Weed or Knotweed? That is the Question!

Senior Gardener, Ollie, explains about some of our most hated weeds…

One of the most pressing jobs at this time of year for the gardener is weeding. As the days get longer and the soil and air temperatures rise, weed seeds start germinating and perennial weeds rear their ugly shoots again. There is however more to weeds than them being just a nuisance.

Would you believe that some of our most hated weeds arrived in our gardens as invited guests! Japanese Knotweed (Fallopia japonica)is probably the most regrettable.

Japanese Knotweed

It is a feared herbaceous perennial weed, which roots very deeply and strongly. It has extremely vigorous, powerful stems that are capable of pushing up through tarmac and that will grow to over 7 feet high in one growing season.

It was originally introduced to Britain from Japan in 1825 as an ornamental plant, grown for its handsome red-flecked stems and large heart shaped foliage. Gardeners of the time didn’t realize how invasive it was and how easily it propagated form tiny fragments. This has led to its spread and the problems it now poses today.

Another surprising introduction to the British Isles is Ground elder (Aegopodium podograria). Unlike Japanese Knotweed, Ground Elder is thought to have been brought to the British Isles as a food crop by the Romans. The young leaves were eaten in salads and as it grew and spread easily, it was a reliable crop.

Ground Elder

There are many examples of edible “weeds” or should I say native wildflowers all around us. An easily recognisable example is the Dandelion (Taraxacum officinale). The leaves can be eaten raw or cooked (Less bitter when young), the dried root is used to flavour drinks such as dandelion and burdock and wine can be made from the petals.


Although collecting plants to eat from the wild is incredibly satisfying, please don’t collect any wildflowers if you are unsure of what they are or if they are a protected species.

If you are looking for a good way to eradicate pernicious weeds from your garden then persistence is the key. I know it is hard work, but digging weeds out is effective if done systematically. Use a fork instead of a spade to avoid chopping roots up into many fragments, which will regrow.

After digging, when any weed fragments have grown back, use a systemic herbicide to finish them off. Sounds strange, but the most effective time to spray is when the weeds are in full growth and healthy. Carefully follow the instructions and spray as much of the leaf area as possible. Weed-wipe gels are a great way to apply chemical precisely and avoid hitting your wanted plants.

Happy Weeding!