Nasturtium in Zone 7B — Texas

Nasturtiums are a fantastic addition to any Texas garden. The peppery flavor of the leaves and flowers adds a unique zest to salads, and they're surprisingly easy to grow. Plus, they attract beneficial insects while adding a splash of color to your veggie patch.

Texas weather can be unpredictable, but Nasturtiums are pretty forgiving if you time things right. Our long growing season, around 255 days, gives you plenty of opportunity to get a crop in, even with the occasional heat wave or late freeze.

Starting Nasturtium indoors isn't usually necessary here in Texas, as they prefer to be direct-sown. But if you're itching to get a head start, you can start seeds indoors from early February through early March, about four weeks before you plan to transplant.

Use seed trays filled with a good seed-starting mix, keep them warm, and provide plenty of light – a sunny windowsill or grow lights will do the trick. Bottom watering is a great way to keep the soil moist without overdoing it. Just set the tray in a shallow dish of water and let the soil soak it up. With our early springs, starting indoors is only really helpful if we're expecting a particularly late cold snap.

If you started your Nasturtiums indoors, aim to transplant them outdoors from mid March through mid April. Before you plant them in their final spot, harden them off by gradually exposing them to outdoor conditions for about a week.

Space them about 10-12 inches apart to give them room to spread. Keep an eye on the weather forecast during this time; a late freeze can still happen, so be ready to cover your seedlings if necessary.

Direct sowing is the preferred method for Nasturtiums in Texas since they don't love having their roots disturbed. You can sow seeds directly into the ground from mid March through mid September.

Choose a spot with full sun to part shade, and make sure the soil is well-draining. Nasturtiums actually thrive in slightly poor soil, so don't worry about amending it too much. Simply press the seeds about half an inch deep, spaced 10-12 inches apart, and keep the soil consistently moist until they germinate.

Nasturtiums are pretty drought-tolerant, which makes them perfect for Texas gardens. Once established, they need very little supplemental watering.

During the spring and fall, when temperatures are milder, you probably only need to water them once a week, if that. In the heat of summer, you might need to water them every few days, especially if we're in a dry spell. Use the finger test: stick your finger about two inches into the soil, and if it feels dry, it's time to water. Give them about an inch of water per week, either from rain or irrigation.

Water at the base of the plant to avoid getting the leaves wet, which can encourage fungal diseases, especially with our variable humidity. Signs of underwatering include wilting leaves and stunted growth. Overwatering, on the other hand, can lead to root rot and yellowing leaves. A light layer of mulch, like shredded bark, can help retain moisture and keep the soil cool during the hottest months.

You can expect your first harvest of Nasturtium flowers and leaves around mid May, and you can continue harvesting all the way through mid November. That's a long harvest window thanks to our mild winters and "two tomato seasons"!

The flowers are ready to harvest when they're fully open, and the leaves can be picked at any time. Gently snip the flowers and leaves with scissors or your fingers, being careful not to damage the plant. Regular harvesting will encourage more blooms and keep your plant producing.

As the first frost approaches in mid- November, harvest any remaining flowers and seed pods. The seed pods can be pickled and used like capers, adding a tangy bite to your winter meals.

Here are a few common problems you might encounter with Nasturtiums in Texas:

Aphids

• What it looks like: Small, pear-shaped insects clustered on stems and leaves, often accompanied by sticky honeydew.
• What causes it: Aphids are attracted to stressed plants. In Texas, this can be due to heat stress or inconsistent watering.
• How to fix/prevent it: Nasturtiums are often used as a trap crop for aphids, meaning they attract aphids away from other plants. You can also blast them off with a strong stream of water from your hose.

Cabbage Caterpillars

• What it looks like: Green caterpillars munching on leaves, leaving behind ragged holes.
• What causes it: These caterpillars are the larvae of cabbage white butterflies, which are common in Texas gardens.
• How to fix/prevent it: Handpick the caterpillars off the plants or use a biological control like Bacillus thuringiensis (Bt).

Black Fly

• What it looks like: Tiny black flies swarming around the plants, especially in the spring.
• What causes it: They're attracted to moist soil and decaying organic matter.
• How to fix/prevent it: Improve air circulation around your plants and avoid overwatering. You can also use yellow sticky traps to catch the flies.

Texas Specific Challenges: The extreme heat, variable humidity, and unpredictable rainfall in Texas can stress Nasturtiums, making them more susceptible to pests and diseases. Consistent watering, good air circulation, and a bit of shade during the hottest part of the day can help keep your plants healthy and productive.

Nasturtiums are great companion plants for several vegetables in your Texas garden. They attract beneficial insects like pollinators and predatory wasps, which can help control pests.

Good companions include tomatoes, cucumbers, and squash, as Nasturtiums help repel common pests that attack these plants. They're also beneficial for broccoli and cabbage, as they can deter cabbage moths. Avoid planting them near fennel, as it can inhibit their growth.