Companion Planting Chart: The Complete Guide with 50+ Plant Pairs

You can boost tomato yields by up to 34 % simply by planting the right neighbor—no chemicals, no extra water, just a few inches of basil. That isn’t a marketing gimmick; it’s a repeatable result documented by the University of Florida’s Horticultural Sciences Department in 2021. Companion planting works because plants exchange volatile compounds, attract beneficial insects, and balance soil nutrients. For a hands‑in‑the‑dirt gardener, the payoff is measured in bigger harvests, fewer sprays, and a garden that feels like a living, self‑regulating system. This guide compiles more than 50 proven plant pairs, complete with exact spacing, sowing windows, USDA hardiness zones, and real‑world cost estimates. Whether you’re a Zone 5 backyard grower or a Zone 9 community farmer, you’ll find a ready‑to‑print chart and troubleshooting tips for the inevitable mis‑matches. Grab a notebook, a trowel, and let’s turn anecdotal folklore into a data‑driven planting plan you can trust.

Principles Behind Successful Companion Pairings

First, understand that “companionship” is a three‑part equation: pest suppression, nutrient exchange, and micro‑climate modification. A 2019 study in the journal *Agronomy* showed that intercropping marigold (Tagetes × erecta) with cucumber reduced cucumber aphids by 27 % compared with monoculture plots.

Second, timing matters. If you sow carrots (Daucus carota ‘Nantes’) two weeks before planting onions (Allium cepa ‘Walla Walla’), the carrots establish a root network that lessens nitrogen competition, as reported by the Ohio State University Extension in 2020.

Third, spacing dictates the balance between competition and cooperation. For example, planting basil (Ocimum basilicum ‘Genovese’) 12 in (30 cm) away from tomatoes (Solanum lycopersicum ‘Early Girl’) provides enough aromatic oil diffusion without shading the tomato foliage. In contrast, a 4‑in (10‑cm) gap leads to leaf‑curl disease spikes, a failure noted in the Missouri Master Gardener’s 2022 field notes.

How to Read the Chart – Layout, Spacing, and Timing

When you map the chart onto a raised bed that is 4 ft × 8 ft, calculate total plant numbers by dividing the bed area (32 sq ft) by the square footage per pair (e.g., 12 in × 12 in = 1 sq ft per tomato‑basil pair). That yields 32 pairs, or 64 plants total. Adjust for pathways by subtracting 1 ft × 8 ft for a central walk, leaving 24 sq ft for planting, which reduces the count to 24 pairs.

Price verification is simple: a packet of Burpee’s ‘Heirloom Tomato Mix’ (30 seeds) sells for $3.49, while the same quantity of ‘Basil Seed Mix’ (100 seeds) is $2.79. Multiply by the number of pairs you plan to plant to budget accurately; for a 48‑pair garden, seed costs total roughly $150.

Top 20 Classic Pairs – Proven Winners

These pairings appear in multiple university extension publications and have been replicated by seasoned growers. Below, each bullet gives the cultivar, spacing, planting window, and a quantitative benefit.

Tomato ↔ Basil (Ocimum basilicum ‘Genovese’) – 12 in (30 cm) apart; plant basil 2‑3 weeks after tomato seedlings; zones 4‑9; yields rise 34 % (UF 2021); seed cost $2.99 / packet.
Cabbage ↔ Dill (Anethum graveolens ‘Bouquet’) – 18 in (45 cm) row spacing; sow dill 10 days after cabbage transplant; zones 5‑8; cabbage head weight ↑ 22 % (Cornell 2020); dill seed $1.79 / packet.
Carrot ↔ Onion (Allium cepa ‘Walla Walla’) – 3 in (8 cm) between carrot rows, 6 in (15 cm) between onion rows; plant carrots early March, onions early April; zones 3‑7; onion bulb diameter ↑ 15 % (USDA 2022); seed combo $3.20 / packet.
Beans ↔ Corn (Zea mays ‘Silver Queen’) – 4 in (10 cm) bean spacing, 12 in (30 cm) corn spacing; plant corn 2 weeks before beans; zones 4‑9; beans yield ↑ 28 % (Iowa 2018); seed cost $4.50 / bag.
Strawberries ↔ Borage (Borago officinalis ‘Blue’) – 12 in (30 cm) apart; plant borage after strawberries fruit; zones 5‑9; strawberry marketable fruit ↑ 19 % (North Carolina 2021); borage seed $2.50 / packet.
Potatoes ↔ Marigold (Tagetes erecta ‘French Marigold’) – 12 in (30 cm) between potato rows, 6 in (15 cm) between marigolds; plant marigold at potato hilling; zones 3‑8; tuber scab reduced 41 % (Virginia 2020); marigold seeds $1.99 / packet.
Peas ↔ Radish (Raphanus sativus ‘Cherry Belle’) – 2 in (5 cm) between peas, radish interspersed every 6 in; sow radish 1 week before peas; zones 4‑9; pea pod length ↑ 12 % (Michigan 2019); radish seed $1.45 / packet.
Lettuce ↔ Caraway (Carum carvi ‘Mammoth’) – 10 in (25 cm) spacing; plant caraway when lettuce is 3 in tall; zones 5‑9; lettuce pest damage ↓ 33 % (University of Wisconsin 2022); caraway seed $2.10 / packet.
Squash ↔ Nasturtium (Tropaeolum majus ‘Alaska’) – 3 ft (90 cm) between squash vines, nasturtium seeded 12 in away; sow nasturtium after squash vines twine; zones 4‑10; squash beetle infestation ↓ 27 % (Cornell 2021); nasturtium seed $2.75 / packet.
Spinach ↔ Strawberries (Fragaria × ananassa ‘Seascape’) – 6 in (15 cm) between spinach rows, strawberries 18 in apart; plant spinach early March, strawberries after last frost; zones 5‑9; spinach leaf chlorophyll ↑ 18 % (Penn State 2020); strawberry runner cost $4.99 / plant.

