Sunflower in Zone 7B — Mid-Atlantic

Sunflowers bring a real taste of sunshine to our Mid-Atlantic gardens. They’re beautiful, provide seeds for snacking (for you and the birds!), and make a striking statement in any flower bed. Plus, they're surprisingly easy to grow here, even with our humid summers and variable spring weather.

Our 214-day growing season gives you plenty of time to get sunflowers established. Don't let challenges like deer pressure or the occasional late frost scare you off. With a little planning and attention to timing, you can enjoy these beauties from mid-summer well into the fall.

Starting sunflower seeds indoors is an option, but honestly, it's usually not necessary in our climate. Direct sowing works so well! However, if you want a head start or are concerned about early-season pests, you can start seeds indoors from mid-March through early April. This gives you about a 3-week jump on the season.

Use seed trays filled with a good seed-starting mix, and keep them warm (around 70°F) and well-lit. Bottom watering will help prevent damping off, which can be a problem in our sometimes-humid spring air. Just set the tray in a shallow dish of water and let the soil absorb it from the bottom.

If you started your sunflowers indoors, aim to transplant them outdoors from early April through early May. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space the seedlings 18-24 inches apart in a sunny spot. Keep an eye on the weather forecast; we sometimes get a late frost in April, so be ready to cover your young plants if needed.

Direct sowing is the easiest and most common way to grow sunflowers here in the Mid-Atlantic. You can sow seeds directly into the garden from early April through late July. This gives you a long window for succession planting and extends your harvest.

Choose a spot with full sun and well-drained soil. Sunflowers aren't too picky, but they appreciate a little compost worked into the soil before planting. Sow seeds about 1 inch deep and space them 18-24 inches apart. They germinate best when the soil temperature is consistently above 60°F. Keep the soil consistently moist until seedlings emerge, which usually takes about a week.

Sunflowers are fairly drought-tolerant once they’re established, thanks to their deep taproots. However, consistent watering is key, especially during our humid summers. The trick is to water deeply but infrequently.

During the hotter months, check the soil moisture regularly. Stick your finger about 2 inches into the soil near the base of the plant. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

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 helps retain moisture and suppress weeds, which is especially helpful in our sometimes-clay soil.

You can expect your first sunflower harvest from mid-June through early November, depending on when you planted. Sunflowers typically take about 80 days to mature. For seeds, wait until the back of the flower head turns brown and the seeds are plump and slightly loose.

To harvest seeds, cut the entire head off the plant, leaving about a foot of stem. Hang the head upside down in a well-ventilated place to dry completely. For cut flowers, cut the stems when the petals first open, ideally in the morning.

As our first frost approaches in early November, harvest any remaining flower heads, even if they aren't fully mature. You can still dry the seeds indoors, or leave the heads out for the birds to enjoy over the winter.

Here in the Mid-Atlantic, we face a few common sunflower challenges: birds eating the seeds, sunflower moths, and downy mildew.

Birds Eating Seeds

• What it looks like: Sunflower heads with missing or pecked-at seeds. You might see birds actively feeding on the plants.
• What causes it: Birds are attracted to the ripening seeds, especially as other food sources become scarce.
• How to fix/prevent it: Cover the flower heads with netting or paper bags once the petals start to dry out. You can also try planting extra sunflowers specifically for the birds.

Sunflower Moth

• What it looks like: Small, gray moths flying around the sunflower heads. You might see larvae (caterpillars) feeding on the seeds and webbing inside the flower head.
• What causes it: Sunflower moths lay their eggs on the developing flower heads. The larvae hatch and feed on the seeds, causing damage and reducing yield.
• How to fix/prevent it: Inspect your plants regularly for signs of moth activity. Remove any larvae you find. You can also use insecticidal soap or Bacillus thuringiensis (Bt) 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.

Mid-Atlantic Specific Challenges: Our moderate-to-hot summers, humid humidity, and even rainfall can create ideal conditions for fungal diseases like downy mildew. Good air circulation and proper watering techniques are essential for preventing these problems. Deer pressure is also a concern, so consider fencing or using deer repellent to protect your plants, especially when they are young.

Sunflowers make great companions for several plants in the Mid-Atlantic garden. Cucumbers and squash benefit from the sunflower's shade during our hot summers. Green beans can climb up the sturdy sunflower stalks, saving space. Corn and sunflowers are classic companions, as they both thrive in similar conditions. Lettuce planted near sunflowers can enjoy some protection from the intense afternoon sun. Avoid planting potatoes near sunflowers, as they can compete for nutrients and inhibit each other's growth.