Bell pepper / Sweet pepper (Capsicum annuum) growing guide

Quick facts

Category: fruiting
Difficulty: intermediate
Days to harvest: 80 to 120 days
Harvest type: continuous production over weeks or months
Spacing: 50 cm between plants

Environment

Temperature: 20–30°C
pH: 5.5 to 6.5
EC (hydroponic): 1.8 to 2.8 mS/cm
Daily light: 22 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

Bell pepper works in:

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

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 (bell pepper 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
Rockwool (Mineral wool)	alkaline until pre-soaked	very high	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	2
flowering	2	2	3	2.3
fruiting	1	2	4	2.6

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.
High transpiration. Reservoir level will need regular top-ups during fruiting or flowering.

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 premier hydroponic crop with well-established commercial protocols. Dutch bucket, drip-to-waste, or rockwool slab systems are standard for commercial production. EC 2.0-3.5 mS/cm (increase gradually as plants mature and begin heavy fruiting). pH 5.5-6.5. Temperature: 21–28°C daytime, 16–18°C night (the day-night differential is important for fruit set). Very high light demand (DLI 20-30 mol/m2/day; bell peppers need strong light to produce thick walls and large fruit). Train plants to 2-4 leaders using the Spanish or Dutch pruning method: allow 2-4 main stems at the first fork and remove all other suckers. Support with string or stakes. Calcium supplementation prevents blossom end rot. Increase potassium during heavy fruiting for better color development and wall thickness. Green-stage harvest: 60-75 days from transplant. Red-stage harvest: 80-100 days. Each plant produces 8-15 fruits per cycle. Common issues: blossom drop (caused by temperature extremes or poor pollination; shake plants gently to release pollen in indoor systems), aphids, and thrips. Bell peppers are one of the highest-value hydroponic vegetables, commanding $4-8/kg retail.

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	Breeder / origin	Days	Size	Notes
California Wonder	open-pollinated		75	200 g	Pre-1928 open-pollinated standard. Blocky four-lobed green-to-red fruit. Tolerates a wide climate range; the default bell pepper for most US home growers. Average yield, average flavor, very reliable.
King of the North	open-pollinated		70	180 g	Cool-climate selection. Sets fruit at lower temperatures than most bells; produces useful yields in zones 4-6 where California Wonder struggles. Green-to-red.
Big Red	hybrid	Burpee	75	300 g	F1 producing very large 8-10cm thick-walled fruit. Higher yield than open-pollinated bells. Green-to-red. Disease resistance to Tobacco Mosaic Virus.
Lipstick	open-pollinated		70	150 g	Pimento-style sweet pepper. Smaller than bells, thicker walls, sweeter flavor. Ripens dependably red even in cooler zones. Excellent fresh or roasted.
Jimmy Nardello	heirloom		80	90 g	Italian frying pepper, not a bell despite often being grouped with them. Long thin red fruit, very sweet when fully ripe. Slow Food Ark of Taste listed; one of the best frying peppers in any climate.