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Knotweed Lifecycle


The old stems may take up to 3 years to decompose, restricting growth of native plants due to stockpiled material. The underground rhizomes are thick and woody and when broken reveal a bright orange centre. They can extend to 2m in depth and 7m from the parent plant.


Preparation of new shoots, getting closer to the surface, ready for quick growth in Spring months.


A small amount of growth can begin in the month of March. As temperatures get warmer the nutrients will be drawn from the previously dormant rhizome system.


JK shoots start to make an appearance, breaking the surface with their spear-like shape and red/purple colour. New shoots rapidly grow due to stored up nutrients in the underground rhizome system. Growth rates of up to 4cm a day.


JK shoots have grown in size and developed from red to a more asparagus looking plant. Purple speckling will appear on the stem. They produce branches from nodes with shovel-shaped green leaves. There is increased activity with rhizome growth.


The canes develop quickly, moving appearance from asparagus to bamboo. The hollow, green canes produce branches from nodes, leaves unroll into a heart shape which are green in colour.


Canes can reach 2- 3 metres in height. Plants have dense clusters of stems with a lot of foliage. Leaves and stems have developed a zig-zag pattern. The leaves of the mature plant are up to 120mm in length with a flattened base and pointed tip.


Plant reaching its full growth. Creamy white flowers form towards the end of the month and hang in clusters from the leaf axils.


The clustered flowers are present to maximise pollination and potential for reproduction. Although seeds are produced they rarely survive.


Leaves start to discolour, turning from green to yellow and gradually wilting. The plant will start dormancy phase, whereby nutrients begin to be translocate down within the rhizome system.


Leaves have dropped off the plant, leaving orange/brown wood-like canes standing. Plants enter dormant stage.


Colour of canes turn deeper brown/maroon as they are subject to harsh weather conditions. Canes can topple over due to strong winds or snowfall. Stem and leaf material decomposes slowly leaving a deep layer of plant litter.