How to Grow Jalapeños

A far wider range of jalapeño peppers is available as seeds than as produce in the shops. There are lots of varieties to grow with different heat levels, colours, and unique flavours!

How to Sow Jalapeños

Jalapeño peppers are not hard to grow from seed but need a long time to mature. It is therefore best to start sowing them early indoors or in your S-Series Smart Mini Greenhouse. Late winter to early spring is generally a good time. Jalapeño plants can be grown to maturity in your automated garden or moved to a sunny, sheltered, and warm position outside when the night temperatures are a minimum of 10-15°C.

Fill a pot, tray, or multi-cell tray with peat-free compost and water it. Sow the seeds at least 2cm apart and cover lightly with compost or vermiculite unless the seed packet specifies that they need light to germinate. Water again carefully. Putting a plastic dome or cling film on top can help germination, but make sure it has air holes for ventilation. Keep the soil evenly moist until the seeds germinate because if they dry out, they may not germinate at all. Having said that, be careful not to overwater!

Jalapeño seeds ideally need 20-30°C to germinate well and normally appear within 7-14 days. Some varieties can take longer to germinate. Once the seedlings appear, remove the plastic and place them in a bright location with 12-16 hours of light. 20°C is an ideal growing temperature.

How to Take Care of Jalapeños

Transplant the seedlings to their individual 7-9cm pots when at least one set of true leaves has formed. Repot them into slightly larger pots when the roots start to stick out at the bottom, aiming for a 30cm pot as the final one.

Jalapeño plants generally don’t need pinching out, as their natural growth habit encourages branching. However, you can prune lightly to shape the plant or remove any overly leggy growth.

You can keep the pot in your S or H if you have space or put it outside in early summer when the night temperatures are at least above 10°C. To acclimatise the plants to outdoor conditions, lift them outside in a sheltered, lightly shaded spot during the day, and put them back in at night. Gradually increase the time outside. Do this for about two weeks before leaving them out all the time.

Try to keep the pots evenly watered and feed every 10-14 days with a balanced liquid fertiliser, switching to a high-potash feed every 7-10 days once the first fruits start to set.

It’s a good idea to stake the plants to provide additional support, as jalapeño plants can grow heavy with fruit.

When growing in your S, pollinators may struggle to get to your plants, so they will need help to pollinate properly. Stroke the inside of the flowers with a small paintbrush to pass pollen from one flower to another.

Mist the foliage regularly when growing indoors or under cover with tepid water to discourage red spider mites and to help flower set.

How to Harvest Jalapeños

Jalapeños can be harvested when they are green or red, depending on your preferred flavour and heat level. Green jalapeños have a fresher, crisper taste, while red ones are sweeter and slightly hotter. Use a sharp pair of scissors or pruning shears to cut the peppers from the plant, leaving a small stem attached.

Watch Out!

The biggest problems tend to be red spider mites. Avoid them by regularly misting the plants, especially if grown under cover. Whitefly and aphids can also be a problem, which can be treated with an organic soap spray. Blossom end rot, caused by erratic watering, can occasionally affect jalapeños but is less common than in other peppers.

Pro Tip

Jalapeños thrive in warm and humid conditions. If you’re growing them in your Harvst, ensure good airflow and use a ventilation fan to prevent fungal issues like damping off.

Nerdy Facts

Although jalapeño peppers are treated as an annual plant in our climate, they are actually a perennial. They can be overwintered indoors, but results in the second year can vary.

Recommended Varieties

There are lots of different varieties, but here are some that are suitable to grow in your Harvst and outdoors in a sheltered spot:

‘Jalapeño Early’: A fast-maturing variety ideal for cooler climates.
‘Purple Jalapeño’: Produces striking purple fruit that matures to red.
‘Jaloro’: A unique yellow jalapeño variety with mild heat.
‘F1 Goliath’: A hybrid variety that produces large, thick-walled fruit with consistent heat.
‘NuMex Pinata’: Features multi-coloured fruits that transition from green to yellow, orange, and red.