Start with soil depth and spacing before you plant anything

Most vegetables need 8 to 12 inches of soil to root properly, though some need more. Tomatoes, peppers, and squash want 12 inches minimum. Lettuce, spinach, and radishes do fine in 6 to 8 inches. Before you plant, measure your bed's depth and decide what will actually fit — a shallow bed limits your options.

Spacing matters as much as depth. Crowded plants compete for water and nutrients, and poor air flow invites disease. A tomato plant needs 24 to 36 inches between it and the next one. Lettuce needs 6 to 8 inches. Carrots need 2 to 3 inches. Check the seed packet or plant label for the exact distance — it is always there, and it is always worth following.

The simplest approach is to sketch your bed on paper before planting. Mark where each plant goes. This takes five minutes and saves you from pulling up half-grown plants later because they are too close.

Key Takeaways

  • Fill your raised bed with soil that matches the depth your vegetables need — most want 8 to 12 inches, but check the seed packet for your specific plants.
  • Space plants according to their mature size, not their current size, using the distance listed on the seed packet or plant label.
  • Plant seeds or transplants at the depth marked on the packet, usually with the soil line at the same spot where the seed was buried or where the stem meets the roots.
  • Water when ready after planting and keep the soil consistently moist for the first two to three weeks while roots establish.
  • Plant cool-season crops like lettuce and peas in early spring or late summer; plant warm-season crops like tomatoes and peppers after your last frost date.

Prepare the soil and add amendments before planting day

Raised beds drain faster than ground soil, so they dry out quicker. Mix in compost or aged manure — about one-third of your total soil volume — to help it hold moisture and add nutrients. If your bed is brand new, fill it completely and water it well a day or two before planting. This settles the soil and lets you see where it sinks.

Test your soil's pH if you can. Most vegetables prefer slightly acidic soil, around 6.0 to 7.0. A straightforward soil test kit from any garden center costs a few dollars and takes ten minutes. If your soil is too acidic, add lime. If it is too alkaline, add sulfur. The packet will tell you how much. You do not have to be exact — close is good enough.

If you are planting in an existing bed, pull out old plant debris and any weeds. Loosen the top few inches with a garden fork. If the soil looks compacted or depleted, work in another inch or two of compost.

Plant seeds or transplants at the correct depth

The seed packet tells you exactly how deep to plant. Tomato seeds go about one-quarter inch deep. Carrot seeds go one-quarter to one-half inch deep. Beans go one inch deep. Squash seeds go one inch deep. If you plant too shallow, seeds dry out. If you plant too deep, they rot or never sprout.

For transplants — seedlings you bought or started indoors — the rule is simpler: plant them at the same depth they were growing in their pot. The soil line on the stem should be at the same level as the soil in your bed. Tomatoes are the exception; you can bury them deeper, up to their first true leaves, and they will grow roots along the buried stem and become stronger.

After planting seeds, cover them with soil and press gently so the seed makes contact with the soil. Do not pack it hard. Water with a fine mist so you do not wash the seeds away. For transplants, fill the hole, firm the soil around the base, and water thoroughly.

Water consistently for the first few weeks

New seeds and transplants need steady moisture while they establish roots. Check the soil daily by pushing your finger an inch down. If it feels dry, water. Most raised beds need water every day or every other day in warm weather, depending on how much sun they get and how much compost you mixed in.

Water at the soil level, not on the leaves. Wet foliage invites fungal disease. A soaker hose or drip line is ideal because it delivers water slowly and directly to the roots. If you use a watering can, pour slowly and let the water soak in rather than running off.

After three to four weeks, most plants have roots deep enough to handle longer stretches between watering. You can back off to every two or three days, depending on weather. Once plants are established and growing actively, they usually need about one inch of water per week — from rain or from you.

Plant on the right schedule for your climate

Cool-season crops — lettuce, spinach, peas, broccoli, cabbage — tolerate frost and actually taste better in cool weather. Plant them in early spring, as soon as the soil is workable, or in late summer for a fall harvest. They mature in 40 to 60 days and can handle a light frost.

Warm-season crops — tomatoes, peppers, squash, cucumbers, beans — need soil and air temperatures above 60 degrees Fahrenheit and will rot or fail to germinate in cold soil. Wait until after your last spring frost date to plant them. You can find your frost date by searching "[your city] last frost date" online, or ask at a local garden center. Plant warm-season crops in late spring and early summer.

You can succession plant — sow lettuce seeds every two weeks from spring through early fall — to have a continuous harvest instead of one big crop all at once. Do the same with beans and squash if you want fresh vegetables over several months rather than all in July.

Thin seedlings and remove weak transplants

If you planted seeds directly in the bed, they will sprout close together. Once they have two true leaves — the second set that appears after the seed leaves — thin them out. Snip the weaker seedlings at soil level with scissors rather than pulling them, which can disturb the roots of the ones you are keeping. Space them according to the seed packet.

If you planted transplants and one looks weak or diseased after a week or two, pull it out and replace it. A struggling plant takes up space and resources without producing much. It is better to remove it early and give the healthy ones more room.

Support tall plants and manage growth as they mature

Tomatoes, peppers, and squash grow large and need support or space to sprawl. Install stakes or cages at planting time, not later — driving a stake through roots damages them. Tomato cages should be at least 5 feet tall for indeterminate varieties; 3 feet is enough for determinate types. Tie stems loosely to the stake with soft twine or cloth strips as they grow.

Squash and cucumbers can climb a trellis if you train them, saving space and improving air flow. Beans will climb a pole or string on their own. Lettuce and root crops do not need support.

Pinch off the lowest leaves on tomatoes once the plant is 12 inches tall — this improves air flow and reduces disease. Remove any leaves that touch the soil. As plants grow, they may shade each other; thin out crowded foliage if air cannot circulate.

Frequently Asked Questions

Can I plant different vegetables right next to each other?

Yes, as long as you follow spacing for each plant's mature size. A tomato needs 24 to 36 inches from another tomato, but it can be 12 inches from a basil plant. Basil and lettuce can be very close. Check the seed packet for each plant's spacing requirement and plan accordingly.

What if my raised bed is only 6 inches deep?

You can grow lettuce, spinach, radishes, and shallow-rooted herbs. You cannot grow tomatoes, peppers, or root crops like carrots. If you want more options, add soil to reach 8 to 12 inches, or plan a second bed with more depth.

How often should I fertilize after planting?

If you mixed compost into your soil before planting, most vegetables do not need extra fertilizer for the first month. After that, a balanced fertilizer every two to three weeks keeps heavy feeders like tomatoes and squash productive. Lettuce and root crops need less. Follow the package directions for amounts.

Can I plant seeds and transplants in the same bed at the same time?

Yes. Plant transplants where they need their full mature space, and plant seeds in the gaps between them. The seeds will mature as the transplants grow and fill in. This works well for mixing fast crops like radishes with slow ones like tomatoes.

What should I do if seedlings look pale or yellow?

Pale seedlings usually mean they are not getting enough nitrogen. If they are less than three weeks old, wait — they may just be using stored energy. If they stay pale, mix a diluted liquid fertilizer into your watering can and explore it every week until color returns. Yellowing lower leaves on mature plants is normal as they age.