Small Garden, Big Harvest
By Chris Colby
Vegetable gardeners’ big dreams can sometimes be squashed by small garden spaces. Their visions, inspired by myriad seed catalogs, collide with the actual dimensions of their plots. With a few simple tricks, though, you can maximize the productivity of even the smallest vegetable patch, and harvest the plethora of produce you’ve always imagined.
Pick Your Produce
Some vegetables make more efficient use of space than others. For example, a cherry tomato plant — taking up perhaps a 3-by-3-foot space — yields about as much usable vegetable matter as a pumpkin plant that takes up a 12-by-12-foot plot. Years ago, the National Garden Bureau (NGB) compiled a list of the most efficient vegetables to grow. Its ratings take into account the productivity of each plant per square foot, the value of the produce, and the time required to grow it. Not every vegetable is on the list; zucchini, a legend in garden productivity, isn’t specifically mentioned. Likewise, it doesn’t include herbs. Although the list is incomplete, it’s still a good place to start when you’re considering what to grow. (See “The Most Valuable Vegetables” below.)
However, efficiency isn’t your only — or even overriding — consideration when choosing which vegetables to plant. Every gardener has a favorite crop, and some high-yielding veggies may go unused if planted. (Personally, I’d rather have a couple of melons than an endless supply of turnips.)
Image Carolyn Lang
So, to plan a productive garden, I suggest the following approach: Write a wish list of every plant you’d grow if you had the space. Then, rank the plants according to your desire to grow them. Compare the NGB list to your list of desired vegetables, and decide how to weigh efficiency against the vegetables you prefer. Check seed catalogs for cultivars that are noted for being productive; the difference between a modern hybrid and an old-school heirloom can be startling. Next, start at the top of your list and decide the minimum number of plants you’ll need to deliver enough vegetables for your household. Estimate the space (in square feet) required for that number of plants. And finally, measure the total square footage of your garden space to see what’ll fit.
After deciding what to plant, you must decide how to plant. Say you’re growing a bush bean cultivar that, when fully grown, has a diameter of 2 feet. You plant this bush bean in the center of a 2-by-2-foot raised bed. It won’t be shaded by any other plants, and its roots won’t interfere with those of another plant. For comparison, let’s say you have an identically sized raised bed, and you plant two plants in it along the diagonal. In this case, the branches of the two plants will grow into each other, partially shading each other, and the roots will grow together in the area between the plants. Finally, say you have an identical third bed, and you plant three plants there in a triangular pattern, maximizing the amount of space between each of the plants. These will be more cramped both aboveground and belowground. Often, when the branches of two plants grow together, moisture can be trapped between the leaves. On the other hand, the closely grown plants will shade the ground and suppress weeds. Which raised bed will be the most efficient producer of produce?
Say that the lone bush bean in the first planter yields 60 ounces of beans. In the case of the second planter with two bushes, that spacing will be more efficient than the first planter only if each plant yields over 30 ounces of beans. In the planter with three bush beans, it’ll only be more efficient than the lone plant if each plant yields more than 20 ounces of beans. The message is that to maximize the efficiency of a garden plot, the productivity of individual plants can be sacrificed, up to a point.
Perhaps you prefer to plant in rows. The seed packets of vegetables frequently give row spacing. Typically, plants in rows are tightly spaced, with a relatively large space between rows to create a walkway for the gardener. However, planting a garden with alternating rows of plants and walkways isn’t a very efficient use of space. In a garden planted this way, over half the available space may be unproductive, bare soil that will need to be weeded.
An improvement on traditional plant spacing would be to plant two rows next to each other, with the spacing between the two rows equal to the spacing within the rows, leaving the distance between and within the double rows the same. This simple adjustment would nearly double the amount of plants in the garden, but the plants in the double rows would be cramped on three sides as opposed to just two. However, you could loosen the within-row spacing a bit to ease crowding. With this arrangement, each pathway would allow you to access at least half the plants in each surrounding double row.
For example, a common spacing recommendation for many bush bean cultivars is 6 inches within rows and 2 feet between rows. To follow the double row planting model, you’d start by doubling the spacing between plants in the row and also applying that measurement to the spacing between the rows. This would eliminate one walkway without removing any plants.
Further developing this idea, you could consider planting in triple rows. The outer two rows would have the same degree of crowding as in a double row. The middle row would be cramped on all sides, unless you adjusted the spacing between plants in that row. And, if the vegetable in question was small enough, you could still bend over and have access to the middle row. With this approach, you could shrink a garden with nine single rows and eight walkways into three triple rows and two walkways. This would free up a lot of space in your plot for planting more vegetables. For example, if you increased the spacing between bush beans in the middle row by 25 percent, you could still have a good number of plants while eliminating a walkway.
Finally, a walkway doesn’t need to extend the full distance of a row. You could plant a double or triple row of vegetables running down the center of the garden, perpendicular to the other rows. Or, you could plant single, relatively large vegetables in the center of the walkways.
Experienced gardeners will have some idea of the size of the full-grown plants. If you’re just starting out, gardening books or seed catalogs may give the dimensions of a full-grown plant. Use the recommendations as a starting point, and adjust the spacing as needed to find that sweet spot.
