Sunflower in Zone 5B — Mid-Atlantic

Sunflowers bring a burst of sunshine to any Mid-Atlantic garden. Their towering height and bright blooms add visual interest, and you can harvest the seeds for snacking or roasting. Plus, they attract pollinators that benefit other plants in your vegetable garden, and they're fairly drought-tolerant once established, which is a bonus during our humid summers.

Our four seasons can be a bit unpredictable, but don't let that deter you. Even with our variable spring weather and the potential for late frosts, our 178-day growing season gives you plenty of time to get a sunflower crop going. Just keep an eye on the forecast and adjust your planting schedule accordingly.

Starting sunflowers indoors is possible, but usually not necessary. Since they prefer to be direct-sown, it's best to only start indoors if you're aiming for an exceptionally early bloom. If you choose to start indoors, begin in late March through mid April, roughly three weeks before you plan to transplant.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm and provide plenty of light, either from a sunny window or a grow light. Bottom watering is a great way to keep the soil consistently moist without overwatering. Remember, our spring weather can be moderate, so a little extra warmth indoors helps germination.

Transplant your sunflower seedlings outdoors in late April through late May, once the risk of frost has passed. Before planting them in the ground, be sure to harden them off. This means gradually exposing them to outdoor conditions for about a week, increasing the amount of time each day.

Space your seedlings 18-24 inches apart to give them plenty of room to grow. Keep an eye on the forecast; we sometimes get unexpected cold snaps even in late spring.

Direct sowing is the recommended method for sunflowers in the Mid-Atlantic. Sow seeds directly into the garden from mid April through mid July. Sunflowers are easy to grow this way.

Choose a spot that gets full sun (at least 6-8 hours a day) and prepare the soil by loosening it and adding compost. Soil temperature is important; wait until the soil has warmed up to at least 60°F. Sow seeds 1 inch deep and space them 18-24 inches apart.

Sunflowers need moderate watering, but they're surprisingly drought-tolerant once they establish a deep taproot. In the Mid-Atlantic, with our humid summers and even rainfall, it's important to avoid overwatering.

During the active growing season, check the soil moisture regularly. Stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. Aim for about 1 inch of water per week, including rainfall. Water at the base of the plant rather than overhead to minimize the risk of fungal diseases, which thrive 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, especially useful in our climate with moderate-to-hot heat and even rainfall.

In the Mid-Atlantic, you can expect your first sunflower harvest from early July through mid October. For harvesting seeds, wait until the back of the flower head turns brown and the seeds are plump and slightly loose.

To harvest the seeds, cut the entire flower head off the stalk, leaving about a foot of stem. Hang the head upside down in a dry, well-ventilated place to dry completely. For cut flowers, harvest when the petals first open for the longest vase life.

As our first frost approaches around mid- October, harvest any remaining flower heads that are close to maturity. You can bring them indoors to finish drying, though they will not ripen significantly off the vine.

Here are three common sunflower problems we deal with in the Mid-Atlantic:

Birds Eating Seeds

• What it looks like: Missing seeds from the flower head, often with signs of pecking.
• What causes it: Birds are attracted to the ripe seeds, especially as other food sources become scarce.
• How to fix/prevent it: Cover the flower heads with netting or burlap bags once the seeds start to mature. You can also try using bird feeders away from your sunflowers to distract them.

Sunflower Moth

• What it looks like: Webbing on the flower head, damaged seeds, and small caterpillars inside the flower.
• What causes it: Sunflower moths lay their eggs on the flower heads, and the larvae feed on the seeds.
• How to fix/prevent it: Inspect flower heads regularly for signs of infestation. Remove and destroy any affected heads. Encourage beneficial insects that prey on sunflower moths.

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. Our humid summers are perfect for this.
• 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 heat, humid humidity, and even rainfall create conditions that favor fungal diseases like downy mildew. Monitor your plants closely and take preventative measures to minimize problems. Deer pressure can also be a problem, so consider fencing or deer repellent if they're common in your area.

Sunflowers make great companions for several plants in the Mid-Atlantic garden. Cucumbers and squash benefit from the shade provided by sunflowers during our humid summers. Green beans can climb up the sunflower stalks, saving space and improving air circulation. Corn also grows well alongside sunflowers, as they have similar nutrient needs. Lettuce benefits from the partial shade sunflowers provide, which can prevent bolting in warmer weather. Avoid planting potatoes near sunflowers, as they can inhibit each other's growth.