Arugula in Zone 9A — Texas

Arugula, with its peppery bite, adds a unique flavor to salads and sandwiches that you just can't get from store-bought greens. Growing your own arugula in Texas means fresh, flavorful leaves right outside your door, especially welcome during our two tomato seasons when you’re looking for something to spice up your BLTs. It's a fast-growing crop that rewards you quickly, making it perfect for squeezing in between other plantings.

Texas weather can be unpredictable, with our brutal summer heat and occasional surprise freezes, but arugula thrives when planted at the right time. With our long growing season of 293 days, you can easily grow arugula during the cooler months for a continuous supply of fresh greens.

Starting arugula indoors is possible, but honestly, direct sowing is usually the way to go here in Texas. If you want a head start, though, start your seeds indoors from early to late January, about three weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light, either from a grow light or a sunny window. Bottom watering helps prevent damping off; just set the tray in a shallow dish of water until the soil surface is moist. Given our early spring character, starting indoors can give you a jump, but be ready to harden them off quickly as temperatures rise.

Transplant your arugula seedlings outdoors from early February through mid March. This gives them a chance to establish before the Texas heat really kicks in.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Space them about 6 inches apart in well-drained soil. Keep an eye on the forecast – those unpredictable freezes can still happen, so be ready to cover them if necessary.

Direct sowing arugula is super easy and generally the preferred method for Texas gardeners. Sow seeds from mid January through mid October for a continuous harvest.

Prepare your soil by loosening it and adding some compost. Arugula prefers soil temperatures between 45°F and 65°F for optimal germination. Sow seeds about ¼ inch deep and 6 inches apart. Since arugula bolts in the heat, focus on planting during the cooler parts of the year to get the best flavor and longest harvest.

Arugula needs consistent moisture to thrive, but be careful not to overwater, especially with our variable humidity. Aim to keep the soil consistently moist, but not soggy.

During the spring and fall, when temperatures are milder, water deeply about once or twice a week, depending on rainfall. In the hotter months, you might need to water every day or every other day to prevent bolting. Stick your finger about 2 inches into the soil – if it feels dry, it's time to water. Aim for about 1 inch of water per week.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases, especially when humidity is high. Yellowing leaves can indicate overwatering, while wilting leaves mean it's time to water. A layer of mulch can help retain moisture and regulate soil temperature, which is especially helpful during our hot summers.

You can expect your first arugula harvest in late February through mid December, about 40 days after planting. Arugula is ready to harvest when the leaves are 2-3 inches long for a milder flavor, or larger if you prefer a more peppery taste.

Harvest the outer leaves by snipping them off at the base of the plant, leaving the inner leaves to continue growing. Avoid harvesting after the plant starts to flower, as the leaves will become bitter. With regular harvesting, arugula will continue to produce throughout the season.

As the first frost approaches in early December, harvest any remaining leaves to enjoy. You can also cover the plants to extend the harvest a bit longer if the freeze is light.

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, especially on young seedlings. You might see small, dark beetles that jump when disturbed.
• What causes it: Flea beetles are small jumping beetles that feed on leaves. They are most damaging to small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger. You can also try coating the leaves with kaolin clay or spraying with neem oil. Interplanting with basil or catnip can also help deter them. Healthy, vigorous plants can 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.
• What causes it: Arugula is a cool-season crop and bolts (goes to seed) when temperatures rise consistently above 80°F.
• How to fix/prevent it: Time your plantings for the cooler parts of the year (spring and fall). Choose bolt-resistant varieties. Provide shade during warm spells and use 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 also see a sticky honeydew residue and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather.
• How to fix/prevent it: Knock them off with a strong water spray. Encourage natural predators like ladybugs and lacewings. Insecticidal soap or neem oil can be used for heavy infestations. Avoid excess nitrogen fertilizer, as it 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: Downy mildew is a disease 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.

Texas Specific Challenges: The hot-to-extreme heat of Texas summers, combined with variable humidity and unpredictable rainfall, can make growing arugula challenging. Bolting is a major concern, so timing your plantings and providing shade are crucial. Be vigilant about watering during dry spells, but avoid overwatering in humid conditions to prevent fungal diseases. And always watch out for those fire ants when you're tending your garden!

Arugula benefits from companion planting. Lettuce and spinach make good companions because they share similar growing requirements and can help provide shade for each other. Carrots and beets also work well, as they don't compete for the same nutrients and can help loosen the soil. Onions deter pests and can improve the overall health of your arugula.

Avoid planting arugula near strawberries. Strawberries are susceptible to verticillium wilt, which can also affect arugula, so it's best to keep them separated.