To get the most from a vegetable garden, your soil needs to be suitable. If you’ve successfully grown a garden for many years in the same location, simply spread some new compost and aerate the soil with a broadfork. If you’re planting in a new or underperforming plot, however, you should amend the soil so it’s rich and aerated. If it’s heavy clay soil, stir in some sand, perlite, or vermiculite to keep it from clumping. You may need a rototiller for this. If your soil is deficient in organic material, stir in topsoil, peat, or compost — or a mixture of the three — to properly amend it. You can even add potting soil to heavy, clumping soils. Aim to make a deep bed that’s well-aerated and well-drained. Once you’ve achieved this, don’t rototill or dig (except for planting) after the first year; this will benefit the soil ecosystem.
If you live in an area where the depth of topsoil is minimal, raised beds are a great option. Rototill as deep as you can where you plan on putting the raised bed. A mix of quality topsoil and peat, with a little compost added, would make an optimal garden bed.
To get the best harvest, you’ll need to fertilize your garden properly. Remember: More isn’t always better. For starters, most vegetables are grown for their fruits, and adding more fertilizer doesn’t increase yields. In fact, too much nitrogen will cause the plants to focus on growing longer stems and more leaves rather than producing fruit. Also, if you followed the planting directions on Page 18, your garden will already be crowded. You don’t want to give the plants so much fertilizer that they grow too big. You want them to be full-sized, green, and healthy, but not “supercharged.”
Your best bet is to frequently apply small amounts of liquid fertilizer. Start by looking on your fertilizer for an amount recommended per square foot of garden for a given time period. For example, it might instruct you to use 6 cups per 100 square feet every two months. Halve this amount of fertilizer, and break the additions into weekly allotments. In this example, you’d use 3 cups of fertilizer per 100 square feet. These 3 cups would be broken down into eight 3⁄8-cup additions, with one addition used every week for eight weeks.
Start using this fertilization program, but keep a close watch on your plants. Increase the amount of fertilizer if the plants start yellowing; decrease if they turn dark green or start to bolt. Unless they’re yellowing, skip fertilizer additions from when the plants start to flower through when they set fruit. Remember that plants get most of what they need from the sun, not the soil. (You could switch to a fertilizer with phosphorous, potassium, and no nitrogen, but go easy — large phosphorous and potassium additions don’t lead to more or larger fruits.)
Each day, far above your garden, the sun arcs across the sky in such a way that shadows fall in a northerly direction. So, to make the most of the sunlight on your plot, arrange your plants so that the shortest — which cast the smallest shadows — are on the south side of the garden. The largest plants should be placed on the northern edge of the garden, so their shadows fall outside the plot. If you plant your double or triple rows in an east-west orientation, plant the taller types in the northern row. If a plant can be grown on a trellis, place it on the northern side of the garden.
Arranging your garden so all plants catch the sun matters most later in the season. In spring, the seedlings will be too small to shade each other. In summer, the sun will be nearly overhead around noon, and all plants will get lots of sunlight throughout the middle of the day. But in fall, with the sun low in the southern sky, shadows from fully grown plants can have a major effect on neighboring plants.
Thinking horizontally, downward, and upward are important, but there’s another dimension we haven’t yet discussed: time. If you can grow two crops in one part of your garden over one season, you’ll have doubled that plot’s productivity. Some vegetables, such as green beans, mature quickly, and in most parts of the country, you could plant a second batch. In addition, you can extend your gardening season. If you plant seeds indoors at least 3 to 4 weeks before your average last frost date in spring, you can get a jump-start on your growing. Likewise, building or buying some simple cloches — or even heavy agricultural netting — can protect plants from cold weather and light freezes. This can extend the growing period into early winter.
To plan the perfect garden, sketch competing garden layouts. Drawing scale representations of your plots on graph paper is an easy way to visualize your garden, but there are also garden-planning software packages and apps to help. Alternatively, start planting seeds or seedlings, and simply stop when you run out of space. Either way, you can pack a lot more into your garden if you abandon standard spacing guidelines, tend your soil, and tighten things up year to year. You never know how much you can grow!
The Most Valuable Vegetables
Compiled by the National Garden Bureau, the following ranking of various garden vegetables on a scale of 1 to 10, with 10 being the most productive, is based on their yield per square foot, average value per pound, and time required to grow. (Note: Individual cultivars may perform better or worse than these numbers indicate.)
- 9.0 Staked tomatoes
- 8.2 Bunching onions
- 7.4 Leaf lettuces
- 7.4 Turnips (greens and roots)
- 7.2 Summer squash
- 6.9 Bulb onions
- 6.9 Peas (with edible pods)
- 6.8 Pole beans
- 6.6 Beets (greens and roots)
- 6.5 Bush beans
- 6.5 Carrots
- 6.5 Cucumbers
- 6.4 Sweet peppers
- 6.3 Broccoli
- 6.3 Swiss chard
- 6.3 Kohlrabi
- 6.2 Mustard greens
- 6.2 Spinach
- 6.1 Lima beans (pole)
- 6.1 Radishes
- 6.0 Cabbages
- 5.9 Leeks
- 5.6 Collards
- 5.3 Cauliflower
- 5.3 Eggplant
- 5.2 English peas
- 4.3 Brussels sprouts
- 4.3 Celery
- 3.8 Melons
- 3.8 Winter squash
- 1.9 Pumpkins
Chris Colby is an avid gardener who lives in Bastrop, Texas, with his wife and their cats. He has a doctorate in biology and writes frequently for Grit’s sister magazines Fermentation and Mother Earth Gardener.
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