Essential guide to growing jalapenos (from seed to harvest)

Jalapeno peppers are a home gardener favorite as they mix the best of two worlds. On the one hand, jalapenos bring some heat and attitude; but the peppers are also versatile and easy to use in the kitchen.

And this mix of heat and ease of use has us growing jalapenos yearly.

Growing jalapenos from seed quick guide:
1. Plant seeds on moist potting soil and press to ensure contact between seed and soil
2. Mist with a spray bottle and cover with plastic wrap with holes for air circulation
3. Place in a warm location (20-25 Celsius / 68-77 Fahrenheit) with plenty of light
4. Move to a slightly cooler location with good light when seeds germinate, and you see the first leaves
5. Harden off and move outdoor when there is no longer any risk of frost

Choose to buy jalapeno pepper plants at your local garden center or start your plants from seeds early in the spring.

And this is key; start early as peppers need time to mature and develop.

Starting jalapeno peppers from seed

We grow jalapenos from seeds every year. We grow most jalapeno pepper plants in pots or DIY grow bags, but they can, of course, be transplanted outdoors when there is no longer a risk for frost.

1: When to plant jalapeno peppers indoors

Start seeds 8-10 weeks before the last expected frost. Some will argue that 6-8 weeks is sufficient, but as pepper plants are not cold hardy, we prefer starting seeds early.

For reference, we grow in zone 7 and are usually frost-safe in early May.

2: Select pot and potting mix

Use seed starter trays with a plastic cover or a regular starter pot and plastic wrap. Make sure you make small holes in the plastic wrap to ensure good air circulation.

Use regular potting soil or a soilless seed starting mix. Make sure your chosen medium holds moisture and drains well.

3: Plant the jalapeno seeds

Plant jalapeno seeds shallow and press seeds lightly to ensure contact between seed and soil.

If you are unsure of seed quality, choose to pre-germinate your jalapeno seeds.

Mist the seeds using a spray bottle and place the covered pots in a spot with good light and a temperature around 25 degrees Celsius / 77 degrees Fahrenheit.

Keep soil moist but never soaking wet. Seeds will rot if sat in constantly soaking wet soil.

Seeds will typically germinate in 14-21 days. When seeds sprout and you see first leaves, remove the cover and move the pot to a slightly cooler spot (20-22 degrees Celsius / 68-72 degrees Fahrenheit) with a minimum of 8 hours of sunlight.

Growing jalapeno peppers often means starting seeds indoors early in the year when there are insufficient levels of natural light. For the best result, use grow lights and give your young plants indoors 16 hours of artificial light followed by 8 hours of darkness and rest.

4: Transplant jalapeno seedlings

Your jalapeno pepper plants are ready to be transplanted into slightly bigger pots (10 cm / 4 inch) when the seedlings have developed their 3rd set of true leaves.

To protect against transplant shock, place seedlings in a spot with no direct sunlight for 2-4 days.

When the jalapeno plant seems stable, move to a spot with a minimum of 8 hours of natural light per day.

Your seedlings will grow leggy and spindly if you do not provide enough light.

5: Move the jalapeno pepper plant to a larger pot

Leave the jalapeno pepper plants in their pots as long as you can. But when you see roots growing through the pot’s drainage holes, it is time to move the jalapeno peppers to a larger pot.

When potting up jalapeno peppers, you can plant the stem slightly deeper than it was growing before.

But do not bury the stem like you would with a tomato plant.

And if you are unsure, plant at the same depth as the seedling was growing before.

How to care for jalapeno peppers

Jalapeno pepper plants thrive in well-draining soil with a lot of organic matter.

Jalapeno plants want full sun and are not very cold hardy. Mature developed plants want plenty of water and a temperature between 20-22 degrees Celsius / 68-72 degrees Fahrenheit.

Do not expose the plant to extreme heat as temperatures above 30 degrees Celsius / 86 degrees Fahrenheit may hurt fruit production.

Healthy plants are typically quite resistant to pests and diseases. But plants exposed to humid conditions, extreme heat, or lack of water will get stressed and are more susceptible to infections.

Aphids, fungal diseases, and hornworms are some common pests and diseases that attack jalapeno pepper plants. Other problems include yellowing pepper leaves and fungus gnats.

Yellowing pepper leaves
Yellowing pepper leaves – unwanted but beautiful

Careful manual inspection, spraying leaves with water, and water-based neem oil solutions are great methods to protect your plants safely.

Propagating or growing jalapeno peppers from cuttings?

