How To Grow Sunflowers To Beautify Your Garden and Decontaminate the Soil
With their vibrant yellow petals, set off by fuzzy brown centers, sunflowers easily steal the show in any garden or bouquet.
“Sunflowers have an uncanny ability to make you happy. Whether they’re bright yellow or burnt orange, they bring a sense of warmth and joy to a home,” says Alison Katz, a gardening expert for Ferry-Morse, a home gardening supply company.
Sunflowers also benefit the ecosystem of your backyard, by feeding pollinators like honeybees and bumblebees.
“The large heads of sunflowers offer a huge amount of nectar and pollen,” says Dave Thompson, general manager of Seeds of Change, a line of organic gardening products.
Sunflowers also help detox your soil, by absorbing caustic heavy metals, like lead and copper.
The National Garden Bureau designated 2021 the “Year of the Sunflower,” so this is as good a time as any to honor the colorful blooms by planting them around your home.
When to plant sunflower seeds
Katz recommends planting sunflower seeds in late spring, when the soil is warm and the spring frost has passed. The soil temperature should be a minimum of 60 degrees.
“Depending on the variety, sunflowers can take 75 to 90 days to bloom, which will give you beautiful, mature sunflowers in July and August,” says Katz.
“When looking for sunflower seeds, it’s important to plant ones that are free of neonicotinoids, an insecticide that can be present in pollen and nectar and make the sunflowers toxic to bees,” says Thompson.
Find the right spot
For a sunflowers to flourish in all their glory, these sun worshippers must be located in the right spot in your garden.
“Just as the name says, sunflowers are best grown in full sun. Ideally, they should receive six to eight hours of sunlight per day, so they’re best for summertime growing, when the days are longer,” says Thompson.
“While sunflowers aren’t extremely particular about the soil, they require a fair amount of nutrition, so you want to plant your seeds in rich, well-draining soil,” he adds. “If you need, a slow-release fertilizer may come in handy. For sunflowers, and all gardening, I also recommend checking the acidity of the soil. Sunflowers prefer 6.0-7.5 pH.”
Since sunflowers grow so large—some up to 12 feet tall—they tend to have fairly large root systems.
“A good-size plot is important to properly space the seeds and give the plants the space they need to thrive,” says Katz. “This can vary from 12 inches to 24 inches apart, depending on the sunflower variety.”
The recommended spacing should be noted on the back of your seed packet.
How to water sunflowers
Sunflowers need TLC to thrive, and need to be regularly watered.
“Once the sunflowers begin to sprout, reaching about 4 inches tall, they need lots of water around the root zone, which should still be near the surface of the ground. Once the plants start growing taller, water deeply but infrequently, about once per week, to complete saturation. This will encourage strong, deep root growth,” explains Katz.
Harvesting sunflower seeds
If you plan on harvesting and eating the seeds, be sure to plant the right variety of sunflower. Taller varieties, like Mammoth Russian, Kong Hybrid, and Sunzilla, should all produce a plentiful amount of seeds.
Just be sure to cover the sunflower heads with thin fabric like cheesecloth, to protect them from birds and other hungry critters. To harvest the seeds, you need to let the sunflowers die on their stalks.
“The petals should become dry and start to fall, and the head should turn brown. You should also be able to see that the seeds are plump and somewhat loose,” says Thompson.
After the sunflowers have died, cut the flower stalk about 12 to 18 inches from the head. If the flower is not completely dry, hang it upside down in a well-ventilated, warm, and dry spot. Once dry, brush your fingers lightly over the head, and the seeds should easily fall off.
There are a number of ways you can eat harvested sunflower seeds. Roast the seeds in the oven (with the kernel still inside), with a drizzle of your preferred oil and spices. You can also crack the shells and eat the kernels raw.