Companion Planting — Symbiosis Guide
Every plant in this system should serve at least two roles: feed the people, and feed the soil, repel pests, attract pollinators, or shelter a neighbor. This guide covers beneficial guilds, nitrogen fixers, dynamic accumulators, and combinations to avoid.
The Three Sisters — Annual Foundation Guild
The oldest known companion planting system. Three plants that support each other completely.
Plant in a mound. Corn first, beans 2 weeks later, squash after that. Minimum 3×3 ft per mound; 10×10 ft for meaningful yield.
🌽 Tall Layer
Anchor Corn — Vertical trellis for beans to climb; provides shade for squash · Center of mound
🫘 Mid Layer
Climber Beans — Fix nitrogen from air into soil, feeding corn and squash · Base of corn stalks
🎃 Ground Layer
Groundcover Squash — Broad leaves shade out weeds, retain moisture, deter pests · Outer edge of mound
Perennial Food Forest Guilds
A guild is a cluster of plants around one main crop. Each plant plays a role. Build these around every tree or shrub. Establish the central crop first; add companions in year one or two.
Apple / Pear Tree Guild
Plant the tree first. Add shrub layer in year 1–2. Fill ground layer in year 2–3.
🌳 Canopy
Anchor Apple or Pear — Central crop · Center
Herbaceous Rhubarb — Dynamic accumulator; good mulch, soil insulator · Drip line
Herbaceous Sunflowers — Edible seeds, attracts pollinators & birds, wind protection · North / west side
Climber Nasturtium — Edible, trap crop for aphids, insulates & covers soil · Outer ring
🌿 Shrub / Mid Layer
Shrub Blackcurrants — Edible, medicinal; attracts pollinators & birds, wind protection · Outer drip line
Shrub Raspberries — Edible, medicinal; berries & leaves used, wind protection · Outer edge
Herbaceous Onions — Edible, medicinal, pest deterrent · Under canopy
Herbaceous Dandelions — Edible, medicinal, dynamic accumulator, attracts pollinators · Outer ring
🌱 Ground / Herb Layer
Herbaceous Chives — Repel apple scab and aphids · Under canopy
Herbaceous Sage — Edible, medicinal, pest deterrent · Bed border
Shrub Oregano — Edible, medicinal, pest deterrent · Bed border
Herbaceous Marigolds — Edible, medicinal, pest deterrent, weed suppression · Outer ring
Groundcover White Clover — Nitrogen-fixing; weed suppressant, pollinator support · Ground cover
Herbaceous Yarrow — Attracts predatory wasps; mineral accumulator · Outer ring
🌰 Root Layer
Rhizome Carrots — Edible, weed suppression, loosens soil · Ground cover
Rhizome Beetroot — Edible, medicinal, natural dye · Ground cover
Rhizome Radish — Edible, bug trap, breaks compaction · Ground cover
Herbaceous Daffodil — Repels deer, moles, voles from root zone · Drip line ring
Chestnut / Nut Tree Guild
⚠ If using walnut: juglone toxicity affects many plants within 50–60 ft. Companions listed are juglone-tolerant.
🌳 Canopy
Anchor Chestnut or Walnut — Central crop · Center
Shrub Siberian Pea Shrub — Nitrogen-fixing windbreak; edible seeds · North / west side
🌿 Shrub / Mid Layer
Shrub Black currant — Mid-layer fruit; thrives in partial shade · Outer drip line
Herbaceous Comfrey — Mineral accumulator; chop-and-drop mulch · Drip line
🌱 Ground / Shade Layer
Groundcover Ramps / Wild leek — Ground cover under canopy; shade-tolerant; edible · Under canopy
Groundcover Ostrich fern — Shade-tolerant ground cover; edible fiddleheads · Under canopy
Groundcover White clover — Nitrogen-fixing; pollinator support · Ground cover
Elderberry Guild
Elderberry is a fast-establishing shrub. Add ground layer companions in year one.
🌿 Tall Shrub
Anchor Elderberry — Central crop; medicinal + culinary fruit · Center
Herbaceous Comfrey — Mineral mulch; accelerates elderberry establishment · Drip line
🌱 Ground Layer
Herbaceous Chives — Repel aphids at stem base · Base of shrub
Herbaceous Yarrow — Predatory insect habitat; mineral accumulator · Outer ring
Groundcover White clover — Nitrogen-fixing; living mulch · Ground cover
Climber Nasturtium — Trap crop for aphids (elderberry is an aphid magnet) · Outer ring
Mulberry / Pawpaw Guild
Both are high-yield native trees. Pawpaw prefers partial shade when young; mulberry is very fast to establish.
