Zucchini / Courgette (Cucurbita pepo) growing guide

Quick facts

Category: fruiting
Difficulty: beginner
Days to harvest: 45 to 60 days
Harvest type: continuous production over weeks or months
Spacing: 60 cm between plants

Environment

Temperature: 18–30°C
pH: 6 to 7
EC (hydroponic): 1.8 to 2.4 mS/cm
Daily light: 20 to 30 mol/m²/day (strict, will fail outside this range)

Climate and zones

USDA zones: 10 to 13 (winter low around -1°C or warmer)
Frost tolerance: frost sensitive (dies at first frost)
Season: warm (summer crops, frost-sensitive)

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

Zucchini works in:

media bed (ebb and flow)
wicking bed
soil bed
drip / Dutch buckets

Root mass is heavy - thin-channel systems (NFT, vertical towers) can't hold this crop mechanically, hence the system list above.

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 (zucchini works in the media listed below).

Medium	pH effect	Water retention	Bacterial surface
Expanded clay pebbles (LECA)	neutral / inert	low	high
Coco coir (Coconut coir)	slightly acidic	high	moderate
Perlite (Expanded volcanic glass)	neutral / inert	very low	low
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	1
vegetative	3	1	2	1.9
flowering	2	2	3	2.1
fruiting	1	2	4	2.2

Companion-growing notes

Heavy uptake of potassium, calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
Very high transpiration. Reservoir level drops fast once the plant is mature; expect daily top-ups and watch for EC creeping up as water evaporates faster than salts.

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 highly productive hydroponic crop. Large container (20 L) or media bed. EC 2.0-3.0 mS/cm. pH 5.5-6.8. Temperature: 20–30°C. High light (DLI 18-28 mol/m2/day). Plants are large and need space. Hand-pollination required indoors: transfer pollen from male flowers (thin straight stem, no fruit swelling at base) to female flowers (small fruit swelling at the base) using a paintbrush. From transplant to first harvest: 45-55 days (one of the fastest fruit-bearing crops). Harvest every 1-2 days at 15–20 cm; leaving oversized zucchini on the plant slows production. Powdery mildew is the most common disease; resistant varieties and good airflow help. The prolific production makes zucchini one of the best-value hydroponic crops for home growers. The edible flowers are a bonus harvest: pick male flowers in the morning when fully open. For squash blossom preparation: stuff with a mixture of ricotta, mozzarella, and a single anchovy fillet, dip in a light batter, and fry until golden.