Start with what grows well in containers and shallow soil

Raised beds work best for vegetables, herbs, and shallow-rooted plants because you control the soil depth and quality from the start. Most raised beds are 12 inches deep, which is enough for lettuce, spinach, radishes, and herbs. If your bed is 18 inches or deeper, you can grow tomatoes, peppers, carrots, and beans. Root vegetables like beets and potatoes need at least 12 inches; deeper is better. The key is matching the plant's root depth to your bed's depth so roots don't hit the bottom and stop growing.

Before you buy seeds or seedlings, measure your bed's depth and check the seed packet or plant tag for the minimum soil depth required. A packet that says "12 inches minimum" will struggle in a shallower bed. Herbs like basil, parsley, and thyme are forgiving and grow in almost any depth, so they're a safe first choice if you're unsure.

Key Takeaways

  • Shallow beds (12 inches) work for lettuce, spinach, radishes, herbs, and green onions; deeper beds (18+ inches) support tomatoes, peppers, carrots, and root crops.
  • Check the seed packet or plant tag for minimum soil depth before planting, because roots that hit the bottom of the bed will stop growing and reduce your harvest.
  • Raised beds warm up faster in spring and cool down slower in fall, so you can plant cool-season crops earlier and later than in-ground gardens.
  • Herbs, lettuce, and leafy greens are the easiest plants to start with because they tolerate shallow soil and grow quickly from seed.
  • Plant tall crops like tomatoes and beans on the north side of the bed so they don't shade shorter plants on the south side.

Vegetables that thrive in shallow raised beds

Lettuce, spinach, arugula, and other leafy greens are the fastest and easiest crops for a raised bed. They need only 6 to 8 inches of soil, grow in 30 to 45 days from seed, and tolerate partial shade. You can plant them in early spring, harvest in late spring, then plant again in late summer for a fall crop. Radishes are even faster—ready in 25 to 30 days—and take up little space, so they're good for filling gaps between slower plants.

Green onions, peas, and bush beans also do well in shallow beds. Green onions need 6 inches and can be harvested in 60 days. Peas and beans need 8 to 10 inches and produce heavily in a small space. All three are good choices if you want something more substantial than salad greens but don't have room for sprawling vines.

Vegetables that need deeper soil

Tomatoes, peppers, eggplants, and cucumbers need at least 12 inches of soil, ideally 18 inches. Tomatoes especially benefit from deep soil because their roots go down 2 to 3 feet in ideal conditions; a 12-inch bed will work but won't give you the biggest harvest. Peppers are more compact and do fine in 12 inches. Cucumbers and summer squash sprawl across the surface but still need 12 inches below to support the plant.

Carrots, beets, parsnips, and potatoes are root crops that need at least 12 inches, and deeper is better. A carrot planted in 8 inches will fork or curl instead of growing straight. Potatoes especially benefit from 18 inches or more because you can mound soil over them as they grow, which increases your yield. If your bed is only 12 inches deep, stick to shorter varieties like 'Nantes' carrots or 'Fingerling' potatoes.

Herbs that grow almost anywhere

Basil, parsley, cilantro, chives, thyme, oregano, and sage all grow in 8 to 12 inches of soil and tolerate partial shade. Basil is the fastest—ready to harvest in 3 to 4 weeks—and produces all summer if you pinch off the flower buds. Parsley and cilantro are slower (60 to 70 days) but last longer and regrow after cutting. Thyme, oregano, and sage are perennials, meaning they come back year after year, so plant them once and harvest for years.

Herbs are ideal for the edges of a raised bed because you can reach them easily and they don't shade other plants. A single basil plant in the corner of a 4-by-8-foot bed will give you fresh leaves all season. If you're new to gardening, start with basil and parsley—both are nearly impossible to kill and grow fast enough to feel rewarding.

