How to Grow Serrano Peppers

serrano peppers

The Spruce / Gyscha Rendy

The flavorful serrano pepper (Capsicum annuum 'Serrano') is a cultivar of the Capsicum annuum species, which also includes jalapeños, cayenne peppers, bell peppers, and more. Serranos have a decent kick but are not ridiculously spicy. The fruits are around 3 to 3.5 inches long. They are most commonly green but can also be seen in hues of yellow, orange, red, brown, or purple as they 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 in the spring and will generally be ready to harvest within three months. Be aware that the leaves, seeds, and fruits of the plants contain capsaicin, a compound that creates a burning sensation and is technically toxic to people.

Common Name Serrano pepper
Botanical Name Capsicum annuum 'Serrano'
Family Solanaceae
Plant Type Perennial, vegetable
Size 2–3 ft. tall, 1.5 ft. wide
Sun Exposure Full sun
Soil Type Loamy, moist, well-drained
Soil pH Acidic, neutral (5.5 to 7)
Bloom Time Summer
Hardiness Zones 9–11 (USDA)
Native Areas Central America
Toxicity Toxic to humans

How to Plant Serrano Peppers

When to Plant

Plant serrano peppers in the spring after the threat of frost has passed. Night temperatures should be reliably above 55 degrees Fahrenheit. Seeds also can be started indoors six to eight weeks prior to your area's projected last frost date in the spring.

Selecting a Planting Site

Pick a sunny garden spot with rich soil that has good drainage. Container growth is also an option. 

Moreover, 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 don't do well planted near fennel or kohlrabi. Furthermore, rotate your pepper plantings every year, and don't plant them where other members of the nightshade (Solanaceae) family have been planted in the previous two years, as the plants tend to share the same pests and diseases.

Spacing, Depth, and Support

Sow seeds roughly 1/4 inch deep, and position nursery plants at the same depth they were growing in their previous container. Space plants 1 to 2 feet apart in rows around 18 inches apart. You might want to stake your plants, so they don't droop when the peppers are close to ripening.

Serrano Pepper Plant Care

Light

Being a tropical plant, serrano peppers need full sun to thrive. At least six hours of direct sunlight per day is ideal.

Soil

These peppers need an organically rich, well-draining soil. A slightly acidic to neutral soil pH is best. Adding about an inch of compost at the time of planting is key for creating the fertile soil they love.

Water

Soil that’s consistently moist but never soggy is ideal for growing serrano peppers. Water whenever the soil feels dry 1 to 2 inches down, but don’t allow the plants to become waterlogged. Also, water at the base of the plants instead of from above to help prevent mildew.

Temperature and Humidity

Serrano peppers do best in a warm, humid environment. They are frost-sensitive and are often grown as annuals outside of their native tropical climate. Temperatures above 75 degrees Fahrenheit are optimal. In warmer weather, check regularly to make sure they are getting enough water.

Fertilizer

These plants are heavy feeders. Fertilize at the time of planting and then throughout the growing season. Use a balanced vegetable fertilizer, following label instructions.

Pollination

Pepper plants are self-pollinating with the help of wind and animals. You can also gently shake your plants to aid in pollination.

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

Types of Serrano Peppers

There are several serrano varieties, including:

  • 'Serrano Del Sol': This variety boasts large peppers and is notoriously prolific. 
  • 'Serrano Purple': The peppers on this plant mature to a purple color and are slightly longer than the main cultivar. 
  • 'Serrano Tampiqueno': These peppers are notably hot and flavorful, and they grow in a distinctive club shape.

Serrano Peppers vs. Jalapeño Peppers

Serranos and jalapeños are cultivars within the same species. And being closely related, they are often mistaken for one another. They are quite similar in appearance and flavor. However, serranos are slightly smaller and pack more heat than jalapeños. 

Harvesting Serrano Peppers

Serrano peppers will generally be ready to harvest in around 80 days, though this can slightly vary depending on the type. Wait until the peppers have reached their mature size for the best flavor. It’s recommend to harvest when the peppers are still green, rather than allowing them to ripen to red or another color, as they become more susceptible to rot the longer they stay on the vine. 

