Sunflower in Zone 8B — Texas

Sunflowers are a fantastic addition to any Texas garden. Their towering height and bright, cheerful blooms add beauty, and you can harvest the seeds for snacks or roasting. Plus, they attract pollinators, which is always a win in our gardens.

Our unpredictable weather can be a challenge, but sunflowers are surprisingly resilient. With a long growing season like ours (around 273 days), you have plenty of time to get them established and enjoy their sunshiney goodness.

Starting sunflower seeds indoors isn't essential, but it can give you a head start, especially if we have a late cold snap. Starting seeds indoors from early to late February, about three weeks before you plan to transplant, is the way to go. Use seed trays with a good seed-starting mix, and keep them warm and well-lit, preferably with a grow light.

Bottom watering is your friend to prevent damping off. Place the tray in a shallow dish of water and let the soil soak it up from the bottom. Since our spring weather can be so early, starting indoors buys you some time.

Transplant your sunflower seedlings outdoors from early March through early April, once the danger of a hard freeze has passed. 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 wind.

Space them 18-24 inches apart to give them plenty of room to grow. Keep an eye on the forecast; even in March, we can still get a cold snap that can set them back.

Direct sowing is the easiest and most common way to grow sunflowers here in Texas. Sow your seeds directly into the ground from late February through late August. Sunflowers are easy to direct sow and grow quickly.

Choose a spot with full sun and well-drained soil. Before planting, loosen the soil and amend it with compost. The soil temperature should be at least 60°F for best germination. Plant the seeds about 1 inch deep and space them 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge.

Sunflowers need moderate watering, but once they're established, they're surprisingly drought-tolerant thanks to their deep taproot. Here in Texas, that's a huge plus.

During the hottest part of the summer, especially if we're in a dry spell, water deeply about once a week, providing about 1-2 inches of water. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Water at the base of the plant to avoid getting the leaves wet, which can encourage fungal diseases, especially with our variable humidity.

Yellowing leaves can indicate overwatering, while drooping leaves signal underwatering. A good layer of mulch around the base of the plants will help retain moisture and keep the soil cool during our brutal Texas heat.

You can expect your first sunflower harvest from mid-May through late November, about 80 days after planting.

For harvesting seeds, wait until the back of the flower head turns brown and the seeds are plump and slightly loose. You can cover the flower head with cheesecloth or a paper bag to protect the seeds from birds. To harvest, cut the flower head off the stalk and hang it upside down in a dry, well-ventilated place until the seeds are completely dry. For cut flowers, harvest when the petals first open.

As our first frost approaches in late November, harvest any remaining flower heads, even if they're not fully mature. You can still dry the seeds indoors.

Here are some common problems you might encounter with sunflowers in Texas:

Birds Eating Seeds

• What it looks like: Sunflower heads with missing seeds or signs of pecking.
• What causes it: Birds love sunflower seeds.
• How to fix/prevent it: Cover the flower heads with netting, cheesecloth, or paper bags once the seeds start to mature. You can also try using bird deterrents like shiny tape or scarecrows.

Sunflower Moth

• What it looks like: Small caterpillars inside the sunflower head, damaging the seeds and causing the head to rot.
• What causes it: Sunflower moths lay their eggs on the flower heads, and the larvae hatch and feed on the seeds.
• 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 larvae.

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 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 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. Ensure they get adequate water, especially during dry spells, and provide afternoon shade if possible. Keep an eye out for those fire ants, too, as they can disrupt the soil around your plants.

Sunflowers make great companions for several plants. Cucumbers and squash benefit from the shade provided by sunflowers, which helps keep the soil cool and moist during our hot summers. Green beans can use the sunflower stalks as a natural trellis. Corn and sunflowers are classic companions, as they both benefit from similar growing conditions. Lettuce can benefit from the partial shade offered by sunflowers, preventing it from bolting in the heat.

Avoid planting potatoes near sunflowers, as they can compete for nutrients and stunt each other's growth.