The best vegetables to grow in raised garden beds
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Every year during the strawberry harvest, I daydream of growing strawberries in a long, narrow raised bed (tabletop height, so I don’t have to crouch, crawl, and squat to pick the berries, which is quite tedious). But a raised bed for my sizable strawberry patch would be a considerable undertaking and expense. Plus, I would need not just one but two beds to ensure a seamless harvest.
Unlike me, many gardeners do go through the effort of creating raised beds. Easy access, whether for ergonomics or limited mobility, is often the main reason, but it’s not the only one. If your yard has poor soil, such as clay soil with insufficient drainage, or it gets salt runoff from a nearby road or walkway, raised beds filled with clean, healthy soil are the only way to grow vegetables. Likewise, in an urban setting, raised beds are often your only option to have a vegetable garden. You could also decide their visual appeal alone is a good enough reason to grow vegetables in them. Each time I see a photo of a vegetable garden with some creative, nifty design, with walkways between the neat and tidy raised beds, I turn green with envy and admiration.
As for the types of vegetables you can grow in raised beds, you have plenty of choices, as long as you keep a few important criteria in mind.
Anticipate the size and spread
How wide and tall a plant grows is a critical factor when selecting the best vegetables for raised beds. By August, your 6-inch tomato seedlings will have become at least 4-foot-tall plants with lush, dense foliage — despite your best efforts to tame them by trellising them or growing them in a tomato cage. Overcrowding a raised bed will always backfire. Poor air circulation fosters plant disease, and wet conditions will only make things worse.
Keep in mind what lies beneath
The plant parts that you don’t see — the roots — have equally important space requirements belowground. When roots are competing for space, water, or nutrients, the plants become stunted and won’t produce a good crop. Fewer plants, correctly spaced, will give you better and healthier yields than an overstuffed raised bed.
The depth and size of vegetable roots varies. Generally, heat-loving vegetables have deeper, more extensive root systems than cool-weather spring and fall crops, because their roots need to spread farther and deeper to reach water. Pumpkins, winter squash, and watermelons have deep roots that go down 24 to 36 inches or more. Tomatoes, artichokes, okra, and sweet potatoes also have deep roots. Root vegetables — radishes, carrots, turnips, onions, shallots, garlic — grow best in loose, partially sandy soil, which makes them ideal candidates for raised beds, where the soil is usually much less compacted in the absence of foot traffic.
Pick compact varieties
The vines of a single zucchini or butternut squash can easily overgrow your entire raised bed. If you want to grow summer or winter squashes, melons, watermelons, or cucumbers, choose compact, non-vining varieties, such as bush-type summer and winter squashes. Cucumbers can also be grown on a trellis to save space. For tomatoes, go for patio tomatoes such as Sprite and Tumbling Tom — bush-type, determinate tomatoes work better in small spaces than indeterminate tomatoes.
If you want to grow beans, and your raised beds are taller than the common 10- to 12-inch height, choose bush beans instead of tall pole beans, or else you might need a ladder to pick them.
Prioritize veggies that cannot find another home
Since raised bed space is limited (prime) real estate, prioritize what you plant in them, giving preference to vegetables that could use the easy access that raised beds provide. For instance, herbs — both annuals such as cilantro and basil, and perennials such as rosemary and sage — also grow very well in containers or small pots that you can place on tiered plant stands for easy access. Herbs, therefore, don’t necessarily need to take up valuable space in a raised bed.
Consider the sun exposure
While you can grow tall vegetables such as corn in raised beds, they should not cast shade on other crops unless it is intentional, for example, when you actually want the corn to protect tender lettuce from the hot summer sun. Always familiarize yourself with the growing conditions of the crop (all spelled out on the seed package or the plant label) to see if it fits with the other plants in your raised bed.
Select vegetables that need warm soil
Raised beds also work well for those vegetables that require a certain minimum soil temperature for the seeds to germinate, or for young seedlings to grow. Beans, eggplant, melons, watermelons, okra, peppers, pumpkin, and squash all need a minimum soil temperature of 60°F (15°C) for seed germination. Because raised beds are exposed to air and sunlight on all four sides, the soil inside them warms up faster than garden soil. In the spring, raised beds work as season extenders, allowing you to plant earlier than in garden beds.
In the summer heat, however, the fact that the soil heats up faster and gets hotter than garden soil can also work against you, as soil in raised beds dries out quicker, and thus needs more watering than garden soil. Mulching can help counter this to a certain extent, but a raised bed in full sun still gets baked.
For that very reason, in hot, arid climates, you’ll fin the opposite of raised beds: sunken beds, which improve water retention and evaporation, and keep the soil cooler.
For that very reason, in hot, arid climates, there is the opposite of raised beds: sunken beds, which improve water retention and evaporation, and keep the soil cooler.
Crop rotation rules
A key rule in vegetable gardening is to never grow crops of the same plant family in the same location two years in a row, to cut down on plant diseases and soil depletion. That can be challenging for small, raised beds, but it is important that you keep good track of what you plant where and consult your records the following year to rotate the crop families.
If it is at all possible, every gardening season, dedicate one raised bed exclusively to one plant family. For example, one bed for the nightshades (tomatoes, eggplants, peppers), a second for the cucurbits (summer and winter squash, cucumbers, melons), and a third for brassicas such as kale, radishes, arugula, and cabbages. Organizing raised bed frames by plant family makes crop rotation much easier to track.
If you don’t have enough raised beds to keep the crop families separately, it might be better to take the less-is-more approach: Grow vegetables from fewer crop families and increase your chances of a healthy, plentiful harvest.