Sunflower in Zone 8A — Texas

Sunflowers are a fantastic addition to any Texas garden, offering beauty, edible seeds, and even cut flowers. With our long growing season, you can enjoy multiple harvests, attracting pollinators and adding a cheerful splash of color to your landscape even through the brutal Texas heat.

While Texas weather can be unpredictable, don't let that discourage you. Our 260-day growing season gives you plenty of time to plant, grow, and harvest sunflowers successfully. Smart timing and a little planning will help you overcome the challenges.

Starting sunflower seeds indoors is an option, especially if you're aiming for an extra-early bloom. Begin in mid February through early March, about three weeks before you plan to transplant. Use seed trays with a good seed-starting mix and keep them warm and well-lit.

Bottom watering is key to avoid damping off; set the tray in a shallow dish of water and let the soil absorb moisture from the bottom. Given our early springs in Texas, this indoor start can give you a head start, but direct sowing is generally preferred.

Transplant your sunflower seedlings outdoors from mid March through early April, once the soil has warmed up. 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 allow for adequate growth. Keep an eye on the weather forecast; those unpredictable late freezes can still happen.

Direct sowing is the easiest and most recommended method for growing sunflowers in Texas. Sow seeds from early March through mid August, giving you ample time for multiple plantings. Ensure the soil temperature is consistently warm, around 60-70°F, for optimal germination.

Prepare the soil by loosening it and adding compost. Plant seeds about 1 inch deep, spacing them 18-24 inches apart. Sunflowers are quick growers, so you'll see sprouts in no time!

Sunflowers are moderately drought-tolerant once established, thanks to their deep taproots. However, consistent watering is crucial, especially during the initial growth stages and during our hot Texas summers. Water deeply but infrequently, allowing the soil to dry out slightly between waterings.

During the spring and fall, aim for about 1 inch of water per week, either from rainfall or irrigation. In the peak of summer, increase this to 1.5-2 inches per week. Use the "finger test" – stick your finger about 2 inches deep into the soil; if it feels dry, it's time to water. Water at the base of the plant to prevent fungal diseases, especially with our variable humidity.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants can help retain moisture and regulate soil temperature, a great strategy for our Texas conditions.

You can expect your first sunflower harvest from late May 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. For cut flowers, harvest when the petals first open.

To harvest seeds, cut the entire flower head and hang it upside down in a dry, well-ventilated place until the seeds are completely dry. As the first frost approaches in mid- November, harvest any remaining heads, even if they aren't fully mature, and dry them indoors to salvage as many seeds as possible.

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

Birds Eating Seeds

• What it looks like: Sunflower heads stripped of seeds, often with visible bird activity around the plants.
• What causes it: Birds are attracted to the readily available seeds, especially as they ripen.
• How to fix/prevent it: Cover the flower heads with netting or mesh bags as the seeds mature. Decoys or reflective tape can also deter birds.

Sunflower Moth

• What it looks like: Small caterpillars inside the flower heads, feeding on seeds and causing damage. You might also see webbing and frass (caterpillar droppings).
• What causes it: Sunflower moths lay their eggs on the flower heads, and the larvae burrow in to feed.
• How to fix/prevent it: Inspect flower heads regularly for signs of infestation. Remove and destroy any infested heads. Bacillus thuringiensis (Bt) can be applied as a preventative measure.

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: Our hot-to-extreme heat can stress sunflowers, making them more susceptible to pests and diseases. Variable humidity can also exacerbate fungal problems. Drought conditions can reduce seed yield. Be vigilant with watering and monitoring your plants to address issues promptly.

Good companion plants for sunflowers in Texas include cucumbers, squash, and green beans. These plants help suppress weeds and provide ground cover, keeping the soil cooler during our hot summers. Corn also makes a good companion, providing support for taller sunflower varieties. Lettuce can be planted around the base of sunflowers to take advantage of the shade they provide.

Avoid planting potatoes near sunflowers, as they can compete for nutrients and attract similar pests.