How to Grow Serrano Peppers

serrano peppers

The Spruce / Gyscha Rendy

The flavorful Serrano pepper is getting plenty of culinary attention these days. Its name is a reference to the Sierra mountains in the Puebla and Hidalgo regions of Mexico where it is grown. They are also known as sweet peppers, chili peppers, or green chilis. They have a decent kick of intensity but are not ridiculously spicy. They are slightly hotter than a jalapeno and smaller in size, but with a sweeter flavor.

Serrano peppers are frequently eaten raw and added to salsa, pico de gallo, and many Mexican dishes. Like other peppers, this one is nutritious, with many vitamins, minerals, and dietary fiber. They are most commonly green, but can also be seen in hues of yellow, orange, red, brown or purple, and will start to change color as they begin to ripen.

Growing peppers can be somewhat trickier than other garden crops, but Serrano peppers are one of the easiest types to grow. They should be planted after the danger of frost has passed in the spring and will generally be ready to harvest within three months.

Scientific Name Capsicum annuum (cultivar 'Serrano')
Common Name Serrano pepper, green chile pepper
Plant Type Tropical perennial, or annual in cold zones
Mature Size 2-3 feet
Sun Exposure Full sun
Soil Type Rich, well-drained, loamy
Soil pH 5.5 to 7.0
Bloom Time Summer
Flower Color White
Hardiness Zones 10 and above, USDA
Native Areas Puebla and Hidalgo, Mexico

How to Plant Serrano Peppers

You can grow Serrano peppers from seed, or purchase plants from a nursery. It's best to buy them from a smaller farm vendor or trusted nursery. In big box stores, diseases can spread more quickly amidst large numbers of plants grown in industrial greenhouses. Choose the healthiest looking plants you can with no obvious signs of disease or injury.

Choosing proper plant companions in the garden is good for peppers. The best companions include other peppers, tomatoes, basil, parsley, carrots, parsnips, beets, garlic, onions, and radishes. Peppers do not do well planted near fennel or kohlrabi.

Plant your pepper plants 12 to 24 inches apart. If growing in containers, choose pots at least one gallon in size. Mature Seranno pepper plants may get up to five feet tall, but grown as an annual they're more likely to stay between two and three feet tall.

You may want to stake your plants so they don't droop when the peppers are close to ripening. Use something soft to tie them, like nylons (pantyhose) or pieces of cotton jersey.

Rotate your pepper plantings every year, and don't plant them where other nightshades have been planted in the previous two years.

Serrano Pepper Plant Care

Light

Peppers, being a tropical plant, need a full sun position to thrive. At least six hours of sun a day is ideal. Even after they have been picked, they should still be placed in the sun to ripen in the green stage.

Soil

The Serrano, like all peppers, likes a soil that is rich, fertile, well-drained, and neutral to slightly acidic.

Adding compost is key for creating the rich soil they love. Some aficionados like to adjust the pH of their soil to grow peppers with more intense heat.

Water

Water your pepper plants regularly, right after fertilizing, and whenever the soil feels dry. Water at the base of the plant instead of from above, to help prevent mildew.

Temperature and Humidity

Because most peppers originate in warm climates free of frost, they are considered a tropical perennial, but they're mostly grown in the United States as annuals.

Fertilizer

Fertilizing your pepper plants regularly, about once per month, throughout the growing season will also help them perform well.

serrano peppers
The Spruce / Gyscha Rendy
serrano peppers
The Spruce / Gyscha Rendy
serrano peppers
The Spruce / Gyscha Rendy

Harvesting

It's recommended to pick your Serrano peppers while they are still green. They will ripen to red on the vine but they also become more susceptible to rot the longer they are left. Cut them gently, rather than pulling them, so as not to injure the tender stems.

If you want them to ripen more, some people prefer these more mellow, slightly sweeter flavors, just place them in a bowl in a cool dry place with indirect sunlight.

How to Grow Serano Peppers From Seed

It is relatively easy to grow these peppers from seed. It is best to start them indoors around two months before the last expected frost of the spring. Sowing them in peat pots works well for when you then transfer them outside.

The seeds need a decent amount of warmth for germination, preferably around 80—85 degrees Fahrenheit and plenty of sunlight. Don't sow them too deep—around 1/4 inches is ample. Make sure the growing medium is well-drained and moist.

Gradually exposing your seedlings to outdoor temperatures can help to prevent shock and it is best to wait until temperatures are at least 60 degrees Fahrenheit during the day before attempting to transplant them.

Common Pests and Diseases

Luckily peppers are more resistant to pests than other plants, which means it's easy to grow them organically. But, being nightshades (like potatoes and tomatoes), they may develop various problems, including an infestation of cutworms, aphids or whiteflies. These can be removed by hand or by blasting them with a spray of water using the shower position on your hose nozzle, or by using a natural soap spray.

Planting in full sun, rotating your plantings each year to replenish the soil, and adhering to companion planting rules can help alleviate many of these problems.