Knowing when fruit and vegetables are at their peak of ripeness can be a challenge for home gardeners. This is especially true with crops such as peppers that don't change dramatically when ripe. The signs that jalapenos are ready to pick are subtle but distinct.
From Planting to Harvest
Jalapenos are a warm-weather crop and should not be planted outside until night temperatures stay above 50 degrees Fahrenheit. Make a note of your planting date so that you know when to start looking for ripe fruit. Transplants produce mature fruit in 70 to 85 days, but when started outdoors directly from seed, jalapenos don't bear ripe fruit for 100 to 120 days after planting. Because of this long wait time, many gardeners either start their plants indoors four to six weeks before their anticipated planting date or buy plants from garden centers. The actual number of days to harvest depends on the cultivar selected, cultural practices and weather conditions.
Jalapenos are usually picked when ripe but still green. Ready-to-pick fruit exhibit lines or small cracks on the shoulder, the curved area just under the stem, and sometimes darkened areas on the skin that indicate the fruit is about to change color. The skin should be smooth and shiny. Mature jalapenos are usually 2 to 3 1/2 inches long, but size depends on cultivar.
Letting jalapenos turn red doesn't increase their hotness but does result in softer-textured fruit with a higher vitamin content. Jalapenos allowed to change color on the vine don't last as long fresh as when they're picked green, so plan on using them within about a week or can them.
What to Avoid
Look for fruit with firm, smooth skin (except for the cracks on the shoulders) and solid stems. Discard jalapenos with soft, watery spots, or with punctured or wrinkled skin. These fruits are damaged or past their prime.
At the End of the Season
The first frost will kill your jalapeno plants, so pick all the remaining fruit, regardless of size when a frost is forecast. Even the immature fruit are tasty. Alternatively, pull the entire plant and hang it upside down in a protected spot; some of the fruit will continue to ripen.