You have a 4×4 ft or 4×8 ft raised bed. Maybe two. You want tomatoes, peppers, lettuce, carrots, beans, herbs, and a flower or two — and you want to know what actually fits, what helps what, and what's going to be a disaster. Here's the answer in one sentence: divide the bed into one-foot squares, group plants by mature size, place tall crops on the north end, and pair tomatoes with basil, carrots with onions, brassicas with dill. That's 80% of the result. The rest of this article fills in the layout maps, the spacing math, and the pairings worth caring about.
Used well, a 4×8 ft (1.2 × 2.4 m) raised bed produces three full crop rotations per year, supports 30+ plants at any given time, and out-yields a same-size patch of in-ground row garden by 2× to 5× — using roughly 10% of the water and 20% of the space of conventional row gardening. The technique below is a hybrid: Mel Bartholomew's Square Foot Gardening grid for spacing, university-extension companion-planting research for pairings, and a few permaculture habits that make the bed self-managing after the first season.
The short answer
Divide your 4×8 ft (1.2 × 2.4 m) bed into 32 one-foot squares. Place tall crops (tomatoes, pole beans on a trellis) along the north edge so they don't shade smaller plants. Pair the heavy hitters: tomato + basil + marigold, carrots + onions, peppers + basil, brassicas + dill. Keep fennel, walnut roots, and the tomato-potato pair separated. Replant each section as crops finish to harvest 2–3× per year from the same square footage.
The 4-foot width isn't arbitrary. The average adult arm reaches about 24 inches (60 cm), so a 48-inch (1.2 m) wide bed lets you plant, weed, and harvest the centre from either side without ever stepping on the soil. Not stepping matters: every footprint in the bed compresses soil structure and breaks the network of roots and fungi you spent the first season building.
The 8-foot length gives you 32 square feet (3 m²) of growing area — enough for one focused planting theme (a salsa garden, a stir-fry garden, a cool-season greens bed) without becoming overwhelming. Square Foot Gardening assigns each square one of four planting densities depending on mature plant size: 1, 4, 9, or 16 plants per square. Garden in Minutes' SFG spacing chart covers more than 60 crops if you want the full reference, but you only need a handful for a productive bed.
| Plants per square foot | Spacing | Crops |
| 1 | 12 in (30 cm) | Tomato (indeterminate), pepper, eggplant, broccoli, cabbage, cauliflower, kale |
| 4 | 6 in (15 cm) | Bush beans, leaf lettuce, chard, parsley, basil, corn (better outside small bed) |
| 9 | 4 in (10 cm) | Beets, bush peas, spinach, turnips, leeks |
| 16 | 3 in (7.5 cm) | Carrots, onions, radishes, scallions, chives |
Source: The Natural Gardener — Square Foot Spacing Guide (PDF)
One translation rule covers everything: take the seed-packet "plant spacing" number, divide 12 by it, and square the result. A 3-inch spacing → 12 ÷ 3 = 4 → 4 × 4 = 16 plants per square. Ignore the "row spacing" number entirely — that's a relic of tractor-row planting and doesn't apply.
The layout below is a tested template — not the only good one, but a good starting point that bakes in three rules: tall plants on the north, companions paired naturally, and at least 4 squares of beneficial-insect habitat. Numbered from the north (back) to the south (front):
Row 1 (north, back) — climbers and tall fruit
4 squares: 1 indeterminate tomato per square (4 plants total) staked or caged, with a trellis on the north face. Pole beans climb up the trellis from squares behind. Marigold tucked into one corner of each tomato square (T. patula, planted at the same time as the tomato). The trellis must be at the back so it doesn't shade anything else.
Row 2 — peppers and basil
4 squares: 1 pepper per square, with basil interplanted at the corners (4 basil plants per pepper square). The basil masks tomato and pepper scent from thrips, and supports predatory lacewings. Penn State Extension documents 72–92% higher lacewing colonization in basil-intercropped tomato/pepper beds.
