Sunflower in Zone 7A — Texas

Sunflowers are a fantastic addition to any Texas garden. They're beautiful, attract pollinators, and you can harvest the seeds for a tasty snack. Plus, watching those towering stalks thrive in the Texas sun is incredibly rewarding.

We all know our Texas weather can be unpredictable, with extreme heat and occasional drought. But with a little planning and attention to timing, you can easily grow sunflowers here. Our long growing season (around 245 days) gives you plenty of opportunity to get them established.

Starting sunflower seeds indoors isn't usually necessary here in Texas, given our long growing season, but it can give you a head start. If you want to get a jump on things, start seeds indoors from late February through mid March. That's about 3 weeks before you'd want to put them in the ground.

Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light—a sunny windowsill or grow lights work well. Bottom watering helps prevent damping-off. With an early spring here in Texas, you'll want to keep an eye on the weather and be ready to harden them off soon.

Transplant your sunflower seedlings outdoors from late March through mid April, once the soil has warmed up a bit. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sun and wind.

Space them 18-24 inches apart to give them room to grow. Keep an eye on the forecast for any late freezes, which can happen even in late March. If a freeze is predicted, cover your young plants to protect them.

Direct sowing is the easiest and most common method for growing sunflowers in Texas. You can direct sow from mid March through mid August. Sunflowers are very easy to direct sow and grow quickly.

Choose a sunny spot with well-drained soil. Prepare the soil by loosening it and mixing in some compost. Sow seeds 1-2 inches deep and space them 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge.

Sunflowers are moderately drought-tolerant once they're established, thanks to their deep taproots. But during our hot Texas summers, they'll still need consistent watering, especially when young. Water deeply but infrequently, encouraging those roots to dig down.

During the spring and fall, when temperatures are milder, water once or twice a week, depending on rainfall. In the heat of summer, you might need to water every other day, or even daily if it's exceptionally hot and dry. Stick your finger about 2 inches into the soil—if it feels dry, it's time to water. Aim for about 1-2 inches of water per week, either from rain or irrigation. Water at the base of the plants to avoid wetting the foliage, especially with our variable humidity, which can encourage fungal diseases.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so watch out for yellowing leaves and mushy stems. Mulching around your sunflowers with a layer of organic material like shredded bark or compost helps retain moisture and suppress weeds, which is always a plus in Texas gardens.

You can expect your first sunflower harvest from early June through mid November, depending on when you planted. For harvesting seeds, wait until the back of the flower head turns brown and the seeds are plump and slightly loose.

To harvest, cut the entire flower head off the stalk with a few inches of stem attached. You can then hang the head upside down in a dry, well-ventilated place to allow the seeds to dry completely. For cut flowers, harvest when the petals first open. Cut the stem at an angle and place the flowers in water immediately.

As our first frost approaches in mid- November, harvest any remaining flower heads, even if they're not fully mature. You can still dry the seeds indoors or enjoy the flower heads for their ornamental value.

Here are three common problems you might encounter growing sunflowers in Texas:

Birds Eating Seeds

• What it looks like: Sunflower heads with missing or damaged seeds. You might see birds pecking at the heads.
• What causes it: Birds love sunflower seeds! They're especially attracted to ripening seeds in the fall.
• How to fix/prevent it: Cover the flower heads with netting or paper bags once the petals start to dry. You can also try using bird deterrents like reflective tape or decoys.

Sunflower Moth

• What it looks like: Small caterpillars inside the sunflower head, often accompanied by webbing and frass (caterpillar droppings).
• What causes it: Sunflower moths lay their eggs on the developing flower heads. The caterpillars then feed on the seeds and other flower parts.
• How to fix/prevent it: Inspect flower heads regularly for signs of infestation. Remove and destroy any infested heads. You can also use insecticidal soap or Bacillus thuringiensis (Bt) to control the caterpillars.

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 caused by 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 your plants by spacing them properly. 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 and variable humidity in Texas can stress sunflowers, making them more susceptible to pests and diseases. Unpredictable rainfall can also be a challenge, as both drought and flash floods can damage plants. Make sure to choose a well-drained location and water consistently, especially during dry spells.

Sunflowers make great companions for several plants in the Texas garden. Cucumbers and squash benefit from the sunflowers' shade, which helps protect them from the intense afternoon sun. Green beans can use the sunflower stalks as a natural trellis. Corn and sunflowers are classic companions, as they both enjoy similar growing conditions. Lettuce appreciates the partial shade provided by sunflowers, especially during the hottest part of the summer.

Avoid planting potatoes near sunflowers. Potatoes are heavy feeders and can compete with sunflowers for nutrients in the soil.