Cilantro / Coriander (Coriandrum sativum) growing guide

Quick facts

Category: herbs soft
Difficulty: intermediate
Days to harvest: 45 to 60 days
Harvest type: cut leaves, plant regrows for repeated harvests
Spacing: 15 cm between plants

Environment

Temperature: 10–22°C
pH: 5.5 to 6.7
EC (hydroponic): 1 to 1.5 mS/cm
Daily light: 12 to 16 mol/m²/day

Climate and zones

USDA zones: 3 to 11 (winter low around -40°C or warmer)
Frost tolerance: tolerates light 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

Cilantro works in:

deep water culture (rafts)
NFT channels
vertical / aeroponic tower
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 (cilantro 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	0.6
vegetative	2	1	2	1.3

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 most commonly grown hydroponic herbs, but also one of the most frustrating due to rapid bolting. EC 1.0-1.8 mS/cm. pH 6.0-7.0. Temperature: 10–22°C (critical: above 24°C, cilantro bolts within days, producing flowers instead of the leafy growth you want). Low to moderate light (DLI 12-16 mol/m2/day; excessive light and heat accelerate bolting). NFT, DWC, Kratky, and raft systems all work. From seed to first leaf harvest: 3-4 weeks (baby) or 5-6 weeks (full-sized). Succession plant every 2 weeks for continuous supply because each planting's productive leaf-harvest window is only 2-3 weeks before bolting. Slow-bolt varieties ('Calypso', 'Long Standing', 'Santo') extend the leaf harvest by 1-2 weeks. If the plant bolts, you can either harvest the green seeds (which have a bright, citrusy flavor used in some cuisines) or let them dry for coriander seed. The taproot does not transplant well; direct seed into the final growing position. For commercial hydroponic herb growers, cilantro is a high-volume, high-demand crop that requires disciplined succession planting to maintain consistent supply.

Notable varieties

A starting shortlist of cultivars worth knowing about. Not exhaustive: the seed catalogs list hundreds of named varieties. These are the ones home growers commonly choose between.

Cultivar	Type	Days	Notes
Santo	open-pollinated	45	The slowest-bolting standard cilantro. Good leaf-yield window before flowering, around 4-6 weeks under spring conditions. Succession-plant every 2-3 weeks for continuous harvest.
Calypso	open-pollinated	50	The slowest-bolting cilantro available, holds in leaf 3 weeks longer than Santo before flowering. Compact habit (35cm), suits containers. Pricier seed but worth it for summer growing.
Confetti	open-pollinated	50	Feathery dill-like foliage rather than the standard parsley-shaped cilantro leaf. Same flavor. Bolt timing similar to Santo. Useful as an ornamental cilantro in mixed plantings.