In a sheltered, sunny spot, jalapenos bear peppers summer through fall, and overwintering plants for a second year of spicy fruit is a temptation. These cultivars of Capsicum annuum are usually grown as annuals, but they're perennial in U.S. Department of Agriculture plant hardiness zones 9 through 11. In colder climates, jalapenos can survive winter when placed in a bright, airy, frost-free spot indoors.
Overwintered jalapenos can suffer from diseases and other problems. Root rots sometimes infect jalapenos experiencing cold temperatures and low light levels, and pests such as aphids can overwinter on plants. Growth slows when nighttime temperatures fall below 60 F. Jalapenos infected by viruses during their first growing season must be destroyed at the end of the year to avoid the spread of diseases. Because jalapeno seeds germinate well and plants produce fruit in their first year, growing new plants each season often requires less effort than caring for plants through the winter.
High light levels, shelter and reduced watering can help jalapenos overwinter successfully. Heavy rain and cold temperatures can damage plants growing outdoors, even in warm climates, so erect a sturdy, clear plastic shelter over plants growing in the ground, and open it daily when the weather is fine to allow condensation to evaporate. Jalapenos in containers can overwinter indoors in a bright area such as a home greenhouse, conservatory or south-facing, sunny windowsill. Water plants only when the top 1 inch of soil is dry to avoid damping off diseases, and don't apply fertilizer, because the plants grow little in winter.
Jalapenos begin growing when temperatures and daylight hours rise in spring. Check plants every three or four days from midspring onward, and increase watering when new foliage appears so that the potting soil is constantly moist but not sodden. Apply a high-potassium fertilizer, such as a soluble 18-18-21 product diluted at a rate of 1 tablespoon per gallon of water, or according to the manufacturer's instructions, every two weeks. Jalapenos can be placed outdoors when nighttime temperatures are above 55 F. Place plants outdoors during the day and bring them inside at night for one week before putting them outdoors permanently in a full-sun site. Alternatively, grow jalapeno plants indoors in a very bright area.
Overwintered jalapenos might require special care during spring. Prune any dead or diseased plant tissue, disinfecting your pruning shears before and after use with household disinfectant, and check plants for pests such as aphids clustered on the undersides of leaves. Spray infestations with a ready-to-use insecticidal soap, covering all plant parts, in the morning or evening. Repeat applications weekly as needed. Plants can grow thin and leggy in low light levels, but pinching out the ends of growing stems encourages bushiness and sturdier growth. Stop fertilizing jalapenos at midsummer to encourage fruit formation.
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