Swiss chard
Beta vulgaris subsp. cicla
Also known as: Silverbeet, Chard, Spinach beet, Seakale beet, Perpetual spinach, Mangold, Acelga, Bette à carde
Quick facts
- Category
- leafy greens
- Difficulty
- beginner
- Days to harvest
- 50 to 65 days
- Harvest type
- cut leaves, plant regrows for repeated harvests
- Spacing
- 30 cm between plants
Environment
- Temperature
- 10–24°C
- pH
- 6 to 7
- EC (hydroponic)
- 1.8 to 2.5 mS/cm
- Daily light
- 14 to 18 mol/m²/day
Climate and zones
- USDA zones
- 5 to 10 (winter low around -29°C or warmer)
- Frost tolerance
- frost hardy (handles regular frost)
- Season
- cool (spring and fall crops)
Viable growing environments:
- outdoor year-round (in zone)
- outdoor in growing season (annual)
- unheated greenhouse / hoop house
- heated greenhouse
- indoor (heated home)
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Swiss chard works in:
- deep water culture (rafts)
- NFT channels
- media bed (ebb and flow)
- wicking bed
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (swiss chard works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Net pot, no medium (Bare-root) | - | - | - |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.8 |
| vegetative | 3 | 1 | 2 | 2 |
Companion-growing notes
- Heavy uptake of calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
One of the easiest and most productive hydroponic leafy greens, with the bonus of dramatic visual appeal from the colorful stalks. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 12–28°C (wider tolerance than spinach; produces through summer and mild winters). Moderate light (DLI 14-20 mol/m2/day). Any hydroponic system works (NFT, DWC, media beds). From transplant to first harvest: 5-7 weeks. Harvest outer leaves (cut-and-come-again) while the center continues producing new leaves. A single plant provides harvests every 1-2 weeks for 3-6 months, making chard one of the longest-producing individual plants in any hydroponic system. 'Rainbow' or 'Bright Lights' chard adds color that sells at farmers' markets ($4-8/bunch). The colorful stalks are excellent pickled: quick-pickle with vinegar, sugar, and spices for a stunning, flavorful condiment.
Verified against: rhs-uk, cornell-controlled-environment-ag. Last reviewed 2026-05-15.