Arugula in Zone 9B — Texas

Arugula is a fantastic addition to any Texas garden. Its peppery bite adds a zesty flavor to salads and sandwiches, and it's incredibly versatile in the kitchen. Plus, you get the satisfaction of harvesting fresh greens right outside your door, even during our mild winters and extended growing season.

Our unpredictable Texas weather, including the brutal summer heat, can be a challenge for arugula. But with a little planning and attention to timing, you can enjoy a continuous harvest of this delicious green throughout much of our 308-day growing season.

Starting arugula indoors is definitely an option, especially if you want a head start on the season. Begin in late December through mid January – about three weeks before you plan to transplant. Use seed trays or small pots filled with a good seed-starting mix.

Keep the soil consistently moist by bottom watering (set the tray in a shallow dish of water and let the soil absorb it). Provide warmth and plenty of light, either from a sunny windowsill or a grow light. Since spring comes early here, getting a jump start indoors can get you harvesting even sooner.

Transplant your arugula seedlings outdoors in late January through early March. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sunshine and variable temperatures.

Space the seedlings about 6 inches apart in well-drained soil. Keep an eye on the forecast for any late freezes, which can sometimes surprise us. If a freeze is predicted, cover your seedlings with frost cloth to protect them.

Direct sowing is the most common and easiest way to grow arugula here in Texas. Sow seeds directly into the garden from early January through mid October. Prepare the soil by loosening it and removing any rocks or debris.

Arugula germinates best in cool soil (around 60-70°F). Sow seeds about ¼ inch deep and 6 inches apart. Keep the soil consistently moist until the seedlings emerge. Arugula is fast-growing, but it can bolt in the Texas heat, so focus on planting during cooler periods.

Arugula needs consistent moisture to thrive, especially in our Texas climate. During the cooler months (late fall, winter, early spring), aim for about 1 inch of water per week, either from rainfall or irrigation. Check the soil moisture by sticking your finger about 2 inches deep. If it feels dry, it's time to water.

As temperatures rise in late spring and summer, you'll likely need to increase watering to 1-2 inches per week. Water deeply at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our variable humidity. Overhead watering is fine if the humidity is low and you water in the morning, so the leaves can dry quickly.

Signs of underwatering include wilting leaves and a strong, bitter taste. 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 suppress weeds.

You can expect your first arugula harvest about 40 days after planting, usually from mid February through mid December, depending on when you sowed the seeds. Harvest the leaves when they are young and tender, about 2-3 inches long, for a milder flavor. Larger leaves will have a more pronounced peppery taste.

To harvest, simply snip off the outer leaves with scissors or garden shears, leaving the inner leaves to continue growing. This cut-and-come-again method encourages continuous production throughout the season. As the first frost approaches in early December, harvest any remaining leaves to enjoy in salads or pesto.

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

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. Small dark beetles that jump 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. Delay planting until plants are larger. Spray with kaolin clay. Interplant with basil or catnip. Healthy, vigorous plants can often outgrow the damage.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk. Leaves become tough and bitter.
• What causes it: Extended warm temperatures. Arugula bolts when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cooler weather (spring/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. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings. Use insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer.

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: Oomycete pathogen that spreads in cool, humid conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides for prevention. Plant resistant varieties.

Texas Specific Challenges: Our hot-to-extreme heat, variable humidity, and unpredictable rainfall make growing arugula a bit tricky. Bolting is a major concern during the summer, so focus on spring and fall plantings. Keep a close eye on watering, especially during dry spells, but be mindful of humidity to prevent fungal diseases.

Arugula benefits from several companion plants in the Texas garden. Lettuce and spinach are great companions because they share similar growing requirements and can provide shade for arugula during the hottest part of the day. Carrots and beets loosen the soil, improving drainage and aeration for arugula roots. Onions deter pests like aphids that can bother arugula. Avoid planting arugula near strawberries, as they can attract pests that also affect arugula.