Rhubarb Companion Plants
Rheum rhabarbarum · buckwheat family family · rotation group: other
The best companion plants for rhubarb are Asparagus, Cabbage, Garlic, Onion, and Strawberry. Avoid planting rhubarb near Curly Dock / Wild Dock, Sunflower, Corn. Of the 9 pairings recorded here, 1 is supported by published research and 8 are traditional practice with no controlled evidence behind them.
What to plant with rhubarb
| Plant | Claimed benefit | Evidence | What the evidence actually shows |
|---|---|---|---|
| Asparagus | Rhubarb and asparagus share a permanent full-sun bed at the edge of the garden. | Traditional | A siting recommendation, not a pest effect. NDSU Extension states that 'the end of an asparagus row is a suitable location' for rhubarb because both are full-sun perennials that must sit where the garden is not plowed or rototilled. No measured benefit either way. |
| Bush Bean | Bush beans are said to supply nitrogen to a heavy-feeding rhubarb crown. | Traditional | Not tested, and the mechanism is weak — legume nitrogen is largely released when the plants die and decompose, not passed to a neighbour during the season. Extension guidance for rhubarb fertility is composted manure or compost worked in each fall, not an interplanted legume. |
| Cabbage | Rhubarb grown near brassicas, or a piece of rhubarb stalk dropped into the planting hole, is said to protect cabbage from clubroot. | Traditional | Untested rather than disproven — no controlled trial and no US extension evaluation of it was found in this research pass. UMN Extension's companion-planting review notes that the origins of many such practices 'are hard to pinpoint' and that several popular ones are contradicted when tested. Do not rely on it: the established clubroot tools are resistant cultivars, long rotations, clean transplants and raising soil pH. |
| Garlic | Garlic planted around the rhubarb crown is said to deter rhubarb curculio and crown-boring pests. | Traditional | No test located. The measure that extension services actually recommend against rhubarb curculio is removing its alternate host: Illinois Extension advises destroying all wild dock growing around the garden. Garlic is not mentioned in any rhubarb pest guidance found. |
| Onion | Onions are said to be a good low neighbour for a rhubarb clump. | Traditional | Folklore with no supporting data. What it does get right by accident is scale: UMN Extension allocates each rhubarb plant a 3 ft by 3 ft area in all-day sun, so only a short crop that finishes early can share the edge without shading the clump. |
| Strawberry | Strawberries and rhubarb are commonly grown together as a low-maintenance perennial pairing. | Traditional | The pairing is culinary and logistical, not agronomic: both are perennials that suit an undisturbed bed. No pest or yield interaction has been tested, and strawberries are shallow-rooted competitors that need their own water and fertility. |
What not to plant with rhubarb
| Plant | Claimed problem | Evidence | What the evidence actually shows |
|---|---|---|---|
| Curly Dock / Wild Dock | Wild dock growing near the garden sustains rhubarb curculio and should be eliminated. | Research-backed | This one is grounded in documented host biology rather than folklore: Illinois Extension states that rhubarb curculio 'bores into the stalks, crowns, and roots' and instructs gardeners to 'destroy all wild dock growing around the garden' because the beetle also attacks these related plants. It is extension pest-management guidance rather than a replicated field trial, but the alternate-host relationship is established, and dock is a Rumex relative of rhubarb in the same family. |
| Corn | Sweet corn planted beside rhubarb shades it out and competes for nutrients. | Traditional | Untested as a pairing. Same competition argument as sunflower, plus a practical one: corn is an annual that gets tilled in, and rhubarb is a decade-long planting that Iowa State and PSU both recommend siting where the bed will not be dug. |
| Sunflower | Tall heavy feeders such as sunflower are said to be poor rhubarb neighbours. | Traditional | No allelopathy trial involving rhubarb was found. The real and simple problem is light and space: UMN Extension calls for a spot receiving all-day sun and a full 3 ft by 3 ft per plant, so anything that overshadows the clump reduces stalk production. |
The honest verdict
None of the companion pairings commonly recommended for rhubarb have been confirmed in controlled trials that we could find. That does not make them harmful — it means the benefit is unproven, and you should plant for spacing, sun, and water compatibility first.