Row 3 — root crops, dense
4 squares: 16 carrots in two squares (alternating with 16 onions in two adjacent squares). The carrot–onion alternation is one of the few intercrops with peer-reviewed pest data — Uvah and Coaker's 1984 paper documented major reductions in carrot rust fly damage in mixed plantings. Bonus: carrots root deep, onions root shallow, so they don't fight for the same soil layer.
Row 4 — leaves and quick wins
4 squares: 4 lettuce plants per square (16 lettuces total) plus radishes scattered as row markers. Lettuce tolerates partial shade — and as the tomatoes grow tall behind, this row gets afternoon shade in summer, which keeps lettuce from bolting. Radishes mature in 25–30 days and act as a "place marker" — by the time you pull the last radish, the lettuce is ready to fill the gap.
That's 16 squares used. The remaining 16 squares are for what the season demands — a Three Sisters cluster (corn-bean-squash) if you have room and tolerance for the yield trade-offs, an insectary patch (alyssum, calendula, dill, borage at the south corners), or succession crops you'll plant in mid-summer for a fall harvest. UMass Extension notes that more diversity tends to mean less aphid pressure across the entire bed — a 4-broccoli-variety trial showed declining aphid loads as varietal diversity rose.
Why this works (the permaculture insight)
A monoculture is a buffet line for pests. Once they find one tomato, they find every tomato — same scent, same colour, same nutrient profile, all in a row. A polyculture jams the signal. Basil's volatiles overwrite the tomato scent. Marigolds disrupt the visual cue. Onions confuse the carrot fly. The whole bed becomes harder for any single pest to dominate, while pollinators and predators get a varied food supply that keeps them in residence. You're not "fighting pests" — you're building a system where pests can't get a foothold in the first place.
You don't need to memorise a 100-row companion chart. You need maybe a dozen pairings, all of which trace back to specific mechanisms — scent masking, beneficial insect support, nitrogen fixation, complementary root depth, or shade tolerance. Our complete companion planting chart covers every vegetable in detail; below are the pairings that earn their place specifically in a raised bed.
| Pair / trio | Why it works | Where to plant in a 4×8 bed |
| Tomato + basil + marigold | Basil masks scent from thrips and hornworm moths; marigold attracts hoverflies and pollinators | North row, 1 tomato per square, basil at corners, 1 marigold per 2 sq ft |
| Carrot + onion | Onion volatiles mask carrot scent from carrot rust fly; complementary root depths | Row 3, alternate 16-carrot and 16-onion squares |
| Pepper + basil | Basil supports lacewings that consume pepper aphids; both like warm, even moisture | Row 2, 1 pepper + 4 basil per square |
| Brassicas (broccoli, kale, cabbage) + dill + alyssum | Dill attracts parasitic wasps targeting cabbageworm eggs; alyssum brings hoverflies | Replace tomato squares in fall planting; alyssum at the south margin |
| Beans + corn + squash (Three Sisters) | Beans climb corn, fix nitrogen; squash shades soil and repels raccoons | Dedicated 4-square cluster; expect lower individual yields but high total nutrition |
| Lettuce + tall fruit (tomato, pepper) | Lettuce uses the afternoon shade tomatoes create — slows summer bolting | South side of any tall plant row |
| Peas + radish + spinach (spring) | All cool-season; peas fix nitrogen for follow-on summer crops | Whole bed in early spring, before warm-season replanting |
Sources: Penn State Extension, UMass Extension, and UC Master Gardeners (PDF).
Plants to keep apart in a raised bed
Fennel is allelopathic to almost everything — give it its own pot or the far corner of a different bed. Tomato + potato share early/late blight; one outbreak takes both. Onions/garlic + beans/peas — alliums leak compounds that suppress legume growth. Brassicas + strawberries compete and exchange growth-inhibiting chemistry. Dill + carrots at maturity — dill flowers attract carrot flies; keep them at opposite ends of the bed. See our 12 companion planting mistakes guide for the full list.
