Garden Layout Companion Planting: Plans

Good garden layout companion planting is less about folklore and more about geometry: which plants shade which, whose roots feed at what depth, and who flowers when your pests arrive. A workable garden layout companion planting plan puts those relationships on paper before a single seed goes in, so you’re not untangling a basil plant from a squash vine in July. I’ve laid out beds for clients for years, and the difference between a mapped bed and a “we’ll see” bed is usually 20 to 30 percent yield and half the pest spray.

Why Layout Matters More Than the Pairing List

Most companion planting advice stops at “tomatoes like basil.” True, but useless without spacing. Plant basil 6 inches from a tomato stem and the tomato canopy buries it by week six. Put it 18 inches out on the sunny side and both thrive. Layout converts pairing lore into three real variables: distance between plants, height order relative to the sun, and timing of succession.

Height order is the one beginners miss. In the northern hemisphere, tall crops (corn, trellised tomatoes, pole beans) belong on the north edge of a bed so they don’t shade shorter partners. Mid-height crops (peppers, bush beans) take the middle. Low crops and living mulches (lettuce, thyme, alyssum) run along the south edge. Get this backwards and your “companions” become competitors for light.

Core Pairing Chart

Keep this short list taped inside the shed door. These pairings have mechanisms behind them, not just tradition:

• Tomato + basil + alyssum: basil may repel some thrips; alyssum feeds hoverflies whose larvae eat aphids. Space basil 15 to 18 inches from tomato stems.
• Corn + pole beans + squash (Three Sisters): beans fix roughly 40 to 80 lbs of nitrogen per acre equivalent; squash leaves shade out weeds and slow raccoons.
• Carrots + onions: onion scent disrupts carrot rust fly host-finding; alternate rows 3 inches apart.
• Cabbage family + dill or cilantro: umbel flowers feed parasitic wasps that attack cabbage worms.
• Cucumbers + nasturtiums: nasturtiums act as an aphid trap crop planted 2 feet off the cucumber row.
• Lettuce + tall crops: lettuce bolts above 75°F; afternoon shade from a tomato row extends the harvest 3 to 4 weeks.

And the anti-pairs: keep onions and garlic away from beans and peas (allelopathic effect stunts legumes), keep fennel away from nearly everything, and don’t plant potatoes beside tomatoes — shared blight is a real risk, not a myth.

Four Example Layout Plans

Plan 1: The Tomato-Basil Salsa Bed

Picture a rectangular bed roughly 4 feet deep and 8 to 10 feet long, oriented east-west. From north edge to south edge:

1. Row 1 (north): 4 to 5 indeterminate tomatoes on a cattle-panel trellis, 24 inches apart, stems 8 inches in from the back edge.
2. Row 2: 4 peppers alternating with 4 basil plants, 14 to 16 inches apart, set 20 inches south of the tomato line.
3. Row 3 (south): a ribbon of cilantro, bunching onions, and sweet alyssum, 6 inches apart, with 2 nasturtiums spilling over each corner.

Everything in a salsa recipe grows in one footprint, the tomatoes never shade the peppers, and the alyssum blooms by the time aphids show up. Budget 45 minutes to plant it and expect 40 to 60 lbs of tomatoes off a well-fed bed.

Plan 2: A Modern Three Sisters Block

Traditional Three Sisters wants a block, not a row — corn pollinates by wind and needs at least a 4×4 grid. Use a plot around 8 feet by 8 feet:

• Plant corn first in 5 mounds (center plus 4 corners of an inner square), 4 seeds per mound, mounds 30 inches apart.
• When corn hits 6 inches tall — usually day 18 to 21 — sow 3 pole beans per mound, 4 inches from the stalks. Planting beans on day one lets them strangle the seedling corn.
• Sow 2 winter squash seeds at the block’s outer edges the same week as the beans; thin to the strongest single vine per side.

Choose an 8-foot dent or flour corn over short sweet corn hybrids, which can’t carry bean weight. Yield from one block: roughly 25 to 40 ears, 2 to 3 lbs of dry beans, and 4 to 8 winter squash.

