Parsnip

Quick facts

Category

roots bulbs

Difficulty

intermediate

Days to harvest

100 to 180 days

Harvest type

single harvest then replant

Spacing

10 cm between plants

Environment

Temperature

4–22°C

pH

6 to 7

EC (hydroponic)

1.4 to 1.8 mS/cm

Daily light

14 to 22 mol/m²/day

Climate and zones

USDA zones

2 to 9 (winter low around -46°C or warmer)

Frost tolerance

very hardy (survives deep cold)

Season

cool (spring and fall crops)

Viable growing environments:

• outdoor year-round (in zone)
• outdoor in growing season (annual)
• unheated greenhouse / hoop house

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

Parsnip works in:

• 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 (parsnip works in the media listed below).

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.

Companion-growing notes

• Heavy uptake of potassium. 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

A deep-rooted crop requiring substantial growing medium depth. The taproot grows 20–35 cm long (some varieties exceed 40 cm), requiring deep media beds or very tall containers (40 cm of loose, stone-free substrate). Any obstruction or compaction causes forking. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 10–22°C (cool-season; heat above 25°C causes poor root quality). Moderate light (DLI 12-18 mol/m2/day). Long season: 100-130 days from seed. Direct seed (parsnips do not transplant well because the taproot is the product). Seed viability declines rapidly; use fresh seed from the current season. Germination is slow (2-3 weeks at best, sometimes longer). Thin seedlings to 8–10 cm spacing. Frost exposure before harvest genuinely improves sweetness. Short-rooted varieties ('Gladiator', 'Lancer') are more practical for shallower media beds than traditional long-rooted types. The tops are mildly toxic (they can cause phytophotodermatitis, a skin reaction when sap contacts skin in sunlight); wear gloves when handling foliage.

Further reading

• Best crops for hydroponic beginners
• The Kratky method: grow lettuce with zero electricity