Nasturtium in Zone 5B — Midwest

Nasturtiums are a fantastic addition to any Midwest garden. Their peppery flavor adds zest to salads, the vibrant flowers brighten up any dish, and they're surprisingly easy to grow here. Plus, they attract beneficial insects while acting as a trap crop for pests that might otherwise bother your prized vegetables.

Our Midwest weather can be unpredictable, with late frosts and summer heat spells, but don't let that scare you off. With a growing season of around 168 days, we have plenty of time to enjoy these beauties. A little planning ensures a bountiful harvest of both flowers and leaves.

Starting Nasturtiums indoors isn't essential in the Midwest, as they actually prefer being direct-sown. However, if you're itching to get a head start, especially with our moderate-to-late springs, you can start them indoors late March through mid April, about four weeks before you'd transplant them outside.

Use seed trays with good drainage and a light potting mix. Keep the soil consistently moist, using bottom watering to avoid damping off. Place the trays in a warm spot with plenty of light – a sunny windowsill or under grow lights works well.

Transplanting Nasturtiums in the Midwest should happen early to late May, once the danger of frost has passed. Before planting them in the ground, harden them off for about a week by gradually exposing them to outdoor conditions. This acclimates them to the sun and wind, preventing transplant shock.

Plant them 10-12 inches apart in well-draining soil. Even though we're past the typical frost dates, keep an eye on the forecast. Those late cold snaps can still happen, so be prepared to cover your seedlings if necessary.

Direct sowing is the preferred method for Nasturtiums, since they don't love having their roots disturbed. In the Midwest, you can direct sow from early May through early August. This gives you a nice long window to get them in the ground.

Choose a spot with full sun to part shade and loosen the soil, but don't worry about amending it too much – Nasturtiums actually thrive in slightly poorer soil. Sow the seeds 10-12 inches apart, about half an inch deep, and keep the soil consistently moist until they germinate. Soil temperatures above 55°F are ideal for germination.

Nasturtiums are pretty low-maintenance when it comes to watering, which is great for us Midwest gardeners who have to deal with our fair share of humidity and wet summers. They're drought-tolerant and actually prefer drier conditions. Too much water can lead to more foliage than flowers, which isn't what we want.

During the typically moderate-to-hot summer months, check the soil moisture by sticking your finger about two inches deep. If it's dry, give them a good watering. Usually, about an inch of water per week is plenty, especially with our regular rainfall. Water at the base of the plant to avoid wetting the leaves, 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 around the base of the plants can help retain moisture during dry spells and keep the soil cooler during summer heat spells, but don't overdo it.

You can expect your first harvest of Nasturtium flowers and leaves in the Midwest from late June through early October, about 55 days after planting. Both the flowers and leaves are edible and have a peppery flavor that's great in salads and other dishes. The seed pods can also be pickled and used as a caper substitute.

Harvest the flowers when they're fully open and the leaves when they're young and tender. Use scissors or your fingers to gently pluck them off the plant, being careful not to damage the stems. Regular harvesting encourages more flower and leaf production.

As the first frost approaches in early October, harvest any remaining flowers and seed pods. While Nasturtiums are frost-tender, you can often extend the season a bit by covering them on cold nights.

Here are the top three problems you might encounter with Nasturtiums in the Midwest:

Aphids *What it looks like:* Small, pear-shaped insects clustered on stems and leaves, often accompanied by sticky honeydew. *What causes it:* Aphids are attracted to stressed plants, and our variable spring weather can sometimes weaken seedlings. *How to fix/prevent it:* Nasturtiums can actually be used as a trap crop for aphids, drawing them away from other plants. You can also blast them off with a strong stream of water or introduce beneficial insects like ladybugs.

Cabbage Caterpillars *What it looks like:* Green caterpillars chewing holes in leaves, leaving behind droppings. *What causes it:* These caterpillars are the larvae of cabbage white butterflies, which are common in the Midwest. *How to fix/prevent it:* Handpick the caterpillars off the plants or use a biological insecticide like Bacillus thuringiensis (Bt). Covering your plants with row covers can also prevent the butterflies from laying eggs.

Black Fly *What it looks like:* Tiny black insects that suck sap from the plant, causing stunted growth and yellowing leaves. *What causes it:* Black fly thrive in warm, humid conditions, which we definitely experience during our Midwest summers. *How to fix/prevent it:* Similar to aphids, you can blast them off with water or use insecticidal soap. Improving air circulation around the plants can also help.

Midwest Specific Challenges: Our moderate-to-hot heat and moderate-to-humid humidity during the summer can create ideal conditions for pests and diseases. The wet-summer rainfall can also lead to overwatering if you're not careful. Be sure to monitor your plants regularly and adjust your watering schedule as needed.

Nasturtiums make excellent companions for many plants in the Midwest garden. They attract beneficial insects like pollinators and predatory wasps, which can help control pests.

Good companions include:

• Tomatoes: Nasturtiums repel tomato hornworms and other pests that can damage tomato plants.
• Cucumbers: They help deter cucumber beetles, which can transmit diseases.
• Squash: Nasturtiums can attract squash vine borers away from squash plants.
• Broccoli & Cabbage: They act as a trap crop for cabbage white butterflies, protecting these brassicas from cabbage worms.

While there aren't specific "bad" companions, it's best to avoid planting Nasturtiums near plants that prefer very rich soil, as Nasturtiums thrive in slightly poorer conditions.