PL. —Capsicum annuumBotanical illustration — drop image
Capsicum annuum

Jalapeño

SummerFall
4a11bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
Peak bloom
Fall
Not in bloom
Peak bloom
In bloom
Background

Jalapeño is a medium-heat chili pepper (Capsicum annuum) grown as a warm-season annual in upstate New York. It produces firm green fruits that ripen to red, rating 2,500–8,000 Scoville heat units. Gardeners grow it for reliable yields in containers or beds and a long harvest window from midsummer to frost.

Peppers need warm soil and a long season, so start seeds indoors 8 weeks before the last frost and transplant only after soil reaches 65°F. Plants are frost-sensitive and slow in cool weather; black plastic mulch or a warm microclimate improves results. Consistent watering and moderate nitrogen prevent blossom drop and blossom-end rot. Harvest green for milder flavor or red for sweeter, hotter fruit.

Capsaicin, the compound responsible for heat, is used topically in formulations for muscle and joint pain and neuropathic pain. Peppers are a documented source of vitamin C and are widely used culinarily fresh, pickled, or smoked and dried as chipotle.

Care guide
SunFull sun; 8+ hours
WaterRegular; consistent moisture once fruiting begins
SoilRich, well-draining, slightly acidic (pH 6.0–6.8)
Spacing14–18 inches
Height24–30 inches
Zone4a – 11b
Seasonal tasks
summer
cutHarvest when firm and dark green; red jalapeños are fully ripe and slightly sweeter
Common problems

Blossom End Rot

Symptoms

Sunken, dark leathery patch on the bottom end of the fruit. Caused by calcium uptake disruption from uneven watering.

Treatment

Maintain consistent soil moisture and mulch. Avoid overfertilizing with nitrogen. Test soil and amend calcium if deficient.

Bacterial Soft Rot

Symptoms

Rhizomes turn mushy and foul-smelling; foliage yellows and pulls away easily at the base. Often follows borer damage or overly wet soil.

Treatment

Cut away all soft tissue back to firm rhizome, let it dry, and dust the cut with sulfur. Improve drainage and avoid burying rhizomes. Destroy badly infected plants.

Mosaic virus

Symptoms

Yellowing, mottled, or distorted leaves. No cure — spread by aphids.

Treatment

Remove and destroy infected plants. Control aphid populations to prevent spread. Do not propagate from infected tubers.

Aphids

Symptoms

Clusters of small soft insects on new growth and flower buds.

Treatment

Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.

Flea Beetle

Symptoms

Small round shot-holes scattered across leaves; tiny dark beetles that jump when disturbed. Heavy feeding stunts young plants.

Treatment

Use floating row covers on seedlings. Remove crop debris and weeds that harbor beetles. Apply kaolin clay or spinosad if damage is severe.

Phytophthora Root Rot

Symptoms

Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.

Treatment

Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.

Pepper Anthracnose Fruit Rot

Symptoms

Sunken, circular lesions on ripening fruit with concentric rings and pink or black spore masses in the center. Spreads quickly in warm, wet weather.

Treatment

Remove and destroy infected fruit. Avoid overhead watering and improve airflow with proper spacing. Rotate away from peppers and tomatoes for 2–3 years. Use disease-free seed and apply copper-based fungicide preventively in wet seasons.