When and how to start your seeds

Jalapeños, like many vegetables, should be started inside and allowed to mature into seedlings before being transplanted outside. Starting seeds indoors results in higher germination rates and allows you to select the strongest plants for transplanting, resulting in more abundant, heartier adult plans.

Seeds ideally should be started roughly 5-8 weeks before the final frost. Average frost dates for your area can be found on the Old Farmer’s Almanac, among other sources. We’ve had success starting plants later than this, though results (like so much in gardening) will depend on the geographic area in which you’re located, the weather, and more.

Planting your seeds

We’ve found that the two best options for the “culture” that you initially plant your seeds in are seed-starting soil and coco coir pellets.

A seed-starting soil is a mix of natural components that provide nutrients aimed at encouraging seed germination while avoiding compacting the soil too much, which limits airflow to the roots, and makes germination more difficult. Many mixes of seed-starting soil are available at garden shops and online, and it’s also possible to make your own (an 8:1:1 mixture of rehydrated coco coir:vermiculite:perlite is a good starting point).

Coco coir pellets are dried discs of fiber from the husks of coconuts. These are rehydrated and used as the medium in which to start seeds. These are especially sustainable and widely available online and in garden shops.

We have started seeds using conventional potting soil in the past and still had good results, but prefer the other cultures for their improved germination rates and better suitability when it comes to starting seeds.

Regardless of what option you choose, sow seeds roughly 1/4 inch deep into your culture, lightly filling the hole above the seed with your chosen medium. If you are using seed-starting soil or potting soil, sow seeds 1 inch apart. If you are using coco coir pellets, plant one seed per pellet.

Caring for your newly planted seeds

You’ll want to keep your seeds very warm and moist as they begin to grow: 70–80°F (though 80°+F is even better) and humid but not soggy. Covering your planter with plastic wrap or a clear plastic lid will help lock in heat and moisture (we’ve also left our plants on our radiator when things get cold, but make sure the starting culture doesn’t dry out if you do so). During this period, you’ll want to provide your seeds with a strong light source; if living in a low-light environment, a grow light can be helpful.

Your seeds should germinate, in about 10-21 days, at which point you’ll have very tiny jalapeño plants! You’ll want to continue to care for them until they are ready to be moved into a slightly larger pot, which is known as “potting up.” A good rule of thumb is to wait until plants are 3-4 inches tall or they have developed their 3-4 pairs of “true leaves,” meaning the first leaves to emerge after the initial leaves from germination.

Potting up your seedlings

After your seedlings have reached 3-4 inches in height or have several pairs of true leaves, it is a good idea to transfer them into a larger pot to encourage root growth and further development. Be careful handling them at this point as their stems and root structures are very delicate (coir pellets can be transferred without removing the seedling since the pellets and their cases will break down in the soil). Seedlings should be transferred to 3- or 4-inch containers filled with well-drained potting soil.

In there new pots, plants should be kept roughly 60–70°F and you should continue proving a strong light source for your seedlings. As you allow your plants to grow in their new pots, you can feed them with fertilizer if you choose to do so, but make sure it’s diluted to at least 50% of its usual potency (e.g. if your fertilizer calls for 1 tablespoon of fertilizer per 1 gallon of water, use 1/2 tablespoon or less of fertilizer per gallon at this stage).

Roughly two weeks before you plan on planting your seedlings outside, you’ll need to start a process called “hardening off,” which simply means acclimating them to outside conditions. This will allow the plants to slowly adapt to the harsher outdoor weather (e.g. swings in temperature, heavy rain, etc.) that would otherwise be a shock to their system after their relatively cushy indoor life.

Hardening off your plants

When you harden off your plants, you place them outside for a set period of time before bringing them indoors, and repeat the process daily, extending the amount of time they spend outside each day. You can begin hardening off your plants when overnight temperatures are 45°F but the warmer things are (ideally 55°F) the easier it will be for your plants to acclimate and the faster you can harden them off. 10-14 days is an ideal period of time for the process, though it can be accomplished in 7 or fewer days; however, the less time you take, the greater the risk of shocks that can degrade or even kill the plant.

A strict hardening off calendar isn’t necessary, as long as you generally allow the plants more time outside each day, but we usually follow the below schedule in New York. If your area has more temperate spring conditions, you can accelerate it; if it has harsher conditions, you should take things more slowly. Local university agriculture programs are an excellent resource for gardeners and will often have information and insights about your particular region.

