Nasturtium in Zone 5B — Northeast

Nasturtiums are a fantastic addition to any Northeast garden. The peppery flavor of the leaves and flowers adds a unique zest to salads and other dishes, while the vibrant colors brighten up your garden beds. Plus, they're relatively easy to grow, even with our rocky New England soil.

Our short growing season here in Zone 5B presents some challenges, but nasturtiums mature quickly, making them a manageable and rewarding crop. With a little planning and attention to timing within our 168-day growing season, you can enjoy a bountiful harvest.

Starting nasturtiums indoors isn't strictly necessary, as they prefer direct sowing, but it can give you a head start if you're eager to see those first blooms. If you choose to start indoors, aim for late March through mid April, about four weeks before you plan to transplant them outside.

Use seed trays filled with a good seed-starting mix and keep them in a warm, well-lit area. Bottom watering is a great way to keep the soil consistently moist without overwatering, which can be a problem. Remember, our springs in the Northeast can be unpredictable, so keep an eye on the weather before transplanting.

Transplanting nasturtiums outdoors should happen in early to late May, once the danger of frost has passed. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space the plants 10-12 inches apart to give them room to spread. Keep in mind that we can still get some chilly nights even in May, so be prepared to cover the plants if a late frost is predicted.

Direct sowing is the preferred method for nasturtiums, as they don't always love being transplanted. Wait until early May through early August, after any risk of frost is gone, to sow your seeds directly into the garden.

Choose a spot with full sun to part shade and prepare the soil by loosening it and removing any large rocks (a common task for us Northeast gardeners!). Sow seeds 10-12 inches apart and about half an inch deep. Nasturtiums actually thrive in slightly poor soil, so don't worry about adding too much fertilizer.

Nasturtiums are quite drought-tolerant and prefer drier conditions, which is good news for us in the Northeast where we get a decent amount of rain. Overwatering can lead to more foliage than flowers, so less is definitely more with these plants.

During the growing season, check the soil moisture by using the finger test – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Aim for about an inch of water per week, especially during dry spells. Water at the base of the plants to avoid getting the leaves too wet, which can be a problem in our moderate-to-humid climate.

Keep an eye out for signs of overwatering, such as yellowing leaves, or underwatering, such as wilting. A light layer of mulch can help retain moisture in the soil without making it too wet, which is helpful with our even rainfall.

You can expect your first harvest of nasturtium flowers and leaves in late June through early October, about 55 days after planting. The flowers are ready to harvest when they are fully open and brightly colored.

To harvest, simply snip the flowers or leaves off the plant with scissors or your fingers, being careful not to damage the surrounding foliage. Regular harvesting encourages the plant to produce more flowers and leaves, extending your harvest throughout the season.

As our first frost approaches in early October, you can harvest any remaining flowers and leaves to use in salads or other dishes. You can also collect the seed pods and pickle them for a caper-like treat.

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

Aphids

• What it looks like: Clusters of tiny green, black, or white bugs on stems and leaves. Leaves may be sticky or distorted.
• What causes it: Aphids are attracted to stressed plants, but nasturtiums can be used as an intentional trap crop, drawing them away from other vegetables.
• How to fix/prevent it: Regularly inspect plants. If aphids appear, blast them off with a strong stream of water from your hose. Since they are a trap crop, you can let them be to protect your other plants.

Cabbage Caterpillars

• What it looks like: Holes in leaves, often with green or brown droppings nearby. You might see small green caterpillars on the plant.
• What causes it: Cabbage white butterflies lay their eggs on the leaves, which hatch into hungry caterpillars.
• How to fix/prevent it: Handpick caterpillars off the plants. Covering plants with netting can prevent butterflies from laying eggs.

Black Fly

• What it looks like: Similar to aphids, tiny black flies will congregate on the plant and suck its juices.
• What causes it: These pests thrive in warm, humid conditions.
• How to fix/prevent it: Similar to aphids, spray them off with water, and apply insecticidal soap to the affected areas.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create ideal conditions for pests like aphids and cabbage caterpillars. Regular monitoring and prompt action are key to keeping your nasturtiums healthy and productive.

Nasturtiums make excellent companions for several plants in the Northeast garden. They attract pollinators and can deter certain pests.

Tomatoes, cucumbers, and squash benefit from having nasturtiums nearby as they help repel squash bugs and other unwanted insects. Broccoli and cabbage also appreciate nasturtiums as companions because they help deter cabbage moths and other pests that can damage these crops. Avoid planting nasturtiums near fennel, as they can inhibit each other's growth.