Jalapeños are a pod type of capsicum annuum. The growing period is 70–80 days. When mature, the plant stands 70–90 cm (28–35 in) tall. Typically, a plant produces 25 to 35 pods. During a growing period, a plant will be picked multiple times. As the growing season ends, the peppers turn red, as seen in Sriracha sauce. Jalapeños thrive in a number of soil types and temperatures, though they prefer warmer climates, provided they have adequate water. The optimum temperature for seed germination is 29 °C (84 °F), with degradation of germination seen above 30 °C (86 °F) and little to no germination occurring at 40 °C (104 °F); at 29 °C (84 °F) the time to 50% germination rate depends on cultivar and seed lot but was tested as being between 4 to 5 days, which is shorter than Cayenne. A pH of 4.5 to 7.0 is preferred for growing jalapeños and keeping the soil well drained is essential for keeping the plants healthy. Jalapeños need at least 6 to 8 hours of sunlight per day. Experimental results show that unlike bell peppers at least 7.5 milliMoles (mM) Nitrogen is needed for optimal pod production and 15 to 22 mM Nitrogen produces the best result, the plant produces both more leaves and more pods, rather than just more leaves. Once picked, individual peppers may turn to red of their own accord. The peppers can be eaten green or red. Though usually grown as an annual they are perennial and if protected from frost can produce during multiple years, as with all Capsicum annuum.
Jalapeños are subject to root rot and foliar blight, both often caused by Phytophthora capsici; over-watering worsens the condition as the fungus grows best in warm wet environments, however the cause is not itself over-watering but the fungus. Crop rotation can help, and resistant strains of jalapeño, such as the NuMex Vaquero and TAM Mild Jalapeño, have been and are being bred as this is of major commercial impact throughout the world. As jalapeños are a cultivar the diseases are common to capsicum annuum: Verticillium wilt, Cercospora capsici, Powdery mildew, Colletotrichum capsici (Ripe Rot), Erwinia carotovora (Soft Rot), Beet curly top virus, Tospovirus (Tomato spotted wilt virus), Pepper mottle virus, Tobacco mosaic virus, Pepper Geminiviridae, and Root-knot nematode being among the major commercially important diseases
After harvest if jalapeños are stored at 7.5 °C (45.5 °F) they have a shelf life of up to 3–5 weeks. Jalapeños produce 0.1-0.2 µl/kg⋅h of ethylene which is very low for chiles and do not respond to ethylene treatment. Holding jalapeños at 20-25 °C and high humidity can be used to complete the ripening of picked jalapeños. A hot water dip of 55 °C (131 °F) for 4 minutes is used to kill off molds that may exist on the picked peppers without damaging them. The majority of jalapeños are wet processed, canned or pickled, on harvesting for use in mixes, prepared food products, and salsas.