Start with soil depth and spacing to match tomato root needs

Tomatoes need at least 12 inches of soil depth, though 18 inches is better for full-size varieties. Fill your raised bed with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts—this gives roots room to spread while holding moisture and nutrients. Before planting, work in a balanced fertilizer (something like 10-10-10) according to the package directions, or mix in aged compost at about 2 to 3 inches deep.

Space determinate (bush) tomatoes 24 inches apart and indeterminate (vining) varieties 36 inches apart. If you are unsure which type you have, check the seed packet or plant label—it will say "determinate" or "indeterminate." Crowding tomatoes invites disease because air cannot move between leaves, so resist the urge to squeeze in extra plants.

Key Takeaways

  • Fill your raised bed with 18 inches of soil mixed with compost, and space plants 24 to 36 inches apart depending on whether they are bush or vining types.
  • Plant seedlings deep—bury the stem up to the first true leaves so roots form along the buried stem and anchor the plant better.
  • Water at the soil level early in the morning, aiming for 1 to 2 inches per week, and avoid wetting the leaves to prevent fungal disease.
  • Indeterminate tomatoes need stakes or cages for support; determinate types often stand alone but benefit from a single stake.
  • Pinch off suckers on indeterminate varieties and remove lower leaves once the plant is established to improve air flow and reduce disease.

Plant seedlings deep and water when ready after transplanting

Bury tomato seedlings deeper than they grew in their pots—remove the lower leaves and plant the stem up to the first set of true leaves (the leaves that look like actual tomato leaves, not the smooth seed leaves). Roots will form all along the buried stem, creating a stronger root system. Gently firm the soil around the base and water thoroughly until water drains from the bottom of the bed.

Plant seedlings in late spring after the last frost date for your area has passed and soil temperature is at least 60°F. If you plant too early into cold soil, the roots will sit dormant and the plant may rot. If you are unsure of your frost date, search "[your city] last frost date" online—local extension offices publish this for every region.

Water consistently at soil level, not on the leaves

Tomatoes need 1 to 2 inches of water per week, delivered at the base of the plant rather than overhead. Water early in the morning so any splash that does hit the leaves dries quickly. Wet leaves sitting in warm air invite powdery mildew and early blight, two common fungal diseases that spread fast in raised beds where air circulation is limited.

Check soil moisture by pushing your finger 2 inches into the soil—if it feels dry, water. If it feels moist, wait another day. Raised beds dry out faster than in-ground gardens, so you may need to water every other day in hot weather. Drip irrigation or soaker hoses work better than hand-watering because they deliver water slowly and directly to the roots without splashing the foliage.

Support indeterminate varieties with stakes or cages from the start

Indeterminate tomatoes grow 6 to 8 feet tall and need sturdy support. Install a stake or cage at planting time, before roots spread—driving a stake through roots later damages them. Use a cage at least 5 feet tall, or drive a 6-foot stake into the soil 6 inches from the stem and tie the plant loosely with soft twine or cloth strips as it grows. Avoid tying too tightly; leave room for the stem to expand.

Determinate varieties are bushier and shorter (3 to 4 feet), so they often stand without support, but a single stake prevents the fruit from dragging on wet soil where it can rot or pick up disease. Even a short cage helps keep fruit off the ground.

Prune suckers and lower leaves to improve air flow

On indeterminate tomatoes, suckers are shoots that grow in the angle between the main stem and a branch. Pinch these off when they are small—they drain energy from fruit production and create dense foliage that traps moisture. On determinate types, light pruning is optional; many gardeners leave them alone.

Once the plant is 12 inches tall and has set its first flower cluster, remove the lowest 6 to 8 inches of leaves. As the plant grows, continue removing leaves below the lowest fruit cluster. This opens up the base of the plant so air moves freely, drying morning dew and reducing fungal disease. Never remove more than one-third of the plant's leaves at once, or you will stress it.

Fertilize every two to three weeks once fruit sets

After the first flowers appear, switch to a fertilizer higher in phosphorus and potassium—look for a number like 5-10-10 on the package. This encourages fruit rather than leaf growth. explore every two to three weeks according to package directions, or side-dress with compost around the base of the plant. Avoid high-nitrogen fertilizers (the first number much higher than the others), which produce lots of leaves but few tomatoes.

If leaves turn pale yellow starting at the bottom, the plant may need nitrogen. If fruit is slow to ripen or has a hard spot on the bottom (blossom end rot), the plant needs more calcium—add crushed eggshells or a calcium supplement to the soil.

Harvest when fruit is fully colored but still slightly firm

Tomatoes ripen from the inside out, so wait until the fruit is fully colored all over before picking. A ripe tomato should yield slightly to gentle pressure but not feel mushy. Pick in the morning when the fruit is cool, and leave the stem attached if possible—it keeps the fruit fresher longer.

If frost threatens before your tomatoes ripen, pick all fruit that shows any color and set it on a windowsill indoors. Tomatoes continue to ripen off the vine as long as they are warm and out of direct sun. Green tomatoes will not ripen indoors, so only pick fruit that has started to change color.

Frequently Asked Questions

Can I grow tomatoes in a raised bed that is less than 12 inches deep?

Shallow beds slow growth and make it harder for roots to find water during dry spells, but determinate varieties can manage in 10 to 12 inches if you water consistently and add compost. Indeterminate types really need 18 inches to reach their full size. If your bed is shallow, choose bush varieties and plan to water more often.

What should I do if my tomato leaves turn yellow and curl?

Yellow leaves starting at the bottom are usually normal as the plant matures, but if yellowing spreads upward quickly or leaves curl inward, check for spider mites or early blight. Early blight shows brown spots with concentric rings. Remove affected leaves, improve air flow by pruning, and water only at soil level. If the problem persists, a sulfur or copper fungicide may help.

How do I know if my tomato plant needs more water?

Wilting during the day that recovers at night is normal, but wilting that does not recover by morning means the soil is too dry. Cracked or split fruit means the plant got too dry, then too wet. Aim for consistent moisture—not soggy, not bone-dry. Mulch the soil surface with 2 inches of straw or shredded leaves to slow evaporation.

Can I plant tomatoes in the same raised bed year after year?

Tomatoes are heavy feeders and leave soil depleted, so refresh the bed each spring by mixing in 2 to 3 inches of compost or aged manure. Rotating crops—growing tomatoes in one bed one year and beans or lettuce the next—reduces disease buildup. If you must plant in the same spot, remove the top 6 inches of old soil and replace it with fresh compost.

Why are my tomatoes not turning red?

Tomatoes need warmth to ripen—below 68°F, ripening slows dramatically. If nights are cool, pick fruit at the "breaker stage" (when the first blush of color appears) and ripen it indoors at room temperature. Too much nitrogen fertilizer also delays ripening by pushing leaf growth; switch to a phosphorus-rich formula once flowers appear. Shade from nearby plants or structures can also slow color development.