Start with soil depth and spacing for the vegetables you want

The depth of soil you need depends on what you are growing. Shallow-rooted crops like lettuce, spinach, and radishes need 6 to 8 inches of soil. Medium-rooted crops like beets, chard, and bush beans need 8 to 10 inches. Deep-rooted crops like tomatoes, peppers, carrots, and parsnips need 12 inches or more. If your raised bed is only 8 inches deep, you can still grow lettuce and spinach in it, but not carrots.

Before you plant, decide which vegetables go where based on how much space each one needs. A tomato plant needs about 2 feet in every direction. A pepper plant needs about 18 inches. Lettuce and spinach can grow 6 inches apart. Beans and peas can grow 4 to 6 inches apart. Crowding plants wastes space and invites disease because air cannot move between the leaves.

Draw a straightforward map on paper before you dig. Mark where each plant will sit. This takes five minutes and prevents you from planting too densely or running out of room halfway through.

Key Takeaways

  • Shallow-rooted crops like lettuce need 6 to 8 inches of soil, while deep-rooted crops like tomatoes need 12 inches or more.
  • Space plants according to their mature size—tomatoes need 2 feet in every direction, lettuce needs 6 inches—to prevent crowding and disease.
  • Plant seedlings at the same depth they were growing in their containers, with the soil line at or just above the top of the root ball.
  • Water when ready after planting and keep the soil consistently moist (not waterlogged) for the first two to three weeks while roots establish.
  • Mulch around plants with 2 to 3 inches of wood chips or straw to retain moisture and suppress weeds.

Prepare the soil and test its moisture before planting

Your raised bed should be filled with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts. If you filled it months ago, the soil has likely settled and compacted. Break up the top 6 to 8 inches with a garden fork or spade before planting. Remove any weeds, rocks, or debris.

Check the soil moisture by squeezing a handful. It should hold together loosely but crumble when you poke it. If it is soggy and stays in a tight ball, it is too wet—wait a few days or add more compost to improve drainage. If it is dust-dry and will not hold together at all, water it thoroughly and wait 24 hours before planting.

Wet soil is harder to work with and compacts easily, which damages the structure you need for roots to grow. Dry soil does not give seedlings the moisture they need to establish. Planting into soil that is damp but not wet gives you the best start.

Dig holes at the right depth for each seedling

The most common mistake is planting too deep. A seedling should sit at the same depth it was growing in its container—the soil line on the stem should be at or just barely above the top of the root ball. The exception is tomatoes: you can bury them deeper because they will grow roots along the buried stem, which makes them stronger. For tomatoes, bury the stem up to the first set of true leaves.

Dig a hole slightly wider than the root ball and just as deep. Gently remove the seedling from its container and loosen the roots with your fingers—do not tear them, but separate them enough that they can spread into the surrounding soil. Set the seedling in the hole so the top of the root ball is level with the soil surface. Fill the hole and press the soil gently around the stem.

If you are planting seeds directly (beans, peas, carrots, radishes, lettuce), follow the depth marked on the seed packet. Most seeds are planted at a depth equal to two or three times their width. A bean seed goes about 1 inch deep. A lettuce seed goes about a quarter inch deep. Plant several seeds in each spot and thin them out once they sprout if more than one comes up.

Water thoroughly right after planting

Water the bed deeply when ready after you finish planting. The goal is to settle the soil around the roots and eliminate air pockets. Water until it drains from the bottom of the bed—this usually takes several minutes of steady watering. Do not just sprinkle; soak.

For the next two to three weeks, keep the soil consistently moist but not waterlogged. Check it every day by pushing your finger an inch into the soil. If it feels dry, water. If it feels wet, wait. In hot weather, you may need to water every day. In cool or rainy weather, you may water only once or twice a week.

Once plants are established and growing visibly (usually three weeks in), you can water less frequently but more deeply. Deep watering encourages roots to grow down into the soil rather than staying near the surface.

Mulch to retain moisture and suppress weeds

After planting and watering, spread 2 to 3 inches of mulch around each plant. Wood chips, straw, or shredded leaves all work. Leave a 2-inch gap between the mulch and the stem so air can circulate and the stem stays dry. Mulch that touches the stem can trap moisture and cause rot.

Mulch keeps the soil cooler and moister, which reduces how often you need to water. It also blocks sunlight from reaching weed seeds, so fewer weeds sprout. As the mulch breaks down over the season, it adds organic matter to the soil, which improves its structure and water-holding capacity.

Refresh the mulch layer in mid-summer if it has broken down significantly. By fall, you can let the mulch stay and it will decompose over winter, enriching the bed for next year.

Harden off seedlings if they came from indoors

If you started seedlings indoors or bought them from a greenhouse, they are used to stable temperatures and filtered light. Moving them directly into the garden can shock them and stunt their growth. Harden them off by gradually exposing them to outdoor conditions over 7 to 10 days.

Start by setting them outside in a sheltered spot with dappled shade for 2 to 3 hours. The next day, leave them out for 4 to 5 hours. Gradually increase the time and the amount of direct sun they receive. By the end of the week, they should be able to stay outside all day and night. Then plant them in the bed.

If you skip this step, seedlings often wilt, turn purple, or stop growing for weeks while they adjust. The extra week of hardening off pays back in faster growth once they are in the ground.

Plant in the right season for each crop

Cool-season crops—lettuce, spinach, peas, broccoli, cabbage—grow best in spring and fall when temperatures are between 50 and 70 degrees Fahrenheit. Plant them 4 to 6 weeks before your first frost in fall, or as soon as the soil is workable in spring. They tolerate light frosts and actually taste better after a frost.

Warm-season crops—tomatoes, peppers, beans, squash, cucumbers—need soil and air temperatures above 60 degrees, ideally 70 degrees or warmer. Plant them after your last spring frost date. If you plant them too early into cold soil, the seeds rot and seedlings sit dormant instead of growing.

You can find your frost dates by searching "[your city] frost dates" or asking at a local garden center. Planting on the right schedule is one of the biggest factors in whether a crop succeeds or fails.

Frequently Asked Questions

Can I plant vegetables directly from seed in a raised bed?

Yes. Beans, peas, carrots, radishes, lettuce, and squash all grow well from seed planted directly in the bed. Follow the depth and spacing on the seed packet. Plant several seeds in each spot and thin them once they sprout if more than one comes up. Tomatoes and peppers are usually started indoors or bought as seedlings because they take too long to reach planting size from seed.

What if my raised bed is only 6 inches deep?

You can grow lettuce, spinach, radishes, and shallow-rooted greens in 6 inches of soil. You cannot grow tomatoes, peppers, or carrots. If you want to grow deeper-rooted crops, you will need to add more soil or build a deeper bed.

How often should I water after the first few weeks?

Once plants are established, water deeply once or twice a week depending on temperature and rainfall. Stick your finger 2 inches into the soil—if it feels dry, water. If it feels moist, wait. Raised beds drain faster than in-ground gardens, so they usually need more frequent watering in hot weather.

Can I plant vegetables close together to save space?

Crowding reduces air flow between plants, which invites fungal disease and pest problems. It also means each plant competes for water and nutrients, so they grow smaller and produce less. Space them according to their mature size. You will get more food from a properly spaced bed than from an overcrowded one.

What should I do if a seedling looks wilted after I plant it?

Check the soil moisture first—it may be too dry. Water deeply if the soil is dry. If the soil is moist and the plant is still wilted, it may be sunburned or shocked from hardening off too fast. Move it to partial shade for a few days and keep the soil consistently moist. Most seedlings recover within a week.