Nasturtium in Zone 7B — Mid-Atlantic

Nasturtiums are worth growing in any Mid-Atlantic garden for their peppery leaves and vibrant edible flowers that add a zesty kick to salads. They thrive in our moderate-to-hot summers and even attract beneficial insects, making them a fantastic addition to vegetable gardens. Plus, they're easy to grow and bring a splash of color from early summer well into the fall as the nights cool.

While our humid summers and clay soil can present challenges, nasturtiums are surprisingly resilient. With a 214-day growing season, you have ample time to get these beauties established, even with the occasional unexpected late frost we sometimes see in spring. Careful timing and smart watering are your best friends.

Starting nasturtiums indoors is possible, but direct sowing is generally preferred since they resent transplanting. If you want a head start, begin in early to late March, about four weeks before you plan to transplant outdoors. Use seed trays with a well-draining potting mix and provide warmth and bright light.

Bottom watering is key to prevent damping off, which can be a problem in our humid Mid-Atlantic climate. Simply place the seed tray in a shallow dish of water and allow the soil to absorb moisture from the bottom.

Keep in mind that our springs can be variable, so watch the weather forecast and be prepared to hold off transplanting if a cold snap threatens.

Transplant your nasturtium seedlings outdoors from early April through early May, 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 sunlight and temperatures.

Choose a spot with full sun to partial shade, and space the plants 10-12 inches apart. Our Mid-Atlantic weather can be unpredictable this time of year, so keep an eye on the forecast and protect young transplants from any late frosts with row covers or blankets if necessary.

Direct sowing is the easiest and most successful way to grow nasturtiums in the Mid-Atlantic. Sow seeds directly into the garden from early April through late August. This gives you a long window to get a continuous bloom throughout the growing season.

Choose a sunny or partially shaded spot with well-drained soil. Nasturtiums aren't fussy and actually thrive in poorer soil, so don't worry about amending it too much. Sow 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.

After the last frost, soil temperatures should be warm enough for quick germination. A light layer of mulch can help retain moisture and suppress weeds.

Nasturtiums are drought-tolerant and prefer drier conditions, which is good news for Mid-Atlantic gardeners dealing with our humid summers. Overwatering can lead to lush foliage but fewer flowers, so less is definitely more.

During the spring and fall, when temperatures are cooler and rainfall is more frequent, you may only need to water your nasturtiums once a week, if at all. In the heat of summer, especially during dry spells, check the soil moisture regularly. 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 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. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A light layer of mulch, like straw or shredded leaves, can help retain moisture and suppress weeds, but be careful not to over-mulch, as this can also trap moisture.

You can expect your first nasturtium harvest from early June through early November, about 55 days after sowing. Both the flowers and leaves are edible, so harvest them as needed. The flowers are at their peak when fully open, offering the most vibrant color and peppery flavor.

To harvest, simply snip the flowers or leaves with scissors or pinch them off with 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, you can still harvest any remaining flowers and leaves. You can also pickle the green seed pods for a caper-like treat.

Here are a few common problems Mid-Atlantic gardeners might encounter with nasturtiums:

Aphids

• What it looks like: Small, pear-shaped insects clustered on stems and leaves, often accompanied by sticky honeydew and sooty mold.
• What causes it: Aphids thrive in warm, humid conditions, which we often experience in the Mid-Atlantic. They're attracted to lush growth, so over-fertilizing can make the problem worse.
• How to fix/prevent it: Nasturtiums are often used as a trap crop for aphids, drawing them away from other plants. If the infestation is heavy, try blasting them off with a strong stream of water from the hose. You can also introduce beneficial insects like ladybugs, which are natural predators of aphids.

Cabbage Caterpillars

• What it looks like: Green caterpillars chewing holes in leaves. You might also see small white butterflies (cabbage white butterflies) fluttering around your plants.
• What causes it: These caterpillars are the larvae of cabbage white butterflies, which are common in the Mid-Atlantic. They lay their eggs on the underside of leaves, and the caterpillars emerge to feast on your plants.
• How to fix/prevent it: Inspect your plants regularly for eggs and caterpillars. Handpick them off and drop them into a bucket of soapy water. You can also cover your plants with row covers to prevent the butterflies from laying eggs.

Black Fly

• What it looks like: Similar to aphids, black fly are small black insects that cluster on the stems and underside of leaves, sucking plant juices. The damage can cause stunted growth and distorted leaves.
• What causes it: Black fly, like aphids, are attracted to young, tender growth and can proliferate rapidly in warm, humid conditions. Overwatering and poor air circulation can exacerbate the problem.
• How to fix/prevent it: A strong blast of water from a hose can dislodge black fly. Insecticidal soap can also be effective, but be sure to follow the label instructions carefully. Improving air circulation by spacing plants properly can help prevent infestations.

Mid-Atlantic Specific Challenges: Our moderate-to-hot summers and humid conditions can create an ideal environment for pests and diseases. Regular monitoring and proactive measures, such as proper watering and good air circulation, are essential for keeping your nasturtiums healthy and thriving.

Nasturtiums are excellent companion plants in the Mid-Atlantic garden, offering benefits to many common crops. Plant them near tomatoes, cucumbers, and squash to deter pests like squash bugs and aphids. The nasturtiums act as a trap crop, drawing the pests away from your valuable vegetables. Plus, they attract beneficial insects like pollinators and predatory wasps.

They also work well with broccoli and cabbage, helping to repel cabbage moths and other cabbage family pests. Avoid planting nasturtiums near fennel, as they can inhibit each other's growth.