Growing Persicaria (Bisort, Knotweed)
Latin Name Pronunciation: per-si-kar'-ee-ah
Members of this genus are sometimes included in Polygonum (known to many gardeners through the unwelcome guest called Knotweed). Upwards of 50 species of annuals and perennials grow in a range of conditions worldwide. The ornamental, noninvasive species add carefree late summer color and range in size from low mats suitable for rock gardens to tall, back-of-the border specimens.
Light/Watering: Full sun or partial shade; moist soil is needed for good flowering.
Fertilizer/Soil and pH: Any moist soil is acceptable. We do not recommend fertilizing at planting time or during the first growing season.
Pests/Diseases: Usually trouble-free; slugs may be a problem.
Dividing/Transplanting: Divide large clumps in spring; plant crowns at soil level.
End-of-Season Care: Cut down and remove top growth. After the ground freezes, protect plants during their first winter with a 4-6in layer of oak leaves, pine boughs, or straw.
Calendar of Care -- Persicaria
Early Spring: Gradually remove winter cover.
Fall: Cut back to remove spent flower heads.