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We want to cover a North-facing fence 10m wide by 2m height with clematis and are considering Grandiflora. Would you advise having two (or more) plants or would one in the centre be enough if we train it horizontally? How long would it take to get good coverage of the fence? Thank you.

Hi the growth rate that you could expect would be around 3-4 metres per year, so I would say at least 2 plants and total coverage should be achieved in 2/3 years
Hope this helps

Clematis – Montana

Chris and Suzy