Start with soil, not seeds

Fill your raised bed with soil before you plant anything. Most gardeners use a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts—this combination drains well while holding moisture and nutrients. A 4-by-8-foot bed that is 12 inches deep needs about 32 cubic feet of soil, which is roughly 1 cubic yard. You can buy bagged soil at a garden center or hardware store, or order bulk soil delivered.

Spread the soil evenly across the bed and water it thoroughly before planting. The soil will settle over the first week or two, so you may need to add more. Let the bed sit for a day or two after filling—this gives the soil time to absorb water and settle, making it easier to plant in.

Key Takeaways

  • Fill your raised bed with a mix of topsoil, compost, and peat moss or coconut coir in equal parts, then water it well before planting.
  • Plant seeds or seedlings at the depth and spacing listed on the seed packet or plant label, and water gently after planting.
  • Space plants closer together in raised beds than in ground gardens because the soil is richer and drainage is better.
  • Water your raised bed in the early morning or late afternoon, aiming for the soil rather than the leaves, and check moisture daily during hot weather.
  • Most vegetables and herbs are ready to plant in spring after the last frost date in your area, which you can find through your local cooperative extension office.

Choose what to plant based on your frost date

The best time to plant depends on when frost stops in your area. Find your local frost date by searching "[your city] last frost date" or by contacting your county's cooperative extension office—they have this information for free. Cool-season crops like lettuce, spinach, peas, and broccoli can go in the ground 2 to 4 weeks before the last frost date. Warm-season crops like tomatoes, peppers, squash, and beans must wait until after the last frost date has passed.

If you are planting from seed, read the seed packet for the exact timing and depth. If you are buying seedlings from a nursery, the label will tell you when to plant and how far apart to space them. Seedlings are faster and more reliable for beginners—they are ready to produce in 4 to 8 weeks, while seeds may take 8 to 12 weeks.

Plant seeds or seedlings at the right depth

The seed packet or plant label tells you exactly how deep to plant and how far apart. A general rule: plant seeds at a depth equal to twice their width. Tiny seeds like lettuce or carrot go barely under the soil surface. Larger seeds like beans or squash go 1 to 2 inches deep. Seedlings go in at the same depth they were growing in their container—the soil line on the stem should be at ground level, not buried higher.

Make a small hole with your finger or a trowel, place the seed or seedling in, and gently press soil around it. Water lightly right after planting so the soil makes contact with the seed or roots. Do not pack the soil down hard; raised bed soil should stay loose so roots can push through easily.

Space plants closer in raised beds than in ground gardens

Raised beds allow tighter spacing than traditional rows because the soil is deeper and richer, and water drains better. A tomato plant that needs 24 inches between plants in a ground garden can often go 18 inches apart in a raised bed. Lettuce and other leafy greens can be planted 6 to 8 inches apart instead of 12. Check your seed packet or plant label for the recommended spacing, then reduce it by about 20 percent.

Closer spacing means more plants per bed and a faster harvest, but it also means less air circulation. Watch for crowding as plants grow, and thin seedlings early if they are too close. Remove the smaller or weaker seedling by pinching it off at soil level rather than pulling it out, which can disturb the roots of the plant you want to keep.

Water in the morning and check soil moisture daily

Water your raised bed in early morning or late afternoon, not in the heat of midday. Aim the water at the soil, not the leaves—wet foliage invites fungal disease. Raised beds dry out faster than ground gardens because they have more surface area exposed to sun and wind, so check the soil moisture every day during warm weather. Stick your finger 2 inches into the soil; if it feels dry, water deeply until water drains from the bottom of the bed.

Most vegetables need about 1 to 2 inches of water per week, including rain. A soaker hose or drip line is more efficient than overhead watering because less water is lost to evaporation and runoff. If you use a soaker hose, lay it on the soil surface and cover it lightly with mulch to keep it in place and reduce evaporation.

Add mulch to keep soil cool and moist

Spread 2 to 3 inches of mulch over the soil around your plants once they are established—wait until seedlings have their first true leaves. Use straw, shredded leaves, or wood chips. Mulch keeps soil cooler in summer, reduces water loss, and slows weed growth. Keep mulch a few inches away from plant stems to prevent rot and pest damage.

As mulch breaks down over the season, it adds organic matter to your soil. By the end of the growing season, you may need to add fresh mulch. In fall, you can leave the old mulch in place and add compost on top; it will decompose over winter and enrich the bed for next year.

Fertilize every 3 to 4 weeks during the growing season

Raised bed soil is rich at first, but nutrients get used up as plants grow. Once plants are 4 to 6 inches tall, start fertilizing every 3 to 4 weeks. Use a balanced fertilizer like 10-10-10 or a fish emulsion, following the label instructions for the amount. Organic options include compost tea, seaweed extract, or a granular organic fertilizer worked into the top inch of soil.

Heavy feeders like tomatoes, peppers, and squash need more fertilizer than light feeders like lettuce or herbs. If leaves start to yellow or growth slows, that is a sign your plants need feeding. Always water before and after fertilizing to prevent burning the roots.

Frequently Asked Questions

Can I plant in a raised bed right after filling it?

Yes, but it is better to wait a day or two. New soil needs time to settle and absorb water evenly. If you plant when ready, the soil may shift as it settles, which can disturb seeds or seedlings. Watering the bed the day before you plant makes the soil easier to work with and gives seeds better contact with moist soil.

What if my raised bed is in partial shade?

Most vegetables need at least 6 hours of direct sun per day. Leafy greens like lettuce and spinach can tolerate 4 to 5 hours. Tomatoes, peppers, and squash need 8 hours or more. If your bed gets less than 6 hours, stick to shade-tolerant crops like kale, chard, parsley, and mint. Measure the shade at different times of day to know exactly how much sun your bed receives.

How often should I water if it rains?

Check soil moisture after rain, just as you would on a dry day. Stick your finger 2 inches into the soil—if it feels moist, skip watering. If it feels dry, water anyway. Raised beds can drain quickly even after rain, especially in hot weather. Rain also does not always reach all parts of the bed evenly, so some areas may be dry while others are wet.

Can I plant different vegetables together in one bed?

Yes, and mixing plants often works better than planting one crop per bed. Fast-growing lettuce can be harvested before slower tomatoes need the space. Herbs like basil repel some pests. Avoid planting heavy feeders like tomatoes and squash together, since they compete for nutrients. Plant tall crops like tomatoes on the north side of the bed so they do not shade shorter plants.

What should I do at the end of the season?

Pull out dead plants and add them to a compost pile if they are disease-free. Leave roots in the soil to decompose and add organic matter. Spread 2 to 3 inches of compost over the bed in fall, and it will break down over winter. In spring, mix it into the top few inches of soil before planting. This keeps your soil rich and ready for the next season.