🌳 Canopy
Anchor Mulberry or Pawpaw — Central crop; high-yield native fruit · Center
Herbaceous Comfrey — Mineral accumulator; chop-and-drop mulch · Drip line
Herbaceous Yarrow — Predatory insect attractor; self-seeding · Outer ring
🌱 Ground / Shade Layer
Groundcover Ramps / Wild leek — Shade-tolerant ground cover; edible · Under canopy
Groundcover Good King Henry — Perennial spinach substitute; tolerates shade · Under canopy
Groundcover White clover — Nitrogen-fixing; pollinator support · Ground cover
🌰 Root / Deterrent Ring
Herbaceous Daffodil — Deer and vole deterrent around root zone · Drip line ring
Berry Shrub Guild
Applies to currant, gooseberry, aronia, and similar fruiting shrubs.
🌿 Shrub Layer
Anchor Berry shrub — Central crop (currant, gooseberry, aronia) · Center
Herbaceous Comfrey — Mulch; mineral mining from deep soil · Beside shrub
🌱 Ground Layer
Herbaceous Chives — Repel aphids and gooseberry sawfly · Base of shrub
Groundcover Strawberry — Living mulch; fills gaps; vitamin C crop · Ground cover
Groundcover White clover — Nitrogen-fixing; weed suppression · Ground cover
Climber Nasturtium — Trap crop for aphids; edible flowers · Outer ring
Annual Bed Guilds
Apply the same guild logic to annual beds — one central crop surrounded by plants that protect, feed, and attract.
Tomato Guild
Add companions at transplant time. Mulch sunken beds around tomato base. Rotate bed each year.
🌿 Tall Layer
Anchor Tomato — Edible, shades soil, deters carrot pests · Center / trellis
Herbaceous Sunflower — Attracts pollinators, wind protection, supports climbing beans · Outer edge
Shrub Borage — Edible, medicinal, deters tomato hornworm, attracts pollinators · Outer ring
🌱 Mid Layer
Herbaceous Onion — Edible, medicinal, deters pests, loosens soil · Between plants
Groundcover Basil — Deters aphids & whitefly, covers ground, improves tomato growth · Between plants
Climber Beans — Edible, fix nitrogen, climb sunflower stems · Outer edge
🍂 Ground Layer
Herbaceous Marigold — Edible, medicinal, repels nematodes & whitefly, attracts pollinators · Bed border
Groundcover Arugula — Edible, covers ground, attracts pollinators · Between plants
Climber Nasturtium — Edible flowers, trap crop for aphids, covers bare soil · Bed edge
🌰 Root Layer
Rhizome Carrot — Edible, loosens soil; plant 15 cm+ from tomato stem to avoid stunting · Between plants
Herbaceous Parsley — Edible, attracts predatory wasps, high vitamin K · Between plants
Brassica Bed Guild
Rotate brassicas annually — never plant in the same bed two years running.
🌱 Tall Layer
Anchor Brassicas — Central crop (kale, cabbage, broccoli, etc.) · Center
Herbaceous Dill — Attracts parasitic wasps that prey on caterpillars · Between plants
🍂 Ground / Herb Layer
Herbaceous Sage — Repels cabbage moth and white butterfly · Bed border
Groundcover Thyme — Repels cabbage worm; low ground cover · Bed edge
Herbaceous Chamomile — Improves brassica growth; attracts hoverflies · Between plants
Groundcover White clover — Nitrogen-fixing; living mulch between rows · Path / edge
Climber Nasturtium — Trap crop for aphids and caterpillars · Outer edge
Potato Guild
Rotate annually. Do not follow tomatoes or other solanums.
🌱 Mid Layer
Anchor Potatoes — Central calorie crop · Center
Climber Beans — Fix nitrogen; fill vertical space above low foliage · Edges
🍂 Ground / Border Layer
Herbaceous Horseradish — Repels Colorado potato beetle · Bed corners
Herbaceous Marigold — Repels nematodes and Colorado potato beetle · Bed border
Herbaceous Tansy — Repels Colorado potato beetle and ants · Outer edge
Herbaceous Yarrow — Mineral accumulator; predatory insect attractor · Outer ring
Annual Companion Pairings
| Plant | Good With | Why It Works |
|---|---|---|
| Tomatoes | Basil, marigold, carrot, parsley | Basil repels aphids + whitefly; marigolds repel nematodes |
| Carrots | Chives, rosemary, leeks, onions | Alliums repel carrot fly |
| Brassicas | Dill, celery, chamomile, sage | Dill attracts parasitic wasps; sage repels cabbage moth |
| Beans | Carrots, squash, marigold | Beans fix nitrogen for neighbors |
| Corn | Beans, squash, melon | Three Sisters logic; beans feed corn with nitrogen |
| Squash / Pumpkin | Corn, beans, nasturtium | Nasturtium repels squash beetles |
| Peppers | Basil, carrot, marjoram | Basil improves flavor and repels aphids |
| Lettuce | Tall crops (tomatoes, corn) | Needs afternoon shade in summer; uses space efficiently |
| Garlic | Roses, stone fruit, brassicas | Repels aphids, Japanese beetles, borers |
| Potatoes | Horseradish, marigold, beans | Horseradish repels Colorado potato beetle |
