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‘Flore Pleno’ Perennial Sunflower (Helianthus multiflorus ‘Flore Pleno’)
A surprising find, ‘Flore Pleno’ is a full, yellow, perennial sunflower that lasts super long in the vase—at least two weeks. I don’t know why it’s not in nurseries, but it’s okay with me if we keep it as our little secret. It’s so nice to have a few flowers that are nice and easy to grow, yet no one else knows about them!
Pollinators like it, too.
The flowers resemble chrysanthemums and are up to 4” wide with long sturdy stems. They bloom by the fourth of July where I am in the northern Sierras of California. I once had a bouquet made with them that ran out of water, and I saw no wilting at all.
Keep them deadheaded for continuous flowering. But at the end of the season, letting the last flowers go to seed will attract birds, especially goldfinches.
This perennial sunflower gets 4-6ft. tall. It makes a nice summer hedge with big yellow flowers. It’s an herbaceous perennial.
It’s good in a perennial flower bed, but not deer resistant.
Growing the plants
These require full sun, or you’ll get powdery mildew. Remember that full sun means 6 or more hours of direct sun.
I give mine average water, not real dry conditions but I let them dry out well between watering sessions. For my location and soil I water once every one to two weeks, depending on temperature.
Start these as plants, they’re not available as seeds because they’ll be a genetic toss-up and you won’t know what the flowers would be like (see plant genetics). But they do form a clump that can be divided every few years.
If you’re a good propagator you’ll be able to start plants each year from small rhizomatous shoots. Or wait until there’s a larger clump and divide bigger sections.
Cut and treat these the usual way. The stems are long and should be cut down to a node for good side flowers.
There are other perennial sunflowers but this variety is unique on its own and excellent quality.
How many plants
How many depends on what you want them for and how much space you have. If you start with just one, you can keep propagating them by dividing or breaking off the root shoots. But it will take a few years.