Use shears to cut them off the vine rather than pulling them to avoid injuring the tender stems. Wear gloves when handling the plants and avoid touching your face to protect your skin from the capsaicin. You can store your peppers in the fridge for up to a week and use them fresh or cooked.

How to Grow Serrano Peppers in Pots

If you don’t have the garden space for growing serranos, a container is a great alternative. Plus, you can easily move a container into the sun to ensure your plant is getting enough light. A 3-gallon container is ideal. A plant will survive in something slightly smaller, but its output will likely be diminished. Make sure the container has ample drainage holes. Unglazed clay is a good material to allow excess soil moisture to escape through its walls. 

Pruning

For the most part, pruning won’t be necessary. If suckers start growing around the plant’s base, trim them off to allow the plant to focus its energy on the primary stems that will bear the most fruit. Also, pinch off any blossoms that appear early in the season to let the plant focus its energy on growth before it bears fruit.

Propagating Serrano Peppers

Seeds or nursery starts are the most common way to grow serranos. But it’s also possible to propagate them via cuttings. Cuttings allow you to essentially clone a plant, so you can take them from a serrano plant you like—potentially for its taste or fruit production. The best time to do this is in the early summer. Here’s how:

  1. Cut a 4- to 6-inch piece of healthy stem just below a leaf node.
  2. Remove any leaves on the lower half of the cutting, and pinch off any flowers.
  3. Apply rooting hormone to the cut end.
  4. Plant the stem in a moist soilless potting mix. Use a biodegradable peat pot that can be planted directly in the soil or a container. 
  5. Keep the cutting in a warm spot with indirect, bright sunlight. And keep the soil moist but not soggy.
  6. There should be root growth in a couple weeks. Test this by gently tugging on the stem to check for resistance. 

How to Grow Serrano Peppers From Seed

It is relatively easy to grow these peppers from seed. If you are starting them in containers, use peat pots to avoid disturbing the growing seedlings once you move them to their eventual planting site. Add three seeds to each pot filled with moist soilless potting mix, and lightly cover them in soil. Thin them to one plant per pot after germination.

The seeds need a decent amount of warmth for germination, preferably around 80 to 85 degrees Fahrenheit, as well as plenty of sunlight. Make sure the growing medium remains moist but has good drainage. The seeds should germinate in about two weeks.

Potting and Repotting Serrano Peppers

A potting mix that’s rich and well-draining is ideal for growing serrano peppers. One that’s formulated for vegetables is often sufficient. It’s best to plant your serranos in a container that will hold their mature size to avoid having to repot and disturb their sensitive roots. Water well after potting. And check the container's moisture level often, as potted plants generally dry out faster than those grown in the ground.

Overwintering

If you don’t live within the serrano pepper’s growing zones, it is possible to bring a potted plant indoors to overwinter. Make sure to do so prior to any threat of frost in the fall forecast. Keep your plant by the brightest window you have, preferably a south-facing one. And water when the top inch of soil dries out. Also, be sure to protect the plant from drafts and drying air from heating vents.

Common Pests and Plant Diseases

Peppers typically don’t have as many pest and disease issues as other members of the nightshade family. But certain issues still might arise. Common pests include cutworms, aphids, and whiteflies. These can be removed by blasting them with a garden hose spray or using a natural insecticidal soap. Moreover, verticillium wilt is a common disease that causes yellowing and wilting of the foliage. Practicing crop rotation and treating pest and disease issues promptly are some of the best tactics to keep your garden healthy.

FAQ
  • Are serrano peppers easy to grow?

    Serrano peppers are fairly easy to grow as long as they get enough sunlight, moisture, and nutrients.

  • How long does it take to grow serrano peppers?

    Serrano peppers will typically be ready to harvest within three months of planting.

  • Do serrano peppers come back every year?

    In hot climates, serranos are perennial. Gardeners outside of their growing zones often treat the peppers as an annual and start with new plants each year.

Article Sources
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  1. Capsicum Annuum (Longum Group) (Cayenne Pepper, Chili Pepper, Hot Pepper) | North Carolina Extension Gardener Plant Toolbox. https://plants.ces.ncsu.edu/plants/capsicum-annuum-longum-group/.