| Asparagus | Tomatoes, parsley, basil | Tomatoes repel asparagus beetle; asparagus repels nematodes |
| Onions | Carrots, beets, chamomile | Chamomile improves growth; deters pests |
| Cucumbers | Dill, beans, radishes | Radishes repel cucumber beetles; dill attracts predators |
Combinations to Avoid
| Avoid Planting Together | Reason |
|---|---|
| Onions + beans or peas | Alliums stunt legume growth |
| Fennel + almost everything | Allelopathic; keep isolated or in a pot |
| Potatoes + tomatoes | Same family; share blight disease |
| Walnut trees + most vegetables | Juglone (allelopathic compound) is toxic to many plants |
| Brassicas + brassicas (same bed, same year) | Same pest and disease pressure; rotate beds annually |
| Corn + tomatoes | Both heavy nitrogen feeders; compete aggressively |
Nitrogen Fixers — Feed the Whole System
| Plant | Type | Where to Use |
|---|---|---|
| White / Red Clover | Ground cover | Between all beds; orchard ground cover; paths |
| Beans (dry + fresh) | Annual | Rotate through every bed; follow with heavy feeders |
| Peas | Annual | Early spring crop before main crops go in |
| Siberian Pea Shrub | Shrub | Windbreak on north / west; fixes 70–100 lbs N/acre/yr |
| Autumn Olive | Shrub / tree | Edge of property — check local invasive regulations first |
| American Groundnut | Vine | Trellis near heavy-feeding trees or vegetable beds |
| Honey Locust (edible variety) | Tree | Canopy nitrogen fixer; pods are high-sugar livestock fodder |
Dynamic Accumulators — Mine Minerals from Deep Soil
Deep taproots pull up calcium, potassium, and trace minerals from layers shallow-rooted plants can't reach. Chop and drop as mulch throughout the season.
| Plant | Minerals Concentrated | How to Use |
|---|---|---|
| Comfrey | Calcium, potassium, phosphorus, B12 | Chop leaves 4–6×/season; use as mulch or liquid feed |
| Yarrow | Potassium, copper, phosphorus | Let self-seed at bed edges; cut before setting seed |
| Chicory | Calcium, potassium | Grow in rough areas; chop before seeding out |
| Dandelion | Calcium, iron, potassium | Let grow in paths and orchard; dig roots as needed |
| Horsetail | Silica, calcium | Compost tea or dried mulch for fungal-prone plants |
| Borage | Potassium, calcium | Annual that self-seeds; edible blue flowers; repels tomato hornworm |
Pest Control Through Planting
| Pest | Repellent Plants |
|---|---|
| Aphids | Chives, garlic, marigold, nasturtium (trap crop) |
| Carrot fly | Rosemary, sage, chives, onions — interplant with carrots |
| Cabbage moth / butterfly | Sage, thyme, mint, dill |
| Colorado potato beetle | Horseradish, tansy, marigold |
| Squash vine borer | Nasturtium; blue hubbard squash as sacrificial trap crop |
| Japanese beetle | Garlic, chives, rue |
| Deer | Daffodil ring border, lavender, sage, yarrow |
| Voles / moles | Daffodil bulb border rings around all beds |
Beneficial Insect Attractors
| Beneficial Insect | Plants That Attract It |
|---|---|
| Honeybees | Borage, phacelia, clover, lavender, fruit tree bloom |
| Predatory wasps | Yarrow, dill, fennel (isolated), carrot flower, angelica |
| Lacewings | Angelica, dill, coriander (let bolt) |
| Ground beetles | Dense ground cover; mulch; clover paths |
| Hoverflies | Phacelia, sweet alyssum, marigold, borage |
Pollinator Strip
A dedicated strip of sequenced-bloom plants keeps pollinators and beneficial insects on site from early spring through first frost. Plant once along a sunny edge or path — most self-seed year after year.
| Plant | Bloom Season | Who It Feeds | Notes |
|---|---|---|---|
| Phacelia | Early spring | Bees, hoverflies | One of the best early bee plants; self-seeds freely |
| Borage | Spring – summer | Bees, hoverflies | Self-seeds; edible blue flowers; also repels hornworm |
| White clover | Spring – fall | Bees, ground beetles | Living mulch between all beds; nitrogen fixer |
| Calendula | Spring – frost | Hoverflies, lacewings | Long bloom; edible petals; anti-inflammatory medicinal |
| Yarrow | Summer | Predatory wasps, hoverflies | Mineral accumulator; self-seeds; cut before setting seed |
| Sweet Alyssum | Summer – frost | Hoverflies, parasitic wasps | Low border plant; honey-scented; reseeds in mild climates |
| Dill | Summer | Wasps, lacewings, hoverflies | Let a few bolt; key predatory insect plant |
| Marigold | Summer – frost | Hoverflies | Also repels nematodes and whitefly throughout garden |
| Chamomile | Summer | Hoverflies, bees | Self-seeds; medicinal tea; companion to brassicas |
| Angelica | Late summer | Lacewings, predatory wasps | Biennial; large umbel flowers; seeds itself once established |