Arugula in Zone 7A — Midwest

Arugula is a fantastic addition to any Midwest garden. Its peppery bite adds a delicious kick to salads, pizzas, and pestos, and it thrives in our fertile soil and enjoys the adequate rainfall we get during the growing season. Plus, the satisfaction of harvesting fresh greens just weeks after planting is hard to beat.

Our Midwest weather can be unpredictable, with variable springs and occasional summer heat spells. However, with a little planning and attention to timing, you can easily enjoy a bountiful harvest of arugula throughout our 193-day growing season.

Starting arugula indoors is possible, but honestly, direct sowing is usually the way to go here in the Midwest. If you want a super early start, you can sow seeds indoors from late February through mid March, about 3 weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light, either from a grow light or a sunny windowsill. Bottom watering is a great way to keep the soil evenly moist without overwatering. Keep in mind that our springs can be moderate-to-late, so don't rush to get them outside too soon.

Transplanting arugula seedlings outdoors can be done from late March through early May. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space your plants about 6 inches apart in well-drained soil. Keep an eye on the weather, especially for any unexpected cold snaps that might nip those young plants.

Direct sowing arugula is incredibly easy and often the preferred method for Midwest gardeners. You can sow seeds directly into the garden from mid March through late August for a continuous supply of fresh greens.

Prepare the soil by loosening it and removing any rocks or debris. Sow seeds about ¼ inch deep and space them about 6 inches apart. Arugula is fast-growing, but it can bolt in the heat, so focus on planting during cooler periods for the best results.

Arugula needs moderate watering to thrive in the Midwest. While we often get plenty of rainfall, it's important to keep the soil consistently moist, especially during dry spells.

During the spring and fall, when temperatures are cooler, you may only need to water once or twice a week, depending on rainfall. In the summer, with our moderate-to-hot heat and moderate-to-humid humidity, you might need to water every other day, or even daily during heat spells. Stick your finger about 2 inches deep into the soil – if it feels dry, it's time to water. Aim for about 1 inch of water per week, including rainfall.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our humid conditions. Signs of underwatering include wilting leaves and slow 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.

You can expect your first harvest of arugula about 40 days after planting, which means from late April through late October here in the Midwest. The best time to harvest is when the leaves are young, around 2-3 inches long, for a milder flavor. Larger leaves will have a more peppery taste.

Harvest by snipping off the outer leaves with scissors, leaving the inner leaves to continue growing. This encourages continuous production throughout the season. As the first frost approaches in mid- October, harvest any remaining leaves to enjoy before the cold weather sets in.

Here are some common problems you might encounter growing arugula in the Midwest:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves, especially on young seedlings. You might see small, dark beetles jumping when disturbed.
• What causes it: Small jumping beetles that feed on leaves. They're most damaging to small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings during their vulnerable stage. Delay planting until plants are larger. You can also try a kaolin clay coating or neem oil spray. Interplanting with basil or catnip may help deter them. Healthy, vigorous plants often outgrow the damage.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk, and the leaves become tough and bitter. The harvest quality declines.
• What causes it: Extended warm temperatures trigger bolting. Arugula is a cool-season crop and bolts when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cooler weather in spring and fall. Choose bolt-resistant varieties if available. Provide shade during summer heat spells. Mulch to keep the soil cool. Harvest frequently to encourage leaf production before bolting progresses.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. You might see sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Knock them off with a strong water spray. Encourage ladybugs and lacewings (natural predators). Insecticidal soap can be used for heavy infestations. Neem oil also works systemically. Avoid excess nitrogen fertilizer, which attracts them.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on undersides. Leaves brown and die from the bottom up.
• What causes it: An oomycete pathogen that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around the plants. Water at the base, never overhead. Copper-based fungicides can be used for prevention. Plant resistant varieties where available.

Midwest Specific Challenges: Our moderate-to-hot summer heat, moderate-to-humid humidity, and wet-summer rainfall can create ideal conditions for bolting and fungal diseases like downy mildew. Careful attention to watering, timing, and variety selection is key to success.

Arugula benefits from companion planting. Lettuce and spinach are good companions because they share similar growing requirements and won't compete for resources. Carrots and beets are also beneficial, as their root systems help to loosen the soil, improving drainage for the arugula. Onions can help deter pests like aphids. Avoid planting arugula near strawberries, as they can attract slugs and snails, which can also damage the arugula.