In the cool darkness of a summer morning, I stared in wonder at the bright faces looking back at me. My young sunflower (Helianthus annuus) grove was standing like soldiers waiting to salute the rising sun.
During the previous day their leaves and flowers tracked the sun as it made its daily voyage from east to west across the sky. And now under the cover of nightfall they rotated their stems back to greet the sun again through a process called heliotropism.
New research on the subject has found that solar tracking is caused by different sides of the plant’s stem elongating at alternate rates throughout the day and night. In order to track the sun’s movements during the day the growth rates on the east side of the stem are higher while the increased growth rates at night on west side allow sunflower stocks to turn and greet the dawn. This daily elongation maximizes growth and is why sunflowers planted from tiny seeds in spring can reach over 10’ tall by summer’s end! Once the plants mature, sunflowers will predominantly face east so that the warming sun will heat the flowers which is thought to better attract pollinators.
As sunflowers grow and mature a whole community of organisms emerges high above the ground. Take a moment each day to observe all the lives that are carried out on sunflowers. Turn over the leaves and you will discover multiple species of aphids, ants and lady bugs. Peer into the crevices of the flowers and you will happen upon goldenrod crab spiders. These fascinating creatures camouflage themselves by changing their body color to yellow or white depending on the species of plants they are living on! Once disguised among the pedals they prey upon unsuspecting bees or wasps. At the same time, daddy long leg spiders and earwigs seem to wait patiently to feed on insects and plant juices while leaf miners make iridescent tunnels through sunflower leaves. As the flowers open, honey bees comb the pollen laden florets gathering the golden powder on their hind legs before journeying home to their hive.
In autumn, as sunflower seeds ripen and their leaves brown along the stem, the heavy flower heads droop looking to the ground as if deciding where to plant their seeds to start the cycle again next year. The drooping, though, is no match for the most agile song birds like goldfinches, house sparrows, and warblers who pick away at nature’s most natural bird feeders.
Oh to behold the power of the sunflower and its happy place in our gardens!
To bring the power of the sunflower to your garden, here are some of our favorite heirloom varieties to try:
Tarahumara White Seeded
Hopi Black Dye