How to Care for Sunflowers

Sunflowers are magnificent flowers, featuring thousands of tiny blooms arranged in a circular disk at the center. Many common sunflower varieties grow rapidly, are drought-tolerant, and are resistant to diseases. Protect your plants from pests and shield them from strong winds, and you'll enjoy a stunning garden throughout the summer.

Select a variety. Sunflowers come in many varieties, ranging from tall plants that grow up to 5.5 meters to shorter bush-like plants with flower heads resembling pom-poms. Besides size and shape, here are other factors to consider:

• The classic yellow sunflower variety typically grows very quickly with a single stem, making it easy to grow. Varieties like Sunrich and Pro Cut are ideal for beginners.
• Branching sunflowers can produce multiple flowers from each seed, but they tend to grow slower. If you're planning to harvest flowers, choose a variety with little or no pollen, like Cherry Rose, to avoid mess.
• Large sunflower varieties such as Mammoth Gray Stripe and Humongous often yield tastier seeds and provide stronger support for climbing plants. (Some smaller varieties may only produce seeds suitable for bird food.)

Determine the best time to plant sunflowers. Sunflowers can be planted starting at the end of spring, once the last frost has passed. However, many varieties sensitive to daylight may grow thin and flower slowly if not planted at the right time. There are 3 main types of sunflowers:

• Short day plants: These need long nights to trigger blooming. It's best to plant them late in summer (or start indoors by mid-spring).
• Long day plants: These typically bloom in mid-summer.
• Intermediate day plants: These can be planted at any point during the growing season.
• Plan ahead based on when the flowers bloom. Most sunflower varieties with a single stem will bloom about 60 days after sowing, while branching sunflowers take about 90 days.

Select a well-drained, fully sunny area. Sunflowers thrive when planted in loose, well-drained soil with a neutral pH. More importantly, they need a location that receives full sun for at least 6 hours a day, with 8 hours or more being even better.

• If the soil is poor, mix in 7-10 cm of compost into the surface layer of soil.

Sow the seeds. Growers typically plant large-flowered sunflowers with a single stem at a depth of at least 2.5 cm. In a home garden with quality soil (not too dry or sandy), you can plant the seeds deeper, around 1 cm.

• Plant extra seeds if there’s space. You can thin them out once the seedlings emerge, and keep in mind that some seeds might be lost to pests.

Space seeds based on the size of the flower you want to grow. The more space between the plants, the larger the flowers will be:

• Plant seeds 15 cm apart for small flowers, ideal for making bouquets, or 23 cm or more for larger blooms.
• If the variety you’re planting grows taller than 1.5 meters, space the plants at least 30 cm apart. Giant sunflower varieties may need as much as 50 cm of space.
• Most branching sunflower varieties need about 45 cm between plants.

Water the seedlings daily. Sunflower seedlings in the rooting phase need plenty of water. Keep the soil moist but not soggy until the seedlings emerge, which usually takes 5-10 days, though it could take longer in cooler weather. Once the seedlings sprout, water them about 7.5-10 cm away from the base to encourage root development.

Fertilize if the soil is poor. Sunflowers don’t require much fertilizer, and excess nitrogen can cause weak growth and slow blooming. If your soil is lacking nutrients, you can add compost or slow-release fertilizer to the surface. This will help the plants grow stronger without over-fertilizing.

Protect the plants from pests. Protecting the plants from snails and slugs is especially important. You can use store-bought snail repellents or create a DIY 'beer trap' to catch them.

Pay attention to yellowing leaves. Powdery mildew is a major issue for plants grown in clay or waterlogged soil. In addition to the obvious symptoms of this fungal disease, you should regularly check for curled or yellowing leaves. If you notice these signs, reduce watering to let the soil dry out and use fungicide immediately. Infected plants rarely bloom, so it might be best to remove the diseased plants to prevent spreading to healthy ones.

• If the leaves appear generally healthy but have an unusual yellowish tint, the plant may be infected with bacteria rather than fungus. Keeping the soil dry will help, and typically, the plant will recover.
• If the leaves turn yellow but the veins remain green, the issue is likely nutrient deficiency. While diagnosing the exact cause can be tricky, diluted fertilizer may help.
• Note that it’s normal for sunflowers to shed their first pair of leaves as they begin rooting. Don’t worry if the lower leaves turn yellow and fall off while the remaining leaves stay healthy.

Reduce watering once the plants mature. Sunflowers are quite drought-tolerant once their taproots have established deep into the soil. They will still thrive with regular, deep watering, especially during the budding and blooming phases, but it’s important to let the soil dry out between waterings. Over-watering is usually more harmful than underwatering.

• Avoid getting the flowers wet to prevent damage.

Stake the plants in windy areas. Wind can severely damage most branching varieties and plants taller than 90 cm. Use fabric or soft materials to tie the plant's stem to sturdy stakes. If the sunflowers grow too tall, you may also need to set up a windbreak to shield them.

Cut flowers when they bloom ¼ of the way. At this stage, the petals will extend perpendicularly from the central disk. It’s best to cut the flowers now to ensure they last longer (usually 5 days, although some varieties last even longer):

• Cut flowers in the early morning or just before dusk.
• Use a clean knife or scissors to cut the stem.
• Remove any leaves below the waterline in the vase.
• Place the flowers in water immediately.

Cut flowers to dry them. In this case, it’s best to wait until the flowers have bloomed halfway, and the petals are starting to curl outward. After cutting, there are several ways to preserve the flowers. The simplest method is to tie the stems together with string and hang them upside down in a warm, well-ventilated room.

Protect the seeds from birds and squirrels. If you want to harvest the seeds yourself, you’ll need to battle with the critters lurking around. Use paper bags or mesh fabric to cover the flowers when they begin to droop and shed petals.

• Most sunflowers will produce more seeds if you attract bees to your garden to pollinate the flowers.

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