Nasturtium in Zone 6B — Texas

Nasturtiums are a fantastic addition to any Texas garden. The peppery flavor of the leaves and flowers adds a unique zest to salads, while the seed pods can be pickled for a caper-like treat. Plus, their vibrant colors bring a cheerful touch to your garden beds and containers.

Even with our unpredictable weather, growing nasturtiums is manageable. Our long growing season, roughly 230 days, gives you plenty of time to enjoy these beauties. With careful planning, you can work around the challenges of the Texas heat and enjoy a bountiful harvest.

Starting nasturtiums indoors is possible, but direct sowing is generally preferred since they don't love being transplanted. However, if you're eager to get a head start, especially for an early spring bloom, you can start seeds indoors from late February through mid March. This gives you about 4 weeks before you'd want to put them outside.

Use seed trays with a good seed-starting mix and provide warmth and light. Bottom watering is a great way to keep the soil consistently moist without overwatering – just set the tray in a shallow dish of water and let the soil absorb it. Keep in mind that our early spring can bring unexpected temperature swings, so indoor starts require a little extra attention.

Transplanting nasturtiums outdoors should happen from early to late April, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sun and wind.

Space the plants 10-12 inches apart to allow for their trailing growth habit. Keep an eye on the weather forecast around transplant time; a late freeze can still happen. If a cold snap is predicted, be prepared to cover your young plants.

Direct sowing is the recommended method for nasturtiums in Texas, as they can be sensitive to transplanting. You can direct sow from early April through early September, giving you a wide window to work with. This allows for succession sowing and continuous blooms.

Prepare your soil by loosening it and ensuring it's well-draining. Nasturtiums aren't picky about soil, and actually prefer it a bit poor. Sow seeds 10-12 inches apart and about half an inch deep. Keep the soil consistently moist until germination, which usually takes about a week or two, depending on soil temperature.

Nasturtiums are relatively drought-tolerant and thrive in drier conditions, making them a great choice for Texas gardens. Be careful not to overwater them, especially in our variable humidity. Less is definitely more when it comes to watering these plants.

During the spring and fall, when temperatures are milder, water deeply but infrequently. Aim for about 1 inch of water per week, only when the top 2 inches of soil feel dry to the touch – use the finger test! In the heat of summer, you might need to water more often, but still let the soil dry out slightly between waterings.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases, especially with our variable humidity. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A light layer of mulch around the base of the plants can help retain moisture and suppress weeds, but don't overdo it in our humid climate.

You can expect your first harvest of nasturtium flowers and leaves about 55 days after planting, which means late May through early November if you're sowing from spring through early September. The flowers are ready to harvest when they are fully open and brightly colored. The leaves can be harvested at any time.

To harvest, simply snip off the flowers or leaves with scissors or your fingers. Be gentle to avoid damaging the plant. Regular harvesting encourages continued production of both flowers and leaves. As the first frost approaches in early November, harvest any remaining flowers and seed pods. The seed pods can be pickled for a unique treat, even green ones that haven't fully matured.

Here are a few common issues 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 lush growth, which can be exacerbated by over-fertilizing, especially with nitrogen.
• How to fix/prevent it: Nasturtiums can act as a trap crop, drawing aphids away from other plants. Check your plants regularly and blast aphids off with a strong stream of water from the hose.

Cabbage Caterpillars

• What it looks like: Green caterpillars munching on leaves, leaving behind holes and droppings.
• What causes it: Cabbage white butterflies lay their eggs on the leaves, which hatch into hungry caterpillars.
• How to fix/prevent it: Handpick caterpillars off the plants.

Black Fly

• What it looks like: Tiny black flies, often seen swarming around the plant.
• What causes it: Warm, humid conditions and overwatering.
• How to fix/prevent it: Ensure good air circulation around the plants and avoid overwatering.

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 some afternoon shade during the hottest part of the day can help. Also, watch out for flash floods which can quickly drown plants in poorly draining soil.

Nasturtiums are great companions for many plants in your Texas garden. They do well planted near tomatoes, cucumbers, and squash. Nasturtiums attract beneficial insects that can help pollinate these crops. They also deter pests like squash bugs and cucumber beetles.

Nasturtiums are also beneficial near broccoli and cabbage, as they can help repel cabbage moths and their hungry caterpillars. Avoid planting nasturtiums near fennel, as they can inhibit each other's growth. Keep in mind that companion planting is just one tool in your gardening arsenal, and it's not a guaranteed solution to all problems.