Plan 3: The Brassica-Protection Bed

Cabbage, broccoli, and kale attract the most persistent pests in the garden, so this layout is built around interference. In a bed about 4 feet across: set brassicas in two staggered rows, 18 inches apart each way. Between every second plant, drop in a dill or cilantro and let some flower. Along the south edge, run a strip of thyme and 3 to 4 calendula. Off one end — 3 to 4 feet away — plant a sacrificial patch of mustard greens as a trap crop for flea beetles; check it twice a week and knock beetles into soapy water.

Expect this arrangement to cut cabbage worm damage noticeably, but pair it with floating row cover for the first 4 weeks. Companions reduce pressure; they don’t create a force field.

Plan 4: A Container and Small-Space Version

Companion layout scales down to a patio surprisingly well because containers let you control soil per pairing. A 20-inch pot comfortably runs one determinate tomato, one basil, and a rim of alyssum — the salsa bed in miniature. A half-barrel handles the “pepper guild”: one pepper, two bunching onions, a thyme plant trailing the edge, and a marigold. Window boxes work as dedicated interference strips — fill one with alyssum, dill, and calendula and park it beside your vegetable containers so the beneficial insects commute 3 feet instead of 30. Two rules change in containers: spacing tightens by about 25 percent since you’re feeding and watering on demand, and aggressive partners (mint especially) finally become usable because the pot is the fence. Keep each container’s pairing to two or three species; a five-way jumble in 15 gallons of soil starves everyone by August.

Vertical elements earn their keep in small plans too. A single 4-foot trellis of pole beans on the north rim of a raised planter feeds nitrogen to the bed while shading a summer lettuce strip below it — a two-story companion stack in under 3 square feet of footprint.

Spacing Rules When Interplanting

Interplanting shrinks total footprint, but each plant still needs its mature diameter. Working numbers:

• Indeterminate tomatoes: 24 inches apart, companions no closer than 15 inches to the stem
• Peppers and bush beans: 14 to 16 inches
• Basil, parsley, marigolds: 10 to 12 inches
• Lettuce and spinach tucked as understory: 8 inches, harvested before neighbors close canopy
• Squash and cucumbers: 24 to 36 inches from anything they can bury

A useful check: sketch the bed at mature sizes, not transplant sizes. If two circles overlap more than a third, something moves.

Timing: Companions Are a Schedule, Not Just a Map

Succession is the invisible half of the plan. Radishes sown between future tomato positions finish in 25 to 30 days, right as tomatoes need the room. Lettuce planted with spring brassicas is out by the time summer heat arrives. Flowers need a head start — alyssum and calendula should be blooming, not germinating, when aphid season opens, so transplant them the same day as your vegetables or a week earlier.

Write actual dates on the plan. “Sow radish April 5, pull May 5, transplant tomato May 10” beats any pairing chart for keeping a bed productive.

Common Layout Mistakes

• Tall crops on the south edge — shades the whole bed by midsummer.
• One marigold per bed as a token gesture — pest effects need density; think ribbons and clumps, not single plants.
• Ignoring root depth — pairing two deep feeders (tomato and corn) in tight quarters starves both; mix deep and shallow rooters instead.
• Letting trap crops become nurseries — a nasturtium covered in aphids must be cut and bagged, or it’s breeding stock.
• No paths in the plan — leave an 18-inch reach zone; a layout you can’t harvest from gets trampled.

Putting Your Own Plan on Paper

Grab graph paper, one square per 6 inches. Draw the bed, mark north, and place plants in this order: tallest crops on the north line, then main mid-height crops at proper spacing, then herbs and flowers in the gaps, then quick succession crops penciled in with dates. Ten minutes of drawing in March saves a season of crowding, and the plan becomes next year’s record of what actually worked. Rotate plant families to a different bed each year — companions or not, brassicas following brassicas is how soil diseases settle in for good.