Brian Jervis Ask a master gardener
I have always loved sunflowers but have never grown any. Anything I should know first? — AR
Sunflowers are a great addition to any garden. Birds will love them and they can serve as a food source for both animals and humans.
The flower head of sunflowers is actually a cluster of hundreds of tiny flowers that we call florets. Sunflower seeds are individual fruits that form on the sunflower’s head, and the large yellow petals surrounding the flower head are colorful protective leaves.
While it’s logical to assume that the sunflower gets its name from the bright yellow leaves of the stereotypical sunflower, it was more commonly called sunflower because the flower head follows the sun during the day. This tracking allows the plant to absorb as much sunlight as possible through a process called heliotropism.
We’ve had a cool spring but now would be a good time to plant sunflower seeds as they prefer soil temperatures of at least 60 degrees for germination. For best results you need a location with full sun.
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Plant your sunflower seeds about 6 inches apart at a depth of 1 to 2 inches. Depending on which ones germinate, thin them out to about one plant every 12 to 15 inches. If planting lots of sunflowers in rows, leave 2 to 3 feet between rows. Sunflowers are not high maintenance, but you do need to water them.
There are a few insects that might find your sunflowers palatable, such as leaf-foot bugs, stink bugs, or aphids. For this reason, sunflowers are often grown as a “fall plant” to lure unwanted insects away from vegetables in your garden. Sunflowers also serve as a magnet for beneficial insects.
Sunflowers can occasionally show symptoms of powdery mildew or rust, but if your plants are healthy, they will likely thrive. If not, you can apply copper fungicides or neem oil. Be sure to test the neem oil on a small area first, as heat combined with horticultural oils can damage plants.
If you’re growing your sunflowers with the intention of eating the seeds, you can expect to ripen in early fall. You will start to see signs of maturity when the back of the flower head turns from green to more of a yellowish brown. The flower head also starts pointing towards the ground. When this happens, you will find that the tiny flowers have dried and fallen out, exposing the mature seeds.
To harvest these seeds, cut off the seed heads, leaving about 30cm of stalk, then hang them in a well-ventilated, warm, and dry place for several weeks. When properly dried, you can rub the seeds with your hands or brush flower seed heads together to release the seeds.
Most of us think of sunflowers as yellow, but there are many varieties ranging from yellow to orange to brownish-orange and just about everything in between. Much luck!
You can get answers to all of your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, stopping by our Diagnostic Center at 4116 E. 15th St., or emailing us at email@example.com .