Nasturtium in Zone 8A — Florida

Nasturtiums are a fantastic addition to any Florida garden. The peppery flavor of the leaves and flowers adds a unique zing to salads, and they're beautiful trailing from containers or spilling over garden beds. Plus, they attract beneficial insects while acting as a trap crop for pests that might otherwise bother your prized veggies.

While Florida gardening has its challenges – humidity, nematodes, and the occasional hurricane, to name a few – Nasturtiums are relatively low-maintenance and thrive in our long growing season, which stretches roughly from early March through early December. With a little attention to timing, you can enjoy these beauties for most of the year.

Starting Nasturtiums indoors isn't usually necessary here in Florida, but it can give you a head start if you're itching to get things going before the last expected frost. If you choose to start indoors, begin in late January through mid February, about four weeks before you plan to transplant.

Use seed trays filled with a well-draining seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water and let the soil absorb it from the bottom. This helps prevent damping-off disease, which can be a problem in our humid climate. Provide warmth and bright light, and your seedlings should be ready to transplant in a few weeks. Remember, our spring can be a bit reversed, so don't jump the gun too early!

Transplanting Nasturtiums outdoors should happen in early March through early April, after the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade and increase the time and sunlight each day.

When transplanting, space the plants about 10-12 inches apart. Be gentle, as Nasturtiums don't love having their roots disturbed. Keep an eye on the weather forecast – a late cold snap can still happen, even in Florida.

Direct sowing is the preferred method for Nasturtiums, as they resent transplanting. The best time to direct sow is early March through late September, after any danger of frost has passed. Soil temperatures need to be at least 65°F for optimal germination.

Choose a spot with well-drained soil and full sun to part shade. Lightly till the soil and remove any weeds or debris. Sow 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. Don't overwater, though – Nasturtiums prefer slightly drier conditions.

Nasturtiums are drought-tolerant and thrive in slightly poor, dry soil, which makes them well-suited to Florida's sandy soil conditions. In fact, too much water or fertilizer can lead to excessive foliage growth at the expense of flowers. Less is definitely more when it comes to watering these plants.

During the cooler months (fall, winter, and early spring), you'll likely only need to water your Nasturtiums if we're experiencing a prolonged dry spell. Use the finger test – stick your finger about two inches into the soil. If it feels dry, it's time to water. Aim for about ½ inch of water per week, focusing on the base of the plant to avoid wetting the foliage.

During our hot and humid summers, you might need to water more frequently, especially if your Nasturtiums are in containers. Check the soil moisture regularly and water when the top inch or two feels dry. Again, water at the base of the plant to minimize fungal diseases, which are common in Florida's humid climate. Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering can lead to yellowing leaves and root rot. A light layer of pine straw mulch around the base of the plants can help retain moisture and suppress weeds.

You can expect your first Nasturtium harvest in late April through early December, about 55 days after planting. Both the flowers and leaves are edible and have a peppery flavor. Harvest flowers when they are fully open and brightly colored. Snip the leaves as needed, taking care not to remove too many at once, which can stress the plant.

The seed pods are also edible and can be pickled like capers when they are still green and tender. To encourage continued production, deadhead spent flowers regularly. As the first frost approaches in early December, you can collect the remaining seeds to save for planting next year. You can also let the plants self-seed, but be aware that they may not come true to type.

Here are some common problems you might encounter with Nasturtiums in Florida:

Aphids

• What it looks like: Clusters of tiny green, black, or brown insects on stems and leaves. Leaves may be curled, distorted, or sticky.
• What causes it: Aphids are attracted to stressed plants, and warm, humid conditions can encourage their populations to explode.
• How to fix/prevent it: Nasturtiums are often used as a trap crop for aphids, meaning they attract aphids away from other more valuable plants. You can also blast aphids off with a strong stream of water from the hose. Insecticidal soap or neem oil can be used for heavy infestations.

Cabbage Caterpillars

• What it looks like: Holes in leaves, often with green or brownish droppings nearby. You might also spot the caterpillars themselves, which are green and blend in well with the foliage.
• What causes it: Cabbage white butterflies lay their eggs on Nasturtium leaves, and the caterpillars hatch and start feeding.
• How to fix/prevent it: Handpick caterpillars off the plants. Bacillus thuringiensis (Bt) is an effective organic control method.

Black Fly

• What it looks like: Similar to aphids, but black in color. They suck sap from the plant, weakening it.
• What causes it: Warm, humid conditions favor black fly infestations.
• How to fix/prevent it: Blast them off with water. Insecticidal soap or neem oil can also be used.

Florida Specific Challenges: Florida's hot, humid summers and wet-summer rainfall can create ideal conditions for fungal diseases. Ensure good air circulation around your Nasturtiums by spacing them properly and pruning away any overcrowded foliage. Avoid overhead watering, especially in the evenings, and consider using a copper fungicide preventatively. Also, be aware that nematodes can be a problem in Florida soils. While Nasturtiums aren't particularly susceptible, it's always a good idea to amend your soil with organic matter to improve its health and suppress nematode populations.

Nasturtiums are excellent companion plants for many vegetables in the Florida garden. They attract beneficial insects like pollinators and predatory wasps, while also acting as a trap crop for pests.

Good companions include:

• Tomatoes: Nasturtiums deter whiteflies and tomato hornworms.
• Cucumbers: They help repel cucumber beetles.
• Squash: Nasturtiums can attract squash vine borers away from your squash plants.
• Broccoli and Cabbage: They help deter cabbage moths and other pests that attack brassicas.

Avoid planting Nasturtiums near fennel, as they can inhibit each other's growth. Otherwise, these versatile plants get along well with most garden vegetables.