The remaining 6 pairings on this page are traditional practice. They circulate on every companion planting chart online, but we could not find controlled evidence testing them. They are not wrong so much as unverified — most cost nothing to try, and interplanting flowers and herbs has its own well-documented benefit of pulling pollinators and predatory insects into the garden.
Every row above links to the publication it came from. See how we grade evidence.
Growing rhubarb: the numbers
| Sun | Full sun (6+ hours) |
|---|---|
| Water | Moderate |
| Spacing | 36 in apart · 48 in between rows |
| Mature size | about 36 in tall |
| Soil pH | 5.5–7 |
| Days to maturity | 730–1095 days |
| Frost tolerance | Hardy — takes hard frost |
| Containers | Not well suited to containers |
| Typical yield | 4 to 12 lb of stalks per season depending on age and variety |
| Hardiness zones | 3–8 (perennial) |
| Common pests | rhubarb curculio, stalk borer, slugs |
| Common diseases | phytophthora crown rot, ascochyta leaf spot, ramularia leaf spot, anthracnose |
When to plant rhubarb
Zone 6b shownTransplant outdoors: Mar 6 – Mar 19 — 5 weeks before last frost
Expected harvest: Mar 5 — 730–1095 days from planting
Those dates are for zone 6b. Get your own dates by ZIP code →
Varieties worth knowing
crowns- Victoria — Green-stalked and the heaviest producer; Penn State calls it 'a very reliable performer with thicker stalks'. Grow rhubarb from crowns or divisions, not seed — NDSU notes seed-grown plants 'seldom equal the production or quality of the named rhubarb varieties'.
- Canada Red — Red-stalked cultivar listed by Iowa State, NDSU and Utah State; Penn State cautions that red types generally produce thinner and fewer stalks than Victoria.
- MacDonald — Vigorous red-stalked cultivar recommended by Iowa State, Penn State, NDSU and Utah State; a good all-round garden choice.
- Valentine — Deep red stalks that hold their colour when cooked; recommended for the Upper Midwest and Northern Plains by Iowa State, Wisconsin and NDSU.
Variety names link to crowns on Amazon. As an Amazon Associate we earn from qualifying purchases. These are the varieties named in the extension sources for this crop, not a paid placement — where a source recommended a variety for a specific reason, that reason is the note beside it.
Put it in a bed
The garden planner checks every square against this ledger as you place crops — if you drop rhubarb next to something recorded as a bad neighbour, the square turns red and tells you why.
Records for the plants named above:
Same rotation group (other) — don't follow one with another:
Rhubarb companion planting questions
What should not be planted next to rhubarb?
How far apart should rhubarb be planted?
Does companion planting with rhubarb actually work?
When should I plant rhubarb?
Sources for this record
- University of Minnesota Extension — Growing rhubarb in home gardens (hardy in USDA Zone 4 and worth trying in Zone 3; leaves are toxic; soil pH is not important)
- Iowa State University Extension — Growing Rhubarb in Iowa
- Wisconsin Horticulture — Rhubarb, Rheum rhabarbarum (plant divisions 4-6 weeks before last frost with buds about 2 inches deep; grows 2-4 ft tall; leaves contain a toxic amount of oxalic acid and are poisonous)
- Utah State University Extension — Rhubarb in the Garden (a plant yields 4 to 12 pounds of stalks annually)
- NC State Extension Plant Toolbox — Rheum rhabarbarum: poisonous parts are the leaves and roots, toxic principle 'anthraquinone glycosides and soluble oxalates, also possibly calcium oxalate crystals'. Note on the folk practice of boiling rhubarb leaves into a homemade insecticide: no controlled efficacy data and no US Cooperative Extension recommendation for it was found in this research pass, and a home-brewed leaf spray is both toxic and an unregistered pesticide
Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.