Arugula in Zone 7A — Texas

Arugula is a fast-growing, peppery green that adds a zesty kick to salads and sandwiches. It's a great choice for Texas gardeners because you can squeeze in multiple harvests during our long growing season, especially with our mild winters. Plus, the fresh taste beats anything you'll find at the grocery store, especially after it's been trucked here in the Texas heat.

Even with our 245-day growing season, gardening in Texas comes with challenges like extreme heat and unpredictable weather. But with careful timing and a little extra attention, you can enjoy a steady supply of homegrown arugula. You can plant early, harvest early, and keep your plants happy.

Starting arugula indoors is an option, especially if you want a head start for an early spring harvest. Begin sowing seeds indoors from early to late February, about three weeks before you plan to transplant them outside. Use seed trays or small pots filled with a good seed-starting mix, and keep them in a warm location with plenty of light, either from a sunny window or a grow light.

Bottom watering is the way to go. Set the trays in a shallow pan of water until the soil surface is moist. Texas weather can be unpredictable, so starting indoors gives you a safety net in case of a late freeze.

Transplant your arugula seedlings outdoors from early March through mid April, after they've developed a few sets of true leaves. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas elements, including wind and temperature fluctuations.

Space the plants about 6 inches apart in well-drained soil. Keep an eye on the forecast – we can still get some unexpected cold snaps that time of year, even though our spring comes early.

Direct sowing arugula is easy and often the preferred method here in Texas. Sow seeds directly into the garden from mid February through late September. Arugula germinates best in cool soil, so aim for a soil temperature between 45°F and 75°F.

Prepare the soil by loosening it and adding compost for extra nutrients. Sow seeds about ¼ inch deep and 6 inches apart. Arugula bolts quickly in the heat, so direct sowing is best for spring and fall crops when the weather is cooler.

Arugula needs consistent moisture to thrive, but it doesn't like to be waterlogged. During the spring and fall, when temperatures are milder, aim to water deeply about once a week, providing about 1 inch of water. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

In the summer, especially with our hot-to-extreme heat, you might need to water more frequently, possibly every other day, depending on rainfall. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases, especially with our variable humidity.

Signs of underwatering include wilting leaves and a more intense, bitter flavor. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, like shredded bark or straw, can help retain moisture in the soil and regulate soil temperature, which is a big help during our hot summers.

You can expect your first arugula harvest about 40 days after planting. Here in Texas, that means you could be harvesting from late March through late November, depending on when you planted. Look for leaves that are about 2-3 inches long for a milder flavor, or let them grow larger for a more peppery taste.

Harvest the outer leaves by snipping them off at the base of the plant. This allows the inner leaves to continue growing, giving you a continuous harvest. Keep harvesting until the plant starts to bolt (send up a flower stalk), as the leaves become bitter at that point.

As the first frost approaches in mid- November, harvest any remaining leaves to enjoy before the cold weather sets in. Arugula can often withstand a light frost, but the flavor may be affected.

Arugula is relatively easy to grow, but here are a few common problems you might encounter in Texas:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in the leaves. You'll see small, dark beetles that jump when disturbed. Young seedlings are most at risk.
• What causes it: These small jumping beetles feed on the leaves. They love brassicas and other crops. They're especially bad on small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger and stronger. Kaolin clay coating can deter them. Neem oil spray can help. Interplant with basil or catnip. Healthy, vigorous plants can usually outgrow the damage.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk when temperatures rise. The leaves become tough and bitter.
• What causes it: Extended warm temperatures above the plant's comfort zone. Arugula bolts when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cooler weather (spring and fall). Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest leaves frequently 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. Their populations explode in warm weather. Ant colonies may "farm" them for honeydew.
• How to fix/prevent it: A strong water spray can knock them off. Encourage ladybugs and lacewings (natural predators). Use insecticidal soap for heavy infestations. Neem oil 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. Water at the base, never overhead. Copper-based fungicides can help prevent it. Plant resistant varieties if you can find them.

Texas Specific Challenges: Our hot-to-extreme heat, variable humidity, and unpredictable rainfall can all contribute to these problems. The heat encourages bolting and aphid infestations, while humidity can worsen downy mildew. Keeping a close eye on your plants and adjusting your watering and pest control strategies accordingly is key to success. Fire ants won't directly attack arugula, but they can disrupt the soil and spread aphids, so keep them in check, too.

Arugula plays well with several other plants in the garden. Lettuce and spinach are good companions because they have similar growing requirements and can provide shade for each other during the hottest part of the day. Carrots and beets are also beneficial companions; they help loosen the soil and don't compete for the same nutrients. Onions can deter pests like aphids.

Avoid planting arugula near strawberries. Strawberries are prone to fungal diseases that can spread to arugula, especially in our humid Texas conditions.