Rhubarb
Rheum rhabarbarum
Also known asPie plant · Garden rhubarb · Rabarber
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 3–8 (winter low around -40°C)
- Frost
- very hardy (survives deep cold)
- Season
- cool (spring/fall)
Growing systems
Root mass: heavy. Thin-channel systems can't hold this crop.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Soil-based mix (Potting soil) | varies | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 2 | 1 | 1 | 1 |
| vegetative | 2 | 1 | 2 | 1.6 |
Aquaponics suitability
Not recommended
Fish waste alone doesn't supply enough of what this crop demands. Grows in hybrid systems with supplemental dosing, but expect active management.
Care notes
A perennial for outdoor aquaponics media beds or large containers (30 L). EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: cold-climate crop (USDA zones 3-8); needs winter freezing for dormancy. Full sun to partial shade (DLI 14-20 mol/m2/day). Plant divisions (pieces of crown with roots) in early spring. Do not harvest any stalks in the first year; let the plant build root reserves. In year 2, harvest lightly (a few stalks). From year 3 onward, harvest freely for 8-10 weeks in spring, then stop to let the plant store energy for next year. Pull (don't cut) stalks by grasping at the base and twisting. Each mature crown produces 2–5 kg of stalks per season. The plant is productive for 10-20+ years from a single planting. Divide crowns every 5-8 years to maintain vigor. Rhubarb is pest and disease free. The dramatic foliage adds visual interest to any growing area.
Notable varieties
| Cultivar | Type | Days | Notes |
|---|---|---|---|
| Victoria | heirloom | 730 | 1837 British heirloom. Green stalks with pink-red blush. Reliable, productive, the home garden standard. Less intensely colored than Crimson Red but more vigorous. |
| Crimson Red | open pollinated | 730 | Deep red stalks. Prettier in pies, slightly less productive than Victoria. The variety with the classic 'rhubarb pie' color. |
| Canada Red | open pollinated | 730 | Red stalks, sweet (the lowest oxalic acid of the common varieties). Late season, productive. |