Giant Fleece Flower Plant Profile (Persicaria polymorpha)

Giant Fleece Flower (Persicaria polymorpha)

Marie Iannotti 

Also known as white fleece flower and white dragon, giant fleece flower looks like a shrub but it grows like a herbaceous perennial, dying back to the ground in winter. However, it makes up for it by quickly growing upwards of five feet tall and almost as wide the following season. The giant fleece flower stays in a well-behaved clump and rarely seeds or spreads by rhizomes. It is widely adaptable and requires little maintenance.

Giant fleece flowers have dark green, alternate pointed leaves with slightly serrated edges. The stems are sturdy but may need some support by the end of summer. Its astilbe-like white plumes are popular with butterflies and even the late-season seed heads are also attractive.

Botanical Name Persicaria polymorpha
Common Name Giant fleece flower
Plant Type Herbaceous perennial
Mature Size 3 to 5 feet tall with up to 4 feet of spread
Sun Exposure Full sun
Soil Type Moist well-drained soil
Soil pH No preference
Bloom Time Summer
Flower Color White
Hardiness Zones 4–9
Native Area China, Japan

How to Grow Giant Fleece Flower Plants

Giant fleece flower is generally grown from divisions, so you probably will not find seed for sale. Plants can be hard to find in nurseries, but it never hurts to ask. You may have the best luck by asking around local gardening groups and seeing if one of your fellow gardeners will give you some of theirs. The young plants don’t look like much, but a small clump will quickly fill out and blossom.

It can take a year or two for giant fleece flower plants to reach their mature size, but once they do, expect a bushy plant with exceptional height and spread. It will bend slightly toward the sun, but should not need staking. The flowers start in early summer and peak shortly after. No regular deadheading is required to keep it blooming. As the plumes age, they will turn a pinkish mauve and eventually develop seedheads.

Because of its size, giant fleece flower will make a statement anywhere in the garden, but its white plumes make it especially useful for a partial shade garden. It’s great for any border that needs a vertical accent and it also works well to plant several together as a screen or to block a view of something like an air conditioning unit. Just be sure to give your plants plenty of room, as they will fill out quickly.

Light

You can grow giant fleece flower in full sun to partial shade, but you'll get the best flowering if the plants get at least five or six hours of sun per day. Too much shade can make this very tall and top-heavy plant floppy.

Soil

Giant fleece flower is easy to grow and widely adaptable, although it's happiest in moist, well-draining soil. It can tolerate dry periods and is not particular about soil pH.

Water

The giant fleece flower has average water needs and will adapt to most soils. Although it enjoys moisture, it does not like to sit in wet soil.

Temperature and Humidity

Giant fleece flower is a reliably hardy perennial in USDA hardiness zones 5 to 9. It's tolerant of heat, humidity, and moderately tolerant of drought once it has been established in a garden.

Fertilizer

Fertilizing isn't necessary; in fact, it can decrease the blooms.

Pruning

Giant fleece flower plants require very little maintenance. Cut back the old, dead foliage in early spring, before new growth starts. The thick stems are hollow and cut easily. You could probably prune it back after the end of summer if you prefer, but it looks so good in the fall that you may want to keep it standing. If you want a shorter, bushier plant that blooms later in the season, you can shear the entire plant in late spring, as you would with other fall bloomers such as asters.

Propagating the Giant Fleece Flower

This plant can be propagated by division in spring or fall. Propagate by seed in spring.

Comparison of Like Plants

Persicaria polymorpha is sometimes confused with Polygonum cuspidatum or Japanese knotweed, which is considered an invasive plant. There is no research to suggest that Persicaria polymorpha should be grown with caution since it is a clump former and does not travel in the garden.