Sunflower in Zone 7A — Midwest

Sunflowers are a fantastic addition to any Midwest garden. Not only are they beautiful and attract pollinators, but you can also harvest the seeds for a tasty snack or to feed the birds during our cold winters. Plus, nothing says summer in the Midwest like a towering sunflower!

While we do have to contend with variable spring weather and the occasional summer heat spell, sunflowers are surprisingly easy to grow here. With a 193-day growing season, you've got plenty of time to get them in the ground and enjoy their sunny faces.

Starting sunflower seeds indoors is an option, but not usually necessary in the Midwest. Since we have a decent growing season and sunflowers sprout easily, direct sowing is generally the way to go. However, if you're eager to get a head start, or want to ensure blooms for a special event, you can start them indoors.

Start seeds mid-March through early April, about three weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light – a sunny windowsill or grow light works well. Remember to bottom water to avoid damping off, which can be an issue in our moderate-to-late springs.

If you started your sunflower seeds indoors, you can transplant them outdoors mid-April through mid-May, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Midwest weather, which can still be a bit unpredictable that time of year.

When transplanting, space the seedlings 18-24 inches apart. Choose a sunny spot with fertile soil. Keep an eye on the weather forecast and be prepared to cover them if a late frost is predicted.

Direct sowing is the easiest and most common way to grow sunflowers in the Midwest. Sow seeds early April through mid-July for a continuous display of blooms. Sunflowers grow quickly, so even a later sowing will give you plenty of flowers before our first frost in mid- October.

Prepare the soil by loosening it and mixing in some compost. Ensure the soil temperature is at least 50°F. Plant seeds 1 inch deep and space them 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge. Sunflowers are easy to direct sow and grow quickly, so you'll be enjoying their sunny faces in no time.

Sunflowers need moderate watering, but they're also surprisingly drought-tolerant once established, thanks to their deep taproot. In the Midwest, we have wet-summer rainfall, so you don't need to water constantly.

During the early stages, water deeply whenever the top 2 inches of soil feel dry to the touch – use the finger test! Typically, this means about 1 inch of water per week, especially during hot summer spells. Once they're established, you can usually reduce watering frequency. Water at the base of the plant to avoid getting the leaves wet, which can lead to fungal diseases in our moderate-to-humid climate.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can cause root rot, indicated by yellowing leaves and a soft, mushy stem. A layer of mulch around the base of the plant helps retain moisture and suppress weeds, which is especially helpful in our fertile soil.

You can expect your first sunflower harvest late June through mid-October, about 80 days after planting. For seeds, wait until the back of the flower head turns brown and the seeds are plump and slightly loose. You can cut the entire head off and hang it upside down in a dry, well-ventilated place 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 the first frost approaches in mid- October, harvest any remaining heads, even if they're not fully ripe. You can let them dry indoors.

Here are a few common problems you might encounter with sunflowers in the Midwest:

Birds eating seeds

• What it looks like: Sunflower heads with missing or pecked-at seeds.
• What causes it: Birds love sunflower seeds!
• How to fix/prevent it: Cover the 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: Webbing and larvae inside the flower head. Seeds may be damaged or hollow.
• What causes it: Sunflower moths lay their eggs on the developing flower heads.
• How to fix/prevent it: Remove any infested heads. Encourage beneficial insects like lacewings and ladybugs. You can also apply 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. Different species affect different plants.
• 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.

Midwest Specific Challenges: Our moderate-to-hot heat and moderate-to-humid humidity, combined with wet-summer rainfall, can create ideal conditions for fungal diseases like downy mildew. Proper spacing and watering practices are key to prevention.

Sunflowers make great companions for many plants in the Midwest garden. Cucumbers and squash benefit from the shade provided by the tall sunflowers. Green beans can use the sunflower stalks for support. Corn and sunflowers are classic companions, as they both thrive in our fertile soil and full sun. Lettuce can benefit from the partial shade provided by sunflowers during the hottest part of the summer.

Avoid planting potatoes near sunflowers. Potatoes are susceptible to similar fungal diseases, and planting them together can increase the risk of infection.