Raised beds are the most popular way to grow vegetables for good reason: they warm up earlier in spring, drain better than flat ground, keep the soil loose because you never walk on it, and make gardening easier on your back and knees. This guide covers vegetables raised bed gardening properly: the right bed size and depth, what to fill beds with, which vegetables suit raised beds best, how to water and feed them, and the mistakes that waste money and effort. The timings and spacings below use published ranges for common vegetables, which vary by variety, climate and soil, so treat them as a guide. As with everything in this guide, check your local extension service for advice suited to your area.
A raised bed is simply a box of soil above ground level, usually made from timber, stone or metal, and filled with a good growing mix. The box itself matters less than the soil inside it and the way you plant it. A bed that is too wide is hard to reach across; a bed that is too shallow starves deep-rooted vegetables; a bed filled with poor soil grows poor vegetables. Get the size, depth and soil right, and a raised bed will produce more food per square foot than almost any other way of growing.
Bed size, depth and layout
| Detail | Guidance |
|---|---|
| Width | 4 feet (1.2 m) — reachable from both sides without stepping in |
| Length | 8 feet (2.4 m) is a good starter size; longer is fine |
| Depth | 12 inches minimum; 18 inches better for root vegetables |
| Path between beds | 18–24 inches, wide enough for a wheelbarrow |
| Material | Untreated timber, stone, brick or metal; avoid old treated wood of unknown origin |
| Position | Full sun — at least six hours a day — near a water supply |
Four feet wide is the key measurement: you can reach the middle from either side without stepping on the soil, and the soil stays loose for years. Twelve inches deep is enough for lettuce, spinach, radishes, beans and most leafy vegetables, but root vegetables need more — carrots, parsnips and potatoes do best in beds 18 inches deep or more, and a shallow bed gives you short, stubby roots. If you are building on concrete or very poor ground, go deeper rather than wider. Leave paths wide enough for a wheelbarrow, and put the beds where they get full sun. The raised bed soil calculator works out how much mix you need for any bed size, and the soil volume calculator does the same for individual beds and containers.
What to fill raised beds with
Fill beds with a mix, not with a single material. A good raised bed mix is roughly 60 percent topsoil, 30 percent compost, and 10 percent drainage material such as coarse grit, perlite or vermiculite — or, if you prefer a simpler recipe, equal parts topsoil, compost and coir or peat-free potting mix. Do not fill a bed with pure compost: it shrinks as it breaks down, holds too much water in wet weather, and lacks the mineral structure that roots need. Do not fill it with pure garden soil either, especially heavy clay, which compacts and drains badly.
Top the bed up every year, because the mix settles and breaks down — a few inches of fresh compost dug into the top each spring is enough. The raised bed soil mix guide gives the full recipe, and the composting basics guide explains how to make the compost that keeps beds fertile year after year. If your budget is tight, fill the bottom half of a deep bed with bulky organic material — straw, leaves, small branches — and put the good mix on top. It breaks down slowly and feeds the soil, though the bed will settle more in the first year.
Which vegetables suit raised beds
| Vegetable | Spacing | Days to maturity | Raised-bed notes |
|---|---|---|---|
| Lettuce | 8–12 inches | 45–60 | Excellent; sow little and often |
| Carrots | 2–3 inches | 60–80 | Needs 18-inch depth; loose, stone-free mix |
| Tomatoes | 24–36 inches | 60–85 | One plant per 2 square feet; stake from the start |
| Green beans | 4–6 inches | 50–65 | Bush types suit beds; climbing types need a trellis |
| Kale | 12–18 inches | 50–65 | Pick leaf by leaf for months |
| Zucchini | 36–48 inches | 45–55 | One plant per bed corner; let it sprawl over the edge |
| Cucumbers | 36–48 inches | 50–70 | Train up a trellis to save space |
| Potatoes | 12 inches | 70–120 | Needs depth; earth up as stems grow |
| Onions | 4–6 inches | 90–120 | Plant sets in blocks, not rows |
| Beets | 3–4 inches | 50–70 | Thin to spacing; eat the leaves too |
| Spinach | 4–6 inches | 40–50 | Sow in spring and autumn |
Almost every vegetable grows well in a raised bed, but the best performers are the ones that benefit most from loose, warm, well-drained soil: carrots, potatoes, lettuce, tomatoes and beans. Carrots are the classic raised-bed success, because the deep, stone-free mix lets roots grow long and straight — in heavy garden soil the same variety forks and stunts. Tomatoes love the warmth of a raised bed in spring, but they need their full 24–36 inches of spacing, so do not crowd them. Zucchini needs 36–48 inches and will sprawl over the edge of the bed, which is fine — let it. Sweet corn is the one common vegetable that suits raised beds poorly, because it needs a block of plants for pollination and grows tall enough to shade everything else. The growing guide for carrots and the growing guide for tomatoes cover the two most popular raised-bed vegetables in detail.