How to arrange plants by height and sunlight

Tall plants like tomatoes, peppers, and pole beans should go on the north side of the bed so they don't shade shorter plants on the south side. In the Northern Hemisphere, the sun moves from east to west and is highest in the south, so the south side gets the most light. Lettuce and spinach actually prefer afternoon shade in summer, so planting them on the south side of a tall tomato plant keeps them cooler and delays bolting (going to seed).

Space plants according to the seed packet. Tomatoes need 24 to 36 inches between plants; lettuce needs only 6 to 8 inches. Crowding plants saves space but reduces air flow, which can lead to mildew and disease. If you're unsure, follow the packet's spacing and thin seedlings if they come up too close together. The thinned seedlings are usually edible—baby lettuce and spinach are tender and mild.

Timing: when to plant each crop

Cool-season crops like lettuce, spinach, peas, and broccoli tolerate frost and grow best in spring and fall when temperatures are 50 to 70 degrees Fahrenheit. Plant them 2 to 4 weeks before your last spring frost, or 8 to 10 weeks before your first fall frost. Warm-season crops like tomatoes, peppers, beans, and squash need soil at least 60 degrees and air temperatures above 50 degrees at night. Plant them after your last frost date, usually when the soil has warmed in late spring.

Raised beds warm up 2 to 3 weeks earlier in spring than in-ground soil because they're exposed on all sides and absorb heat faster. This means you can plant warm-season crops earlier in a raised bed. In fall, raised beds also cool down more slowly, so you can plant cool-season crops later and harvest longer. Check your local frost dates online—search your city name plus "frost date"—to know when it's safe to plant.

Common mistakes to avoid

The most common mistake is planting too densely. A raised bed looks empty when you first plant it, so the temptation is to squeeze in extra seedlings. By mid-summer, crowded plants compete for water and nutrients, and poor air flow leads to powdery mildew and other diseases. Follow the spacing on the seed packet, even if it feels wasteful at first.

The second mistake is planting tall crops on the south side where they shade everything else. Tomatoes and pole beans need full sun anyway, so put them where they won't block light from shorter plants. The third mistake is planting warm-season crops too early. Tomato seeds rot in cold soil, and pepper seedlings sulk and stop growing if the soil is below 60 degrees. Wait until the soil has warmed—you can check with a soil thermometer, or just wait until nighttime temperatures stay above 50 degrees.

Frequently Asked Questions

Can I plant the same crop in the same raised bed every year?

Yes, but rotating crops prevents soil depletion and reduces pest and disease buildup. If you grew tomatoes this year, plant beans or lettuce next year, then tomatoes again the third year. Beans add nitrogen to the soil, which tomatoes need. If you must plant the same crop twice, refresh the top 4 inches of soil with compost between plantings.

How deep should my raised bed be for vegetables?

Twelve inches is the minimum for most vegetables. Leafy greens need only 6 to 8 inches. Root crops and tomatoes benefit from 18 inches or deeper. If your bed is only 12 inches, avoid long-rooted crops like parsnips and focus on lettuce, herbs, beans, and shallow-rooted peppers instead.

Can I plant flowers in a raised vegetable bed?

Yes. Marigolds, nasturtiums, and zinnias grow well alongside vegetables and attract pollinators. Marigolds also repel some pests. Plant them on the edges so they don't shade vegetables, and choose varieties that don't grow taller than your tomatoes or peppers.

What if my raised bed gets only 4 hours of sun?

Lettuce, spinach, arugula, parsley, and cilantro grow fine in 4 to 6 hours of sun. Tomatoes, peppers, and beans need at least 6 to 8 hours. If your bed is in partial shade, focus on leafy greens and herbs rather than fruiting crops.

Can I plant seeds directly in the raised bed or should I use seedlings?

Both work. Seeds are cheaper and fun to watch grow, but they take longer and need consistent moisture. Seedlings (small plants from a nursery) are ready to harvest weeks earlier. For a first raised bed, start with seedlings of tomatoes and peppers, and direct-seed lettuce, beans, and radishes—that mix gives you quick wins and longer-term crops.