Jalapeño Peppers in Zone 7B — Desert Southwest

Jalapeño peppers thrive here, and the satisfaction of harvesting your own spicy peppers after nursing them through the spring is hard to beat. Plus, they're incredibly versatile in Southwest cuisine, from salsas to stuffing to grilling. You'll be adding homegrown flavor to your meals in no time.

Our extreme heat and alkaline soil can be tough on plants, but with careful timing around our two growing seasons, you can absolutely grow fantastic jalapeños. We have a long growing season of around 245 days, so there's plenty of time to get a great harvest.

Starting jalapeño peppers indoors is the way to go in the Desert Southwest. You'll want to get your seeds going late January through mid February. This gives them plenty of time to get a head start before our transplant window opens up.

Use seed trays with a good seed-starting mix. Keep them warm, around 75-80°F, and provide plenty of light. A simple shop light works, or a sunny windowsill if you have one that gets consistent light. Don't forget to water from the bottom to encourage strong root growth and avoid damping off.

Remember, spring comes early here. Starting indoors gives you a jump on the season and helps your peppers establish before the real heat hits.

Transplant your jalapeño seedlings outdoors late March through late April, once the risk of frost has passed. Before planting them directly in the ground, you'll want to harden them off. This means gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade each day, increasing the time and sun exposure gradually.

Plant them 14-18 inches apart in well-draining soil. Keep an eye on the weather forecast around transplant time. We can still get some unexpected cold snaps, so be ready to cover your seedlings if necessary.

Consistent watering is key for jalapeños, especially in our arid climate. While they aren’t drought-tolerant, a little water stress can actually increase their heat level, so it's a bit of a balancing act.

During the spring, when temperatures are milder, water deeply once or twice a week, giving them about 1-2 inches of water each time. As the extreme heat of summer arrives, increase watering to every other day, or even daily, providing 2-3 inches of water per week. Once the monsoon moisture kicks in (hopefully!), you can often reduce watering frequency. Use the finger test: if the top 2 inches of soil are dry, it's time to water.

Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases in our humid monsoon season. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, like straw or wood chips, helps retain moisture and regulate soil temperature.

Jalapeño plants can get pretty heavy with peppers, so providing some support is a good idea. While it’s optional, it can prevent branches from breaking and keep your plants from sprawling on the ground.

A single stake works well. Insert the stake near the base of the plant at planting time to avoid damaging the roots later. As the plant grows, gently tie the main stem to the stake with soft twine or plant ties.

Pruning jalapeños is fairly simple. Pinch off any early flowers to encourage the plant to focus on vegetative growth. This will result in a stronger, more productive plant later in the season.

If you prefer smooth peppers, you can remove any fruit that develops corking lines (those stretch marks). These are harmless, but some people prefer the look of smooth peppers. As the first frost approaches around mid- November, you can remove any remaining flowers to redirect the plant's energy into ripening the existing peppers.

You can expect your first harvest of jalapeños mid June through late July, about 75 days after transplanting. You can harvest them green when they're about 3-4 inches long, or wait until they turn red for a sweeter, hotter flavor. Corking lines on the peppers are also a sign of maturity.

To harvest, use scissors or pruning shears to cut the pepper from the plant, leaving a small piece of stem attached. This helps prevent disease. Regular harvesting encourages the plant to produce more peppers. As the first frost approaches in mid- November, harvest all remaining peppers, even the green ones.

Green jalapeños will ripen indoors if you store them in a paper bag with an apple or banana. The ethylene gas emitted by the fruit will speed up the ripening process.

Here are some common problems you might encounter growing jalapeños in the Desert Southwest:

Blossom Drop

• What it looks like: Flowers fall off without setting fruit. Small fruit yellows and drops. The plant looks healthy but produces no fruit.
• What causes it: Temperature stress is the main culprit. Jalapeños don't set fruit well when nights stay above 75°F or days exceed 95°F. Low humidity, excess nitrogen, or poor pollination can also contribute.
• How to fix/prevent it: Be patient – fruit set usually resumes when temperatures moderate. Provide afternoon shade during extreme heat. Keep plants well-watered. Avoid excess nitrogen fertilizer. You can also try hand-pollination.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage natural predators like ladybugs and lacewings. Use insecticidal soap for heavy infestations. Neem oil also works systemically. Avoid excess nitrogen fertilizer, which attracts them.

Pepper Maggots

• What it looks like: Small, white, legless larvae inside the pepper fruit. The peppers may be distorted, prematurely ripen, or drop from the plant.
• What causes it: The pepper maggot fly lays its eggs on the developing peppers. The larvae hatch and tunnel into the fruit.
• How to fix/prevent it: Use sticky traps to catch adult flies. Inspect peppers regularly for signs of infestation and remove any affected fruit. You can also use row covers to prevent the flies from laying eggs on the plants.

Bacterial Leaf Spot

• What it looks like: Small, circular, water-soaked spots on leaves that turn brown or black. The spots may have a yellow halo. Severely affected leaves may drop.
• What causes it: A bacterial infection that thrives in warm, humid conditions. It can spread through splashing water or contaminated tools.
• How to fix/prevent it: Avoid overhead watering. Provide good air circulation around the plants. Remove and destroy any infected leaves. Use copper-based fungicides as a preventative measure.

Desert Southwest Specific Challenges: The extreme heat and low humidity of the Desert Southwest can stress jalapeño plants, making them more susceptible to blossom drop and pests. Our monsoon season, with its high humidity and heavy rainfall, can create conditions favorable for fungal diseases. Monitor your plants closely and take preventative measures to mitigate these challenges.

Good companions for jalapeños include tomatoes, basil, carrots, and onions. Tomatoes provide shade and support. Basil repels pests and improves flavor. Carrots loosen the soil. Onions deter pests and have antifungal properties.

Avoid planting jalapeños near fennel and kohlrabi. Fennel inhibits the growth of many plants. Kohlrabi attracts pests that can also affect jalapeños. By choosing the right companions, you can create a thriving and productive garden, even in the challenging conditions of the Desert Southwest.