A raised bed is only as good as what's inside it. Mel Bartholomew's classic Mel's Mix remains the benchmark: equal volumes of coarse vermiculite, sphagnum peat moss (or coconut coir as a sustainable swap), and blended compost from at least 3 different sources. The mix is pH-neutral, drains freely, holds moisture without staying soggy, and feeds steadily — exactly what a high-density planting needs.
Depth matters more than most beginners think. GrowVeg's vegetable root-depth chart breaks crops into three depth classes: shallow (12–18 in / 30–46 cm) for lettuce, basil, radishes, herbs; medium (18 in / 46 cm) for carrots, beets, peppers, brassicas; and deep (24+ in / 61+ cm) for tomatoes, melons, winter squash. If you want indeterminate tomatoes to thrive, build the bed at least 18 inches deep — 24 inches is better. On hard surfaces (a patio, deck, or driveway), depth is non-negotiable: roots can't go down through concrete, so they need to go down through soil.
This also means you can't really separate raised-bed gardening from the deeper soil-building practices. Our soil health guide covers what to add each season; no-dig gardening explains how to top-dress without disturbing roots; and sheet mulching is how a lot of people fill or refresh deep beds on a tight budget.
| Item | DIY route | Premium route |
| Bed frame (untreated cedar) | $25–50 (3× 2"×6"×8' boards + screws) | $120–250 (pre-fab cedar kit) |
| Hardware cloth + landscape fabric | $50 (only if on hard surface) | $50 |
| Soil — 16 cu ft, 6" deep | $24–48 (bulk delivery, $1.50–3/cu ft) | $128 (bagged at $8/cu ft) |
| Soil — 32 cu ft, 12" deep | $48–96 (bulk) | $256 (bagged) |
| Seeds (8–10 packets) | $16–30 | $30 |
| Transplants (8–10 plants) | $10–20 | $20 |
| First-year total (12" deep) | $100–200 | $430–600 |
Source: Garden Betty — Plant Spacing for Raised Beds and bulk-soil pricing from regional landscape suppliers.
After year 1, the running cost drops fast. Most years you'll spend $40–80 on seeds, a couple of transplants, and 2–3 cubic feet of compost to top up the soil. The frame lasts 8–15 years in cedar; soil mix renews itself if you compost actively.
Want a printable 4×8 ft layout planner?
We'll send you a one-page grid template with companion suggestions for spring, summer, and fall — pre-filled examples plus blank squares for your own design.
Get the plannerOne bed planted three times is bigger than three beds planted once. In most temperate climates (USDA zones 5–8), a 4×8 ft raised bed can produce three sequenced harvests: cool-season spring, warm-season summer, cool-season fall. The trick is having the next round's transplants ready the moment the previous round finishes — which means starting seeds indoors 4–6 weeks ahead of every transition.
A typical Maryland-style rotation: peas, lettuce, radishes, spinach March–May; pole beans, tomatoes, peppers, basil June–September; kale, broccoli, carrots, lettuce again October–December. The same trellis serves peas in spring and pole beans in summer. The same square footage produces three harvests. Our companion spring companion planting guide covers the cool-season pairings; the cluster also includes deep dives on carrot companions, pepper companions, and flower companions that attract beneficial insects.
The other multiplier is going vertical. Pole beans in 1 sq ft of bed produce as much as bush beans in 3 sq ft of bed. Cucumbers on a trellis use a quarter the ground area of sprawling cucumbers. Indeterminate tomatoes pruned to a single stem and tied to a stake stay in their assigned square instead of taking over four. Grow Organic's pole vs. bush bean comparison notes that pole beans also extend the harvest window from 2–3 weeks (bush) to 8–10 weeks (pole) — more food, longer season, less ground.
