Nasturtium in Zone 6B — Northeast

Nasturtiums are a fantastic addition to any Northeast garden. Their peppery leaves and vibrant flowers bring a unique flavor to salads and a splash of color to your garden beds. Plus, they're incredibly easy to grow, offering a high reward for minimal effort, even in our short growing season.

While our Northeast climate, with its late springs and early frosts, can present challenges, nasturtiums are quick to mature. You can easily squeeze in a full harvest within our 183-day growing season. Careful timing and a little planning will ensure you make the most of summer.

Starting nasturtiums indoors isn't usually necessary, but it can give you a head start, especially if you're itching to get gardening after a long winter. Aim to sow seeds indoors mid-March through early April, about four weeks before the typical transplanting window.

Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light – a sunny windowsill or under grow lights works well. Bottom watering is ideal; set the tray in a shallow dish of water and let the soil absorb it to prevent damping off. Just remember, our late springs often mean keeping those seedlings indoors longer than you might expect.

Transplanting nasturtiums should happen late April through mid May, once the danger of frost has passed. Before moving them outdoors, harden them off for about a week. Gradually expose the seedlings to outdoor conditions, starting with a few hours each day.

When transplanting, space the plants 10-12 inches apart. Keep an eye on the weather forecast – a late frost can still sneak in during this time in the Northeast, so be prepared to cover your seedlings if needed.

Direct sowing is the preferred method for nasturtiums, as they don't always love being transplanted. Wait until late April through early August, after the last expected frost, to sow your seeds directly into the garden.

Choose a spot with full sun to partial shade, and prepare the soil by loosening it and removing any large rocks – typical New England soil prep! Nasturtiums aren't fussy, and they actually thrive in slightly poor soil. Sow seeds 10-12 inches apart and about half an inch deep. Keep the soil consistently moist until the seedlings emerge.

Nasturtiums are wonderfully low-maintenance when it comes to watering, which is great for busy Northeast gardeners. They actually prefer slightly dry conditions and are quite drought-tolerant once established. Overwatering can lead to lush foliage but fewer flowers.

During the spring, when rainfall is generally even in the Northeast, you might not need to water established nasturtiums at all unless we have a particularly dry spell. In the moderate heat and moderate-to-humid conditions of summer, check the soil moisture using the finger test – if the top two inches of soil 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.

Yellowing leaves can indicate overwatering, while wilting leaves suggest underwatering. A light layer of mulch, like straw or wood chips, can help retain moisture in the soil and reduce the need for frequent watering, especially during the warmer months.

You can expect your first harvest of nasturtium flowers and leaves mid June through mid October, about 55 days after planting. The flowers are ready to pick when they are fully open, and the leaves can be harvested at any time. For the seed pods, wait until they are plump and green.

Harvest flowers and leaves in the morning for the best flavor. Pinch off the flowers or snip the leaves with scissors, being careful not to damage the plant. Regular harvesting encourages continued production throughout the season. As the first frost approaches in mid- October, harvest any remaining flowers and seed pods to enjoy before the season ends. You can even pickle the green seed pods for a caper-like treat!

Here are a few common problems you might encounter with nasturtiums in your Northeast garden:

Aphids (intentional trap crop)

• What it looks like: Clusters of small, soft-bodied insects, often green or black, on stems and leaves. Leaves may be sticky or distorted.
• What causes it: Aphids are attracted to nasturtiums, often more so than to other nearby plants. This can be a good thing, as nasturtiums act as a trap crop, drawing aphids away from your prized vegetables.
• How to fix/prevent it: Regularly inspect your nasturtiums for aphids. A strong blast of water from the hose can dislodge them. You can also introduce beneficial insects like ladybugs to control the population. Since they're a trap crop, you might just accept some aphids on your nasturtiums and let them do their job.

Cabbage Caterpillars

• What it looks like: Green caterpillars feeding on leaves, leaving holes and ragged edges. You might also see their droppings (frass) on the plants.
• What causes it: Cabbage white butterflies lay their eggs on brassicas and related plants. The caterpillars hatch and start munching.
• How to fix/prevent it: Handpick caterpillars off the plants. Cover your nasturtiums with netting or row covers to prevent butterflies from laying eggs. Bacillus thuringiensis (Bt) is an effective organic treatment for caterpillars.

Black Fly

• What it looks like: Tiny black flies swarming around the plant, especially in the spring.
• What causes it: The Northeast's sometimes cool, wet springs can create ideal conditions for black flies.
• How to fix/prevent it: Improve air circulation around the plants by spacing them properly. Insecticidal soap can help control infestations.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create favorable conditions for certain pests and diseases. Monitor your nasturtiums regularly, and take action promptly to prevent problems from escalating.

Nasturtiums are excellent companion plants in the Northeast garden. They attract beneficial insects and can even deter some pests.

They are particularly good companions for tomatoes, cucumbers, and squash, as they help repel pests like squash bugs and aphids. Plant them near broccoli and cabbage to deter cabbage white butterflies and their hungry caterpillars. Avoid planting them near fennel, as fennel can inhibit the growth of many plants, including nasturtiums.