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https://en.wikipedia.org/wiki/Comfrey
Comfrey should be harvested by using either
shears, a
sickle, or a
scythe to cut the plant about 2 inches above the ground, taking care handling it because the leaves and stems are covered in hairs that can irritate the skin. It is advisable to wear gloves when handling comfrey. Despite being sterile, Bocking 14 Russian Comfrey will steadily increase in size. It is therefore advisable to split it up every few years (and at the same time propagate more plants that can be shared with fellow gardeners!). It is however difficult to remove comfrey once established as it is very deep rooting, and any fragments left in the soil will regrow. Rotovation can be successful, but may take several seasons. The best way to eradicate comfrey is to very carefully dig it out, removing as much of the root as possible. This is best done in hot, dry summer weather, wherein the dry conditions will help to kill off any remaining root stumps.
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