The giant fleeceflower (Persicaria polymorpha) is a massive perennial fairly new to the market. It forms a clump so dense that no weed can penetrate it, so it really holds its own in the garden. Its very thick stems are hollow and bamboolike, but its large oval leaves look nothing like the narrow lance-shaped leaves of most bamboos and the two plants are not related. The giant fleece flower blooms all summer, for about 3 months starting in May or June depending on your climate, with large panicles of feathery creamy white flowers. From a distance it looks like a goat’s beard (Aruncus dioicus), but its foliage is very different. By September, blooming will be in decline and the flowers will have taken on a pinkish hue. There is no winter interest and it’s best to cut it back to the ground in late fall.
The flowers of the giant fleeceflower are scented, but their perfume is certainly not flowery. Some people like the smell, others hate it! Fortunately you have to be really close to notice it.
Giant fleeceflower readily reaches 4 feet high by 4 feet in diameter (1.2 m x 1.2 m) in its first year and can eventually reach 8 feet (2.5 m) under good conditions, so it is truly a huge perennial. It tolerates pretty much any kind of soil, but does best rich, fairly moist soil. Well-established plants are fully drought resistant. Flowering is more abundant in sun or partial shade, but it will grow well and flower modestly in the shade. It adapts to most climates, from hardiness zones 3 to 9.
Unlike other knotweeds (genera Persicaria, Polygonum and Fallopia), many of which are highly invasive, giant fleeceflower is not rhizomatous but grows in dense clumps. After several years of culture, however, it may produce an offset or two. Dig them up while they are still young to stop any unwanted expansion. You can use these offsets for propagation purposes, but it is also possible to multiply this plant by cuttings or by division. There appears to be no seed formation on cultivated plants, so no threat it can spread by seed.
Finally, an additional tip: plant lots of spring bulbs at the base of your giant fleeceflower. It’s slow to come up in the spring, so the bulb will have time to flower and begin to turn yellow before big guy’s leaves hide them from view. So you will have lots of flowers in spring and blooms all summer until fall: truly a winning combination!
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I’m considering this plant in beds on either side of the porch entrance. Can they be trimmed to stay at a certain height/width? Will they overwhelm the entry walkway!
I used the hollow stems to make a bee house this year, i don’t know if it will work as did it too late in the season. I have mason and leaf cutter bees in my yard so I’ll try in early spring.
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Do _not_ cut in autumn, wait until late spring, when new stems are showing. Because lots of small wildlife will use the hollow stems to survive winter.
I never thought of that. I just let the stems remain where they fall, so that should be fine for wildlife, but everyone doesn’t let nature take its course.
Hi my fleece flower was beautiful and white and after lots of rain it turn brown. Should I cut flowers off or it will still bloom white. I can’t find any answers anywhere. Thank you
There should be more flowers coming, but mixed in with the brown ones. If you trim them off, that’s all for the year.
Hi, Please, Please, please. Can anyone tell me how to actually propagate a Giant Fleece flower?
Do you dig up a shoot? How deep, how much of a root? Take a cutting? I have tried all over the Internet and nobody gives precise instructions. Just saying propagate in Spring or Fall.I really would like to have more of this delightful plant.
You can dig up and divide, preferably in early spring or in fall. Or take stem cuttings (removing any flowers). I think if no one is giving any specific information, it’s because it’s just basic plant multiplication. There’s nothing special about multiplying this plant.
One of my fleece flowers got cut down accidentally by my neighbor last year. It’s not coming up this year so far while my others are coming along pretty well. Does that mean it has died? I don’t see anything
Give it time. It’s a bit slow in spring.
Could this be placed near a septic tank? Are the roots likely to damage pipes?
This is an exceptionally deep-rooted perennial and it’s best not to grow above a septic tank. It can be grown next to one, though.
Is it safe to move this plant with success in not killing it? Does it have a long taproot? What do I need to know about this process? Thank you.
It’s easy to move, even though the roots (sort like a carrot, but densely surrounded by secondary roots) are a bit fragile. I’d do it in the fall, if possible, or early in the spring.
Hello, i just planted this plant about a month ago. It really hasn’t grown much yet and before i planted it a lot of the leaves started to shrivel and turn red. I ended up plucking them as they looked mostly dead. Should it have grown a little by now or do i just need to be more patient?
It may be suffering from transplant shock. If you, just let it be, watering if needed. If so, it might not grow much at all this year, but will hopefully recover the next.
Hi I have had my giant fleece flower for several years and it never fails tio impress. (ZONE 2B). I have noticed today that one or two leaves are half deep green and half yellow, right down the middle. (Only a few on one side)
We have had a couple if weeks of intense heat and moisture. Could this be the cause?
Any help would be appreviated , it is my pride and joy.
If the leaves are all on the same stem, it’s probably a mutation called variegation. It happens fairly often: enough that most gardeners will probably run into one in their own gardening. If it’s a leaf here and there… well, in that case, I really couldn’t say. It’s certainly nothing very serious.
Hi! I live in Michigan and I recently discovered these amazing plants! Do you know where I can find them? Maybe certain website you trust? Also I am wondering when the best time to plant them would be?
Thanks for your time!
Actually, they’re quite widely available. Here’s a mail-order source you could try: https://www.forestfarm.com. Best time to plant? From spring through fall, but early spring and mid-fall are best.
I have 3 of this plant that will go into very large containers due to the fact that I don’t believe they will survive among the roots of a silver maple. There will be enough sun, contrary to what one might think. I plan to wrap the containers for overwintering (I live in Zone 5b). Do you think I’m missing something here?
No. To me, this sounds like a great idea!
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