Nasturtium in Zone 9B — Texas

Nasturtiums are a fantastic addition to any Texas garden. Not only are their peppery leaves and vibrant flowers delicious in salads and other dishes, but they attract beneficial insects and thrive in our long growing season. Plus, they’re super easy to grow, giving you a big reward for minimal effort.

Sure, we deal with our share of challenges here in Texas, from the brutal Texas heat to unpredictable weather. But with a 308-day growing season, we have plenty of time to get these beauties established and enjoy their bounty. Careful timing is key, and you'll be enjoying these from spring to fall.

While nasturtiums do best when direct sown, you *can* start them indoors if you're itching to get a jump start, especially if we're having an unusually cool start to the year. Begin in early to late January, about four weeks before you'd like to transplant them outside. This gives them a head start before the heat kicks in.

Use seed trays or small pots filled with well-draining potting mix. Keep them warm and provide plenty of light – a sunny windowsill or grow lights work well. Remember to water from the bottom to encourage strong root growth and prevent damping off, a common problem with seedlings. Given our early spring character here in Texas, starting indoors can give you an edge.

Once the danger of frost has passed – typically mid February through mid March – and your seedlings have a few sets of true leaves, it's time to transplant them outdoors. Before you do, be sure to harden them off. Gradually expose them to outdoor conditions for about a week. This helps them adjust to the Texas sun and wind.

Plant them 10-12 inches apart in a sunny spot with well-drained soil. Keep an eye on the weather forecast and be prepared to cover them if we get one of those late, unpredictable freezes.

Direct sowing is the preferred method for nasturtiums, as they don't always love being transplanted. Wait until mid February through early October, after the last frost, to sow your seeds directly into the garden. This wide window allows for succession planting and a continuous harvest.

Prepare the soil by loosening it and removing any weeds. Nasturtiums aren't picky about soil, but good drainage is important. Sow the seeds about ½ inch deep and 10-12 inches apart. Keep the soil consistently moist until the seedlings emerge, which usually takes about a week or two, depending on soil temperature.

Nasturtiums are relatively drought-tolerant and actually prefer slightly dry conditions, making them a great choice for Texas gardens. Overwatering can lead to more foliage than flowers, which isn't what we want.

During the spring and fall, when temperatures are milder and rainfall is more likely, water only when the top two inches of soil feel dry to the touch. Stick your finger in there to check! In the brutal Texas heat of summer, you may need to water more frequently, but still be careful not to overdo it. Aim for about an inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid getting the leaves wet, especially with our variable humidity, which can encourage fungal diseases.

If the leaves start to wilt and turn yellow, you're likely overwatering. If they look droopy and dry, you're underwatering. A layer of mulch around the base of the plants can help retain moisture in our unpredictable conditions and suppress weeds, too.

You can expect your first harvest of nasturtium flowers and leaves from early April through early December, about 55 days after planting. That long growing season is one of the perks of gardening in Texas!

Harvest the flowers when they are fully open for the best flavor and visual appeal. Simply snip them off the stem. For the leaves, harvest young, tender ones for a milder flavor. The seed pods can be harvested when they are still green and plump. Regular harvesting encourages the plant to produce more flowers and leaves.

As the first frost approaches in early December, harvest any remaining flowers and seed pods. The leaves may start to decline, but you can still use them until they are no longer palatable.

Even though they’re easy to grow, nasturtiums can sometimes face a few problems in the Texas garden. Here are some common issues and how to deal with them:

Aphids *What it looks like:* Tiny green, black, or white insects clustered on stems and leaves, causing distorted growth. *What causes it:* Aphids are attracted to stressed plants, and our unpredictable weather can sometimes cause stress. *How to fix/prevent it:* Nasturtiums are often used as a trap crop for aphids, drawing them away from other plants. You can also blast them off with a strong stream of water from the hose.

Cabbage Caterpillars *What it looks like:* Green caterpillars munching on leaves, leaving holes and ragged edges. *What causes it:* Cabbage white butterflies lay their eggs on the leaves, and the caterpillars hatch and start feeding. *How to fix/prevent it:* Handpick the caterpillars off the plants or use an organic insecticide like Bacillus thuringiensis (Bt).

Black Fly *What it looks like:* Small black flies that can infest the plant in large numbers, sucking sap and weakening it. *What causes it:* Black flies are attracted to moist conditions and can thrive during periods of high humidity. *How to fix/prevent it:* Improve air circulation around the plants by spacing them properly. You can also use yellow sticky traps to catch the flies.

Texas Specific Challenges: The hot-to-extreme heat and variable humidity of Texas can stress nasturtiums, making them more susceptible to pests and diseases. Providing adequate shade during the hottest part of the day and ensuring good air circulation can help mitigate these problems.

Nasturtiums are great companions for many plants in the Texas garden. They attract beneficial insects and can even repel some pests.

Good companions include tomatoes, cucumbers, and squash. Nasturtiums help repel pests like aphids and squash bugs, protecting these vulnerable crops. They also work well with broccoli and cabbage, deterring cabbage moths.

Avoid planting nasturtiums near fennel, as it can inhibit their growth. Otherwise, nasturtiums are pretty easygoing and get along with most other plants.