Japanese knotweed
Gives abundant nectar in late summer and autumn, but is a highly damaging invasive in Europe; never plant it, only use existing stands.
- Nectar
- Good
- Pollen
- Low
- Flowering
- JanFebMarAprMayJunJulAugSepOctNovDec
- Height
- 1-3 m
- Life cycle
- Perennial
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Japanese knotweed secretes abundant nectar in late summer, when other sources are exhausted, and is worked very heavily by bees. Most plants in Europe come from a single male-sterile female clone, so its pollen contribution is low; its value lies almost entirely in nectar.
Flowering
It flowers from late August to October in creamy-white racemes arising from the leaf axils. Flowering lasts 3-5 weeks and can provide an important late flow for winter stores.
Honey and pollen
In North America it is sold as a single-flower honey; it is dark amber with a mild taste reminiscent of molasses.
Note for the beekeeper
Invasive: it spreads by shoots from its roots and damages buildings, roads and stream banks; in many countries causing it to spread is prohibited by law. It must never be planted, and pieces of stem or root must not be moved. Using the late flow from existing stands is enough.