20 Innovative & Under‑Utilized Pairings

Beyond the classics, research and on‑farm trials reveal hidden synergies. These combinations often involve herbs, pollinator magnets, or soil‑modifying crops that mainstream guides overlook.

One example is rosemary (Rosmarinus officinalis ‘Tuscan Blue’) with beans (Phaseolus vulgaris ‘Blue Lake’). Rosemary’s aromatic oils deter bean beetles; a 2023 Colorado State University trial reported a 16 % increase in bean pod weight when rosemary was planted 18 in away.

Another promising duo is kale (Brassica oleracea ‘Winterbor’) with chamomile (Matricaria recutita ‘German’). Chamomile attracts hoverflies, which prey on aphids; in a 2022 study from the University of Minnesota, kale leaf damage dropped 38 % and marketable leaf mass rose 21 %.

Rosemary ↔ Beans – 18 in (45 cm) spacing; plant rosemary after beans are established (mid‑June); zones 7‑10; bean yield ↑ 16 % (CSU 2023); rosemary cutting cost $3.20 / plant.
Kale ↔ Chamomile – 12 in (30 cm) between kale rows, chamomile interplanted every 24 in; sow chamomile 2 weeks before kale transplant; zones 4‑8; aphid counts ↓ 45 % (UMN 2022); chamomile seed $1.60 / packet.
Mint ↔ Cabbage – 24 in (60 cm) mint border; plant mint after cabbage harvest to avoid allelopathy; zones 5‑9; cabbage rot incidence ↓ 30 % (Virginia 2021); mint starter $2.99 / pot.
Sunflower ↔ Pumpkin (Cucurbita maxima ‘Jack O’Lantern’) – 2 ft (60 cm) between sunflowers, pumpkins 3 ft apart; plant sunflowers 3 weeks before pumpkin; zones 3‑9; pumpkin vines climb sunflowers, reducing vine‑breakage by 22 % (Iowa 2020); seed cost $5.40 / bag.
Thyme ↔ Eggplant (Solanum melongena ‘Black Beauty’) – 10 in (25 cm) thyme strip beside eggplant; plant thyme at eggplant transplant (early May); zones 7‑10; eggplant fruit set ↑ 14 % (University of California 2021); thyme seed $2.20 / packet.
Fennel ↔ Dill – 12 in (30 cm) spacing, but keep varieties separate because fennel can inhibit dill; plant dill 2 weeks after fennel seedlings; zones 5‑9; dill oil content ↑ 9 % (Ohio Extension 2022); fennel bulb price $1.30 / lb.
Garlic ↔ Strawberries – 6 in (15 cm) between garlic cloves, 18 in between strawberry plants; plant garlic in fall (Oct‑Nov) and strawberries in early spring; zones 4‑8; strawberry fungal disease ↓ 35 % (USDA 2021); garlic seed $0.99 / lb.
Lavender (Lavandula angustifolia ‘Hidcote’) ↔ Sage (Salvia officinalis ‘Berggarten’) – 15 in (38 cm) apart; sow both in early spring; zones 6‑9; pollinator visits ↑ 27 % (University of Colorado 2022); lavender plant $4.50 / pot.
Radicchio ↔ Chicory – 8 in (20 cm) spacing; plant radicchio 3 weeks before chicory; zones 5‑9; bitter leaf compounds balanced, reducing pest pressure by 18 % (Penn State 2020); seed cost $2.70 / packet.
Watermelon ↔ Tansy (Tanacetum parthenium) – 4 ft (120 cm) between watermelon hills, tansy 12 in away; plant tansy after watermelon vines set; zones 7‑10; cucumber beetle damage ↓ 40 % (Georgia Extension 2021); tansy seed $1.45 / packet.

Zone‑Specific Adjustments – Making the Chart Work Everywhere

USDA zones dictate when and how you can execute each pair. In Zone 4 (e.g., Minneapolis), the frost‑free window is about 120 days, so you must start cool‑season crops like peas and kale indoors 6 weeks before the last frost (approx. March 15). For a pea‑radish pair, sow radish 10 days after transplanting peas to avoid early root competition.

Conversely, Zone 9 gardeners (e.g., Austin, TX) enjoy a 300‑day season, allowing a second round of warm‑season pairs. A summer planting of basil ↔ tomato can be followed by a fall planting of garlic ↔ strawberries, as garlic needs a cold period for vernalization; a simple mulch of 3 in (7.5 cm) straw ensures winter soil temperatures drop below 40 °F, satisfying the chilling requirement.

Price differentials also vary by region. In the Pacific Northwest, high‑quality heirloom seed packets from Seed Savers Exchange sell for $4.95 / packet, while the same cultivars from a local co‑op cost $3.20 / packet. Adjust your budget sheet accordingly; for a 30‑pair garden, total seed cost may range $150–$210 depending on source.

Managing Failures – When Companions Turn Against Each Other

Not every pairing works on every plot. Allelopathic compounds from black walnut (Juglans nigra) can inhibit tomato and basil, leading to stunted growth up to 28 % (University of Illinois 2019). If you spot yellowing foliage and low yields, test soil for juglone using a Home‑Made kit ($9.99 on Amazon) and consider raised beds with a 12‑in (30‑cm) barrier of clean topsoil.