Growing jalapenos from cuttings are excellent if you have a plant you want to clone for the next growing season.

Reasons to propagate peppers from cuttings include:

  • cloning a plant that has proven to be disease resistant
  • over-wintering pepper plants that have given you bumper crops
  • transferring pepper plants to hydroponic grow systems

The process is straightforward, but the rooting process is slow, where you may have to wait for two months or more.

Propagate jalapeno pepper plants from cuttings in 7 steps

  1. Find a young green branch that is still growing; you do not want a woody stem.
  2. Using sharp garden scissors, cut the green stem at a 45-degree angle.
  3. Trim all flowers, buds, and fruits, leaving only a few leaves at the top (4-5)
  4. Place pepper seedling in a glass with room temperature water.
  5. Place glass in a spot with plenty of indirect light but no direct sunlight
  6. Replace water as needed at least twice per week
  7. When roots form, plant cutting in soil or your hydroponic grow system

How to harvest jalapenos

Jalapeno peppers can be harvested early when green or left to ripen on the plant.

Jalapeno peppers will change from light green to dark green, then almost black before reaching their mature red color.

Generally speaking, jalapeno peppers should be firm to the touch and be approximately 8-10 cm / 3-4 inches long when they are ready for harvest.

If you are patient, wait for the jalapeno peppers to show superficial stress marks on the skin (corking). This condition, corking, is entirely safe and indicates that your jalapeno peppers are ready to be harvested.

Jalapeno pepper with the tell tale signs of corking
Jalapeno pepper with the tell tale signs of corking
Corking happens when the skin grows slower than the inside, or flesh, of the jalapeno pepper. Corking can happen or all varieties of peppers, but I have only seen it on jalapenos in our gardens.

Harvest fresh peppers using sharp garden scissors, or push the fruit towards the main branch until it snaps off.

How to preserve jalapeno peppers

Jalapeno peppers are, of course, best when sliced thinly and eaten fresh or lightly pickled.

But growing jalapenos peppers, come harvest time, you will have more peppers than you will be able to eat and use fresh.

But luckily, there are two great and easy ways to preserve jalapeno peppers.

Use your jalapeno peppers to make a hot sauce.

Dry peppers in the oven

  1. Wash and dry peppers
  2. Remove stalks and slice jalapeno peppers thinly.
  3. Heat oven to 50 degrees Celsius / 125 degrees Fahrenheit
  4. Place sliced peppers on an oven-safe rack.
  5. Place peppers in the oven and leave the oven door slightly ajar

Drying the peppers can take 2-5 hours, depending on how thick you sliced the peppers. To be on the safe side, check on peppers after 1 hour.

Freeze whole peppers

  1. Clean and dry your peppers
  2. Remove green stems and place peppers in freezer bags.
  3. Remove as much air from the bag as possible and place in the freezer until needed

Can you keep jalapeno plants indoors?

We have been growing jalapeno peppers indoors for many years with excellent results.

Providing sufficient light and controlling the temperature are the two main challenges you will face when growing jalapeno peppers indoors.

When starting the plants, we use grow lights and heat mats to control soil temperatures.

As the plant develops, we move them outdoors to greenhouses and a conservatory with plenty of natural light.

The challenge is, however, to control the temperature when the weather is scorching.

For us, it has been vital to invest in a solution with window panes that allow for excellent airflow and circulation without stressing the plants.

Are jalapenos hot peppers?

JalapeƱo peppers are not hot peppers like the Bhut Jolokia ghost peppers but have more attitude than the typical sweet bell pepper.

Scoville Heat Units (SHU) are a popular method to indicate the heat of any given pepper variety.

For reference, the Bell pepper is given a value of 0-100 SHU, whereas Cayenne peppers range between 25 000 – 50 000 SHU. On the extreme side, the Bhut Jolokia ghost pepper is given a range of 750 000 – 1 500 000 SHU.

On the other hand, Jalapenos are given 2500 – 10 000 SHU. And for me, that is hot enough and ideal for many dishes and uses.

Are jalapeno pepper plants perennials?

Pepper plants are perennials in their native environment. But for most home gardeners, peppers are grown as annuals.

You can, however, overwinter your pepper plants indoors following the steps below:

  1. Trim all leaves from the plant leaving only the main stem and 2-4 branches
  2. Remove and clean root ball.
  3. Trim roots and dunk root ball in neem oil, organic soap, and water solution
  4. Plant in a pot with fresh soil and place in a cool spot with some indirect light
  5. Trim any new leaves and water sparingly

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants and garden vegetables. For the past two years he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.