Nasturtium in Zone 7A — Mid-Atlantic

Nasturtiums are a fantastic addition to any Mid-Atlantic garden. Their peppery leaves and vibrant flowers add a unique flavor to salads and a splash of color to your plate. Plus, they attract pollinators and even act as a trap crop for aphids, making them a valuable ally in the fight against pests during our humid summers.

While we Mid-Atlantic gardeners face challenges like deer pressure, clay soil, and the occasional variable spring weather, nasturtiums are relatively easy to grow if you get the timing right. With our 208-day growing season, you have plenty of opportunity to enjoy these beauties from early summer through late fall.

Starting nasturtiums indoors isn't essential, as they prefer direct sowing. However, if you're eager to get a head start, especially with a late-arriving spring, you can start seeds indoors from early to late March, about four weeks before you plan to transplant.

Use seed trays filled with a well-draining potting mix. Keep them consistently moist – bottom watering works great to avoid damping off. Place the trays in a warm spot with plenty of light, either from a sunny window or a grow light.

Transplant your nasturtium seedlings outdoors from mid April through early May, once the danger of frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week.

Choose a sunny spot with well-drained soil, spacing the plants 10-12 inches apart. Keep an eye on the weather forecast; those unexpected late frosts we sometimes get in April can still nip young plants.

Direct sowing is the preferred method for nasturtiums, as they don't love having their roots disturbed. You can direct sow from mid April through late August, giving you a long window for succession planting and continuous blooms.

Prepare your soil by loosening it and removing any large stones. Nasturtiums aren't picky about soil, thriving even in poor conditions. Sow seeds 1/2 inch deep, spacing them 10-12 inches apart. Keep the soil consistently moist until seedlings emerge.

Nasturtiums are quite drought-tolerant once established, which is a good thing given our Mid-Atlantic humidity. Overwatering can actually lead to more foliage and fewer flowers, so less is definitely more.

During the spring and fall, when temperatures are milder and rainfall is more consistent, you probably won't need to water nasturtiums at all unless we're experiencing a dry spell. During the heat of our humid summers, check the soil moisture with the finger test – if the top two inches are dry, it's time to water. Aim for about an inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Wilting leaves are a sign of underwatering, while yellowing leaves can indicate overwatering. A light layer of mulch around the base of the plants can help retain moisture and suppress weeds, but don't overdo it, as too much mulch can keep the soil too wet.

You can expect your first harvest of nasturtium flowers and leaves from early June through late October, about 55 days after planting. Both the flowers and leaves are edible, offering a peppery bite to salads and other dishes.

Harvest flowers when they are fully open, ideally in the morning after the dew has dried. Gently snip the stems just above a leaf node to encourage more blooms. The leaves can be harvested at any time. For a caper-like treat, harvest the seed pods while they are still green and firm.

As the first frost approaches in late October, harvest any remaining flowers and leaves. The seed pods can be left to dry on the plant, and you can collect them for next year's planting.

Nasturtiums are generally easy to grow, but here are a few common problems to watch out for in the Mid-Atlantic:

Aphids

• What it looks like: Clusters of small, soft-bodied insects on stems and undersides of leaves, often accompanied by sticky honeydew.
• What causes it: Aphids are attracted to stressed plants and can thrive in warm, humid conditions.
• How to fix/prevent it: Nasturtiums are often used as a trap crop to attract aphids away from other plants. You can blast aphids off with a strong stream of water, introduce beneficial insects like ladybugs, or use insecticidal soap if the infestation is severe.

Cabbage Caterpillars

• What it looks like: Holes in leaves, often with green droppings nearby. You might also see small green caterpillars.
• What causes it: Cabbage white butterflies lay their eggs on nasturtiums, and the caterpillars hatch and feed on the leaves.
• How to fix/prevent it: Handpick caterpillars off the plants, cover plants with netting to prevent butterflies from laying eggs, or use Bacillus thuringiensis (Bt), a biological insecticide.

Black Fly

• What it looks like: Similar to aphids, these small black flies cluster on new growth, sucking sap and weakening the plant.
• What causes it: They thrive in warm, humid conditions and are attracted to stressed plants.
• How to fix/prevent it: Blast them off with water, use yellow sticky traps, or apply insecticidal soap. Ensure good air circulation around your plants.

Mid-Atlantic Specific Challenges: The moderate-to-hot heat and humid humidity of our summers can create ideal conditions for pests and fungal diseases. Regular monitoring, good air circulation, and avoiding overwatering are key to keeping your nasturtiums healthy.

Nasturtiums make excellent companions for many garden plants in the Mid-Atlantic. They are particularly beneficial when planted near:

• Tomato: Nasturtiums can help repel tomato hornworms and other pests.
• Cucumber and Squash: They attract pollinators, increasing fruit production.
• Broccoli and Cabbage: As a trap crop, they lure cabbage white butterflies away from these brassicas.

Avoid planting nasturtiums near:

• Avoid planting near herbs like rosemary and sage, which prefer drier conditions, as nasturtiums might increase the humidity around them.