Nasturtium in Zone 9B — Gulf Coast

Nasturtiums are a fantastic addition to any Gulf Coast garden. Their peppery leaves and vibrant flowers add a unique flavor to salads and a pop of color to your plate. Plus, they're incredibly versatile – you can even pickle the seed pods! Growing these beauties is surprisingly easy and rewarding.

Our long growing season here on the Gulf Coast – nearly 320 days! – means you've got plenty of time to get Nasturtiums established. Sure, we deal with high humidity and the occasional hurricane scare, but with a little planning, you can enjoy these edible flowers practically year-round.

Starting Nasturtiums indoors isn't essential in our climate, but it can give you a jump start. If you want to get a head start on blooms, sow seeds indoors in early to late January, about four weeks before you plan to transplant. Use seed trays with good drainage and keep them in a warm spot with plenty of light.

Bottom watering is your friend when starting seeds indoors; it helps prevent damping off, which can be a problem with our high humidity. Since spring comes early to the Gulf Coast, be ready to move your seedlings outdoors as soon as the weather allows.

Transplant your Nasturtium seedlings outdoors from early February through early March. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunshine and humidity.

Space the plants 10-12 inches apart in well-draining soil. Keep an eye on the weather forecast – late cold snaps can happen, even here. If a freeze threatens, cover your seedlings to protect them.

Direct sowing is the preferred method for Nasturtiums, as they don't always love being transplanted. Wait until after the last expected frost, typically early February, and you can continue direct sowing through early October. Choose a spot with full sun to part shade.

Prepare the soil by loosening it and removing any weeds. Nasturtiums actually thrive in slightly poor soil, so don't worry about adding too much fertilizer. Sow the seeds about ½ inch deep and 10-12 inches apart. Keep the soil consistently moist until the seedlings emerge, usually within a week or two.

Nasturtiums are pretty drought-tolerant, which is a bonus during our hotter months here on the Gulf Coast. However, consistent watering, especially when they're young, is key to getting them established. Once established, less is definitely more.

During the spring and fall, when rainfall is more frequent, you might only need to water them once a week, if that. Stick your finger about two inches deep into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week. In the heat of summer, you might need to water more often, but be careful not to overdo it with our high humidity. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases.

Yellowing leaves can be a sign of overwatering, while wilting leaves indicate underwatering. A light layer of mulch can help retain moisture in the soil and suppress weeds, but avoid piling it up against the stems, which can lead to rot in our humid climate.

You can expect your first Nasturtium harvest in early April if you planted early, and the harvest can continue all the way through mid-December! Both the flowers and leaves are edible. The flowers are at their peak flavor when fully open, so that's the time to snip them off.

When harvesting, use scissors or garden shears to avoid damaging the plant. Regular harvesting encourages more flower production. As the season winds down in late fall, consider harvesting the seed pods for pickling. They make a great substitute for capers.

Here are some common problems you might encounter growing Nasturtiums in the Gulf Coast:

Aphids

• What it looks like: Clusters of tiny, soft-bodied insects on stems and leaves, often accompanied by sticky honeydew.
• What causes it: Aphids are attracted to stressed plants, and our humid conditions can sometimes weaken plants.
• How to fix/prevent it: Nasturtiums are often used as a trap crop for aphids, meaning they attract aphids away from your other plants. You can also blast them off with a strong stream of water from the hose or introduce beneficial insects like ladybugs.

Cabbage Caterpillars

• What it looks like: Holes in the leaves, often with green or brown caterpillars present.
• What causes it: Cabbage white butterflies lay their eggs on Nasturtiums, and the caterpillars hatch and start munching.
• How to fix/prevent it: Handpick the caterpillars off the plants or use a natural insecticide like Bacillus thuringiensis (Bt). Covering your plants with row covers can also prevent the butterflies from laying eggs.

Black Fly

• What it looks like: Small, black, fly-like insects clustered on new growth, causing distorted leaves and stunted growth.
• What causes it: Black fly thrive in warm, humid conditions and can quickly infest plants.
• How to fix/prevent it: Spray plants with insecticidal soap or neem oil, focusing on the undersides of leaves. Ensure good air circulation around the plants to deter black fly infestations.

Gulf Coast Specific Challenges: Our hot heat, very-high humidity, and wet-year-round rainfall can create a perfect environment for fungal diseases and pest infestations. Good air circulation and proper watering practices are essential for keeping your Nasturtiums healthy.

Nasturtiums make great companions for several plants in the Gulf Coast garden. Plant them near tomatoes, cucumbers, and squash to deter pests like squash bugs and aphids. They also work well with broccoli and cabbage, helping to repel cabbage moths.

Avoid planting Nasturtiums near fennel, as they can inhibit each other's growth. Otherwise, they're pretty easygoing and can be a beneficial addition to your garden ecosystem.