Watering and feeding raised beds
Raised beds dry out faster than flat ground, because they drain freely and warm up in the sun. Water deeply and less often, preferably in the morning, and mulch the surface with straw or shredded leaves to hold moisture in. Tomatoes and celery are thirsty — tomatoes are rated high for water needs — while garlic is rated low and prefers to dry out. Most other vegetables sit in the middle at moderate. Push a finger into the soil: if it is dry an inch down, water. Drip irrigation or a soaker hose laid under the mulch is ideal for raised beds, since it waters the soil without wetting the leaves.
Feed beds every year. Dig a few inches of compost into the top each spring before planting, and side-dress heavy feeders such as tomatoes, zucchini, cucumbers and sweet corn with compost or a balanced fertiliser once they start fruiting. Beans and peas fix their own nitrogen and need little feeding. Do not overfeed: too much fertiliser produces lush leaves and few fruit, and fresh manure on carrots causes them to fork. The fertiliser calculator, the vegetables fertilizing guide and the mulching vegetables guide cover this in detail.
Planting plans, rotation and succession
Plant in blocks or squares, not long single rows. A 4-by-8-foot bed holds, for example, two tomato plants with basil between them, a block of lettuce, a block of carrots, and a row of beans along the north edge so they do not shade the rest. The plant spacing calculator helps you fit plants into your beds, and the vegetables spacing guide gives the spacing for each vegetable.
Rotate your vegetables: do not plant tomatoes, peppers, eggplants or potatoes in the same bed two years running, because they share diseases. Follow them with beans or peas, which add nitrogen, then with leafy vegetables, then with root vegetables. Sow a little, often — a short row of lettuce or radishes every two to three weeks gives a steady supply instead of a glut. And use the edges: let zucchini sprawl over the side, grow climbing beans up a trellis on the north edge, and tuck lettuce into the shade of taller plants in hot weather.
Common raised bed mistakes
- Building beds wider than 4 feet, so you have to step on the soil to reach the middle.
- Building beds shallower than 12 inches, so root vegetables have nowhere to go.
- Filling beds with pure compost, which shrinks and holds too much water.
- Filling beds with pure garden soil, especially heavy clay.
- Crowding tomatoes and zucchini, which need their full spacing to stay healthy.
- Forgetting that raised beds dry out faster and need more water than flat ground.
- Never topping beds up, so the soil level sinks year after year.
- Planting tomatoes in the same bed two years running.
Most raised bed mistakes are made once, at building time, and then lived with for years. Measure twice, build once, fill with a proper mix, and the bed will serve you for a decade.
Frequently asked questions
How deep should a raised bed be for vegetables?
At least 12 inches for most vegetables, and 18 inches or more for carrots, parsnips and potatoes. Deeper is better if you are building on concrete or poor ground.
What is the best soil mix for raised beds?
Roughly 60 percent topsoil, 30 percent compost and 10 percent drainage material, or equal parts topsoil, compost and coir. Do not use pure compost or pure garden soil — check your local extension service for mixes suited to your area.
How much soil do I need for a raised bed?
Use the raised bed soil calculator — a 4-by-8-foot bed, 12 inches deep, needs roughly 32 cubic feet of mix.
Do raised beds need more water?
Yes. They drain freely and warm up fast, so water deeply and mulch the surface to hold moisture in.
Can I grow tomatoes in a raised bed?
Yes — tomatoes love raised beds. Give each plant 24–36 inches of space, stake it from the start, and do not plant tomatoes in the same bed two years running.
Related guides
For more vegetable help, browse the guides hub and the growing guides hub, and try the raised bed soil calculator and the plant spacing calculator. Good next reads are the vegetables beginner guide, the vegetables container gardening guide, and the vegetables soil preparation guide. And as always, check your local extension service — local advice beats any general guide for your soil, your weather and your varieties.