Back in October 2012 in my post “In Praise of Persicaria” I wrote about a couple of my favourite herbaceous plants of late summer and early autumn: Persicaria affinis and Persicaria amplexicaule. Now I must add a third to my list of favourites: Persicaria polymorpha.

Persicaria polymorpha in our back garden.

Persicaria polymorpha is a dramatic plant. Although it is as tall and statuesque as Japanese Knotweed, it is a well behaved plant and is generally reckoned not to have its relative’s invasive tendencies.

I was given my plant last June. It had been cut back and was just a root ball with some short shoots but I was given a photograph of the plant before it was cut back and I knew this was a plant I wanted to grow. The plant dies back in the winter and it wasn’t until late April or early May that sizeable shoots started to emerge. By the end of June the plant was around five feet (150 cm) tall and it started to flower in the middle of July. When mature, the plant should reach 6 feet (180 cm) tall, with a similar spread.

The flowers are a lovely white froth, hence the English name White Fleeceflower. The flowers fade to pinky bronze by September. It is far prettier than Japanese Knotweed.

I’m growing my specimen in the lawn in the semi-shade, as our soil is very light and I want the plant to have enough moisture. Finegardening.com reckons that the plant can tolerate some shade and drier conditions, though it prefers moist soil. In our garden, not many insects seem to like the flowers.

Persicaria polymorpha works well as a single specimen in a lawn or can be planted in a wild garden. If you have a large border it would be great at the back, perhaps with grasses such as Miscanthus, as a foil for shorter, colourful perennials. It doesn’t need staking but heavy rain will push the foliage down, increasing the plant’s spread, so allow for this. The plant can be divided in the spring.

If you’re in the United States, you may find the reviews on the Dave’s Garden website helpful.

Incidentally, I’m not the only person who loves Persicaria. Here is an excellent piece on the Ben’s Botanics blog.