Saturday, June 14, 2014

Persicaria polymorpha

Now that's a mouth full of Latin, isn't it?  I believe that you'll find that if you say it fast three times, Persicaria polymorpha is easier, however, than repeating "giant fleeceflower" quickly three times.  This beast of a plant lives in my front landscaping, near the walkway, and it always causes a scene when a visiting gardener sees it in flower.

I discovered it myself several years ago while on a gardening tour in the neighboring county where it was shining brightly and stealing the show at a friend's garden.  I immediately left the tour and proceeded to my then-favorite garden center to ask if she had any.  Thankfully, she had one small plant left over from a custom order for a landscape job and I took it home and planted into a nice spot.  One thing to admire about Persicaria;  a small plant will flower and one year later it will be spectacular!


I called my giant fleeceflower a beast, but, other than its size, it is an impeccably well-restrained garden citizen.  Actually a strain of knotweed, Persicaria polymorpha might flop on some more diminutive neighbors after a heavy rain, but it will soon stand itself back up (mostly) as it dries.  It helps if you don't ever fertilize giant fleeceflower, starving its growth to stay within the constraints of its genes.  It doesn't spread by runners or self-seed, as far as I can determine.  I've recently divided my now 5 foot diameter clump to start others in my garden and it is as simple as dividing a daylily.  Well, perhaps similar to dividing a slightly tough-rooted daylily.    I'd certainly recommend putting it among shrubs or perennials.  Standing alone in a lawn, Persicaria will just look like a big weed you should have removed.


Persicaria polymorpha was formerly known as Polygonum polymorphum.  Because of its good behavior, some speculate that it is a hybrid, rather than a species.  It grows about 5 foot tall, takes all the drought and sun you can throw at it, and is hardy in the worst of my Zone 5 winters.  A perennial, all the care that giant fleeceflower needs is to cut it to the ground each spring.  No pests seem to bother it, it blooms all summer long from early June through mid-September, and those creamy white panicles don't brown and enter an ugly phase.  Even in my hot Kansas sun, I might call them a little "toasted", but they primarily stay creamy for a long time and then turn reddish-brown in fall.  I leave them on all winter to provide some structure in the snows.



4 comments:

  1. Greetings, Love your blog!
    I am planting some persicaria polymorphas and like you, I actually want to place it in my foundation garden. (I don't see many people doing this on the blogs, but I'm going to give it a try.) My yard is viewed from a highway, so I think it will give some strong impact and take up lots of space, which is what I need right now.
    Now that you have years of experience, just wondering how far from the foundation would be smart?
    I am going to put 2-3 right under a high window where I want a WOW effect.
    I have plenty of space but not sure how much room to give them from the foundation, and then how much room to give in front of them.
    I am planting 2 gallon pots, with huge multiple roots. Full sun, facing south.
    Finally, can you tell me what you do during the growing season in terms of any trimming, cutting back needs, after a storm, etc?

    Thank you in advance for your help!
    Mary in Wisconsin

    ReplyDelete
    Replies
    1. Mary, I would place it at least 3-4 feet from a foundation. And 4 feet from anything else; they'll really take over a large spot in a few years.

      They've gone through most weather without incident, although there have been one or two storms which flatten the edges and drape them over anything around them where I've had to cut them back. I haven't experimented with "cropping" them at around the 2 or 3 foot stage to see if it will ultimately lessen their height without affecting the bloom, or at least strengthen the stems for the storms. For the most part, I simply trim them to the ground before each growing season and keep other plants away from the Persicaria, which will smother smaller plants in their way.

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  2. Hi. I wanted to find out if I should cut down all those brown flowers. It’s not so pretty anymore. I can’t find answers anywhere. And they have seeds on them. Don’t want to have the flower to spread anymore then it is now. Appreciate the answer.

    ReplyDelete
    Replies
    1. Hi. You can certainly cut the flowers off anytime. I would leave the foliage on so the plant stores food. I haven't cut off the seedheads on mine and while it spreads like wildfire from the roots, I haven't seen it spread by seed, for what it's worth.

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