Overcrowding. Enthusiasm gets the better of every first-year gardener. Plant fewer, more spaced, and you'll harvest more — the relationship between density and yield is a bell curve, not a line. Tall plants on the south side. Tomatoes 5 feet tall on the south end will shade everything else for half the day. Always put climbers and tall fruit on the north (or whichever side faces away from your sun in the southern hemisphere). Same family, same bed, year after year. Soil-borne disease and pest pressure compound. Rotate brassicas, nightshades, and alliums between beds (or sections within a bed) on at least a 3-year cycle. Ignoring root depth. Carrots in a 6-inch bed produce stunted roots. Tomatoes in a 12-inch bed on concrete stunt by August. Match the crop to the depth, or add depth to match the crop.
Want a permaculture-grade raised bed without the trial and error?
Our weekly newsletter walks through one design decision at a time — bed siting, soil mix, layout, succession planning, and the pairings worth caring about. No fluff, no upsells. Built for permaculture-curious gardeners who want a bed that gets easier each year, not harder.
Join the GrowPerma newsletterThe proven pairings for raised beds are: tomato + basil + marigold (scent masking, pollinator attraction), carrot + onion (mutual pest-scent confusion), pepper + basil (lacewing support), brassicas + dill + alyssum (parasitic wasp recruitment), peas + lettuce + radish (cool-season space sharing), and the Three Sisters cluster of corn + beans + squash. All of these have specific mechanisms — scent masking, beneficial-insect support, complementary root depth, or nitrogen fixation — that show up in extension service trials, not just in folklore.
Roughly 30–40 plants at any one time, depending on the mix. Using Square Foot Gardening density: 4 indeterminate tomatoes, 4 peppers, 4 marigolds, 16 basil plants, 32 carrots, 32 onions, 16 lettuces — that's already 108 plants from 32 squares. The number rises further with succession planting, since you'll cycle through 2–3 sets of crops over the season.
Stick to shallow-rooted crops: leaf lettuce, spinach, basil, parsley, chives, radishes, scallions, strawberries, and bush beans. Avoid anything that needs more than 12 inches (30 cm) of root depth — that rules out carrots, indeterminate tomatoes, broccoli, peppers, and most squash. A bed-with-legs is a herb-and-greens bed, not a tomato bed.
Onions, leeks, garlic, and chives all release sulfur compounds that mask the carrot's scent from carrot rust fly (Psila rosae). Uvah and Coaker's foundational 1984 study found that intercropping carrots with onions reduced carrot fly attack significantly. The pattern: alternate rows of carrots and onions in 16-per-square-foot density, or interplant within the same square. Keep dill at the opposite end of the bed — its flowers attract the carrot fly rather than repelling it.
Avoid planting peppers next to fennel (allelopathic), brassicas (compete heavily for nitrogen at the same time peppers need it), and any other Solanaceae crowded close — tomato + pepper + eggplant in the same row concentrates blight and hornworm risk. Beans and peas are sometimes flagged as antagonistic via allium-style nitrogen interference, but the effect is small in a well-fertilised raised bed. Keep peppers paired with basil, parsley, marigolds, carrots, or onions.
Yes — they make a good pair in a raised bed. Broccoli is a heavy feeder that occupies 1 plant per square foot at 12-inch spacing; carrots are light feeders at 16 per square. Their root depths don't conflict (broccoli is medium, carrots are medium-deep), and pest pressures don't overlap meaningfully. Add dill or alyssum nearby to bring in parasitic wasps that target cabbageworms on the broccoli. The one caveat: harvest the broccoli before the carrots mature, since carrots need full sun once they're sizing up roots.
Twelve inches (30 cm) is the practical minimum, but 18 inches (46 cm) is much better and 24 inches (61 cm) is ideal if you want indeterminate tomatoes, melons, or winter squash. The deeper bed lets you grow the full range of companion combinations including deep-rooted crops; a shallower bed limits you to the shallow- and medium-rooted families. On a hard surface (concrete, deck, driveway), don't go below 18 inches — roots can't escape downward, so the soil column is the entire root zone.