and melons or train the vines on a trellis. (You can make slings of cloth to support melons so they don’t pull the vines off the trellis.)
• Grow pole beans instead of bush beans; they produce more over a longer season in the same amount of space.
• Use the space along fences and walls to grow plants you can train vertically, such as beans, grapes and kiwi vines.
As well as using vertical space, sometimes you can use nongarden space to accommodate plants temporarily. For example, you can plant winter squash (most are notorious ramblers) where you can direct the vines between corn plants, under fruit trees, over a patio or other non-garden space.
Avoid wasting space on unproductive plants: Gardeners soon learn that a small patch of lettuce can provide a lot of salad, and that radishes shoot past their prime in days. To avoid wasting space on crops you won’t use, sow smaller amounts of the quick-maturing vegetables at 2–4 week intervals. That way you don’t have too much of any one vegetable to deal with at one time, and you can enjoy a longer harvest of vegetables in prime condition. The coastal growing season is quite long for crops that thrive in cool conditions, making second, third, or even fourth plantings of peas, lettuce and cauliflower possible.
Keep trying out different planting dates for your favorite vegetables: you might discover how to enjoy them longer. It was only after years of sowing peas in early spring (having given up on them as a fall crop), that I discovered how well they do when sown in mid-June in the shady end of my garden. I now enjoy peas through October!
Minimize the time garden space stands empty: A Dutch grower once told me “never leave a space empty more than a day.” In my coastal climate, this is quite possible. Many vegetables for winter harvests can be sown immediately after spring crops are finished. For example, the earliest sowings of peas, radishes, lettuce and other salad greens are usually exhausted by July. Garlic (planted the fall before) and onions (from onion sets) are also harvested by mid-July. So July is a perfect time to sow hardy greens, such as kales, Komatsuna and leaf beet, which will occupy the garden bed until the end of May the following year.
Be ready to fill gaps as they arise by keeping a small area in one of your beds as a seedling nursery. Crops such as cauliflower or corn, for example, leave empty spaces in the bed as they are harvested one by one. You can fill these spaces immediately with seedlings of lettuce, kale, Chinese cabbage, leaf beet and other plants if you already have them started in a nursery bed.
You can also use the seedling nursery to make a winter crop planting schedule work when crops that should be finished are lingering later than expected. A cool summer can jam up the schedule for hardy vegetables that should be sown in July. But you can start your winter crops in a seedling bed (or in flats) and move them to growing beds when space opens up. It depends on the crop, but most transplants can be set out 3–4 weeks later than they would be seeded directly. This buys you an extra month to allow a crop still occupying a bed to mature. Or, because local nurseries are beginning to carry winter crop seedlings in the summer, you can skip sowing seeds altogether and just buy transplants to fill gaps as needed.
Interplanting: Some combinations of vegetables can share the same garden space. Plants that occupy different root zones or mature at different times make good partners. For example, lettuce, which has short roots and grows quickly, can be tucked in around a variety of larger, deep-rooted vegetables. The lettuce is harvested and gone by the time the other crop needs the space. I never plant lettuce separately anymore because there are so many places to fit it in among other crops.
One of my favorite combinations is planting lettuce between Brussels sprouts, which, because they grow quite large, need to be widely spaced. The same goes for winter cauliflower and winter broccoli, which occupy garden space in beds from mid-June to the following spring. When they are still small, interplant them with lettuce (or other salad greens). Or, plant cauliflower and broccoli between cucumbers or melons. The low vines shade the soil, which is good for the cauliflower and broccoli roots in the summer.
Some of my other favorite combinations:
• Leafy greens (Swiss chard, Chinese cabbage) can be planted in alternating rows between root crops (carrots, beets).
• Green sprouting broccoli (a very large, productive summer broccoli) can be interplanted with early cauliflowers, which are harvested by the time the broccoli expands to fill the space.
• Radishes sown sparsely in carrot beds break the soil for the carrots and are half grown by the time the carrots germinate.
• Lettuce grows well between newly planted strawberries or asparagus.
• Onion sets planted along the edges of garden beds mature in mid- to late July and leave the space to the other crop.
Whatever the combinations you try, be alert to how the plants are growing. Thin or remove the interplanted crop if the main crop is struggling or supplement with a feeding of liquid fertilizer as needed.
Underplanting: Also called “relay cropping,” underplanting is starting the next crop in a bed before the previous crop is finished. It works particularly well for fast-growing greens (corn salad, lettuce, spinach, leaf mustard) which can be sown underneath warmseason plants that will be finished in the fall.
For example, in late August, I lift up winter squash vines and broadcast corn salad and lettuce seeds over the soil. The seedlings grow well in the shade of the vines and are a good size by the time cold weather puts an end to the squash.
You can underplant squash, cucumbers, melons, tomatoes and peppers. To avoid disturbing the new crop, cut the spent plants at the soil line rather than pulling them out.