Everyone who grows vegetables, particularly the home gardener with limited space, looks for ways to get the biggest harvest possible from every bit of space. Succession planting is the most effective and efficient method of doing this. When a crop is harvested, it’s immediately replaced with another crop. In most of the United States and Canada, this means you can grow two or more crops in the same space each growing season.
Sow in stages
The strategy behind succession planting is to sow a vegetable every few weeks, rather than all at once, to stagger the harvest and maintain continuous production. Bush beans, for example, can be planted every two or three weeks to keep them in production until frost. Many root crops and salad greens can be planted every few weeks in the spring, then again in the fall as cool weather returns.
There are, however, variations on this basic theme that can enhance garden production, particularly if you plant early, midseason, and late varieties of the same vegetable. In spring, plant cool-season varieties that mature in about 50 days. Follow with a main crop that tolerates summer heat, and end the growing season with a fast-maturing, frost-tolerant variety.
Lettuce is a perfect example. With proper planning and selection, you can enjoy fresh lettuce in your salad from early spring until late fall, well after the first frost in your area. In spring, plant leaf lettuce every two or three weeks, using a different variety for each planting. As warm weather arrives, start filling empty spaces with heat-tolerant varieties such as ‘Royal Oak Leaf’ or ‘Green Ice’.
Meanwhile, start some seedlings indoors in flats, so you can replace harvested lettuce with fresh seedlings throughout the summer. In late August, plant transplants of late varieties like ‘Brune d’Hiver’ or ‘Winter Density’, which will produce well into the winter if protected under floating row covers.
Choose vegetables with different maturity dates
For slow-growing vegetables—including tomatoes, peppers, and most cole crops—plant varieties with different maturity dates at the same time. For example, early varieties of cabbage mature in about 55 days, midseason varieties in 80 days, and late varieties in 100 or more days. By planting them simultaneously in spring, you can harvest cabbage well into the fall.
Although it requires more planning, consider planting and harvesting different vegetables in the same space throughout the season. Peas will not tolerate hot summer temperatures, so in early spring plant early varieties like ‘Alaska’ and ‘Early Freezer 680’, along with midseason varieties like ‘Green Arrow’ and ‘Top Pod’. Your harvest will begin in late spring with the early peas, and continue with the midseason peas until the heat of summer.
As you harvest the peas, replace them with a crop of quick-maturing bush beans like ‘Venture’ or ‘Top Crop’. Then, in late summer, after the beans are harvested, you may have time to plant late peas like ‘Wando’ or ‘Alderman’ for a fall crop. If frost comes early in your area, plant a late variety of spinach or lettuce instead of peas.
Group vegetables according to harvest time. Plant early-maturing and late-maturing crops in different areas for easier planting and harvesting. Parsnips, salsify, and celeriac require up to 120 days to mature, so they don’t make good succession crops. Likewise, perennial crops like asparagus, rhubarb, chives, and horseradish are not candidates for succession planting. Plant these in the back of the garden where they won’t be disturbed. Save the open, more accessible areas of your garden for your succession crops.
Calculate the days to maturity of each variety you plan to use. When considering maturity times, remember they’re based on ideal conditions. Always allow a two-week leeway. List the categories of vegetables you intend to plant, then search seed catalogs for early, midseason, and late varieties of each veggie. As a rule of thumb, select quick-maturing varieties whenever possible.
Factor in the expected frost dates in your area. As you plan your successions, use the last expected frost date in the spring and the first expected frost date in the fall as calendar guides, then plan your sowings according to the days to maturity of the varieties you have in mind.
Familiarize yourself with the growing characteristics of the crops you select and decide which ones would work best in your succession planting plan. For example, lettuce will not germinate in hot August soil, so you’ll have to start seedlings indoors and transplant them in late August or September for a fall crop. Most bush beans will not germinate in cool soil, but ‘Royal Burgundy’ tolerates cool soil better than other varieties and can be planted soon after the last frost in the spring.
Consider crop rotation as you plan your successions. Try not to plant members of the same family in the same space for at least two years. For example, to prevent the spread of soil-borne diseases like clubroot, don’t plant cole crops in the same space the following year. Follow heavy feeders like broccoli and sweet corn with beans or peas, which replenish the nitrogen in the soil.
Deviate from your master plan as opportunities arise. You’re likely to find unexpected extra space and “holes” in the garden, perfect for tucking in extra lettuce and broccoli seedlings.
This process can become complicated when you’re planning succession crops for a dozen or more vegetables with various maturation periods, but the benefits in production are well worth the trouble.
How to read seed catalogs
In January and February, when you’re perusing that stack of seed catalogs and planning next year’s garden, keep succession planting in mind as you choose vegetable varieties.
First, look for days to maturity. For example, ‘White Lady’ turnips (an “early” cultivar) reach maturity in about 35 days; compare this variety to ‘White Knight’, which matures in 75 days. Note also that the days to maturity are from the time of transplanting into the garden, not from the time of starting your seeds indoors.
Also consider frost and heat tolerance. For very early and very late crops, select varieties that can withstand frost in the spring and fall. Likewise, for extreme summer conditions, select varieties that can withstand heat and drought. For example, many lettuce varieties will bolt when the summer heat threatens, but ‘Royal Oak Leaf’ and ‘Buttercrunch’ will remain succulent long after early varieties have gone to seed.
Study the seed catalogs and make your decisions wisely. Every year, try new varieties, looking for even more efficient use of your garden space. Don’t be afraid to experiment!
Succession planting in a “grid garden”
If you use a square-foot or other grid system in your garden, succession planting is a breeze. Before ordering seeds, map your garden on graph paper. Lay out each bed in square-foot or other size blocks, and determine which vegetable varieties you’ll use in each space.
Schedule your plantings according to each variety’s days to maturity and hardiness. When the growing season begins, you’ll be filling each space in succession according to this master plan.
It’s amazing how many vegetables you can get from just one square foot. For example, plant ‘French Breakfast’ radishes as early as possible in spring. After harvesting radishes, plant a fast-maturing lettuce like ‘Green Ice’, which you’ll harvest in early summer—just in time to sow an early-maturing cultivar of bush beans such as ‘Provider’. After harvesting the beans in late summer or early autumn, you’ll still have time to plant a late spinach variety like ‘Cold Resistant Savoy’.
So, in one square foot of space, you could grow radishes, lettuce, beans, and spinach—all in one season. Imagine what’s possible for your entire garden with the right planning, timing, and selection of varieties!
Weldon Burge is a garden writer in Newark, Delaware.