• Day 1: Place outside for one hour during warmest part of the day; indirect sunlight

• Day 2: Place outside for two hours during warmest part of the day; indirect sunlight

• Day 3: Place outside for three hours during the warmest part of the day; indirect sunlight

• Day 4: Place outside for five hours that end at warmest part of the day; direct sunlight

• Day 5: Place outside for seven hours that include the warmest part of the day; direct sunlight

• Day 6: Place outside for nine hours that include the warmest part of the day; direct sunlight

• Day 7: Place outside for 12 hours with the warmest part of the day at the timespan’s midpoint; direct sunlight

• Day 8: Place outside where you plan to plant seedling as soon as you wake up and bring in just before you go to bed

• Day 9: Place outside where you plan to plant seedling as soon as you wake up and bring in just before you go to bed

• Day 10: Place outside where you plan to plant seedling as soon as you wake up and leave all day then overnight

Transplanting seedlings into your containers

Once you’ve hardened off your seedlings, they’re ready to be moved into their final homes in their containers. You should still handle your plants with care since their stems are still fragile.

Jalapeños should be planted in containers that are at least 18 inches deep and 18 inches wide. Dig a hole that is slightly larger than the root ball of the plant and gently break apart the root ball before placing in the soil to encourage root growth. In general, the larger a container you use, the more your plant will thrive as its roots will have more room to grow and more nutrients to access due to the greater volume of soil.

It is recommended to add a tomato cage or stake at the time you transplant instead of later in the season to avoid disturbing roots and to give the plant a frame on which to train itself.

Caring for your plants

Jalapeños, like other vegetables, require lots of sun. Plants should receive a minimum of six hours of direct sunlight a day. We’ve been able to produce fruit with less sunlight, but it’s been fare sparser, and smaller, than under sunnier conditions.

Jalapeños like water, however, dryer growing conditions produce more flavorful—and spicier—fruits. Your containers should have drainage holes or other features that allow excess water to escape. Keeping soil too wet will result in root rot and can kill your plants, not to mention diminishing their flavor. Containers, due to their limited volume, dry out quickly, so check your planters often; at the hottest part of the summer expect to water frequently. If you stick a finger 2-3 inches into the soil and it’s dry, your plants need to be watered.

If fertilizing your plants, apply when they are roughly 6 inches tall to increase yields. Follow manufacturers instructions for all fertilizers but remember that under-fertilizing is better than over-fertilizing. Too much fertilizer also diminishes the flavor and spice of jalapeños. All purpose fertilizers or those that are lower in potassium seem to have the best result. A well-sourced compost applied roughly two weeks after transplanting and again just before fruiting is another good options: add about half an inch over the top of the soil before watering.

Your plants are open-pollinating, meaning that they are pollinated the traditional way that we think of plants being pollinated: bees visiting flowers, wind moving pollen, etc. Sometimes, especially in an urban environment, we’ve had minor issues with pollination; if you'r plants seem to be dropping a lot of flowers (i.e. a flower appears, but no fruit is produced) you might want to consider manually pollinating them. To do so, take a soft-bristled paint brush and gently brush the inside of a flower; then brush the inside of another flower with the brush; continue moving around until all the open flowers on the plant have been brushed. A less labor-intensive way to encourage pollination is to gently shake the plant—this will cause the flowers to express their pollen and hopefully the pollen in the air will pollinate the flowers.

Harvesting and storage

This variety takes roughly 60-80 days to mature, meaning the time from being transplanted into containers until they’re ready to harvest; weather conditions, care, nutrients, and other factors can extend this period. Frequent harvesting encourages more fruit so pick early and often. Jalapeños can be picked at any point of ripeness, however, they will not continue to gain coloration after they’ve been picked (unlike tomatoes, for example). Young, green peppers seem to be hottest; mature, red peppers have a richer flavor. When harvesting, the stem should be snipped with a clean pair of scissors or garden shears—jalapeños shouldn’t be “picked” off the plant. Cleaning the scissors or shears with alcohol or a sanitizing solution is recommended before harvesting; while rare, dirty tools can infect the plant during harvesting. Store peppers at room temperature and never in the fridge; most will last a week without issue, especially if harvested before they ripen and change color. Pickling or drying will greatly extend their usable lifespan.

Fast facts and technical jargon

• Scientific name: Capsicum annuum

• Germination rate: 75%

• Life cycle: Annual

• Days to maturity: ~60 (green)-80 (red) days

• Average size: 2-2.5 in.

• Pollination type: Open pollination

• Eco-consciousness: Organic, non-GMO

• Starting window: Feb.-Apr.

• Days to germination: 10-21

• Adult heigh: 2-3 feet