Posted: 08/03/2015 at 14:16
Re taking seeds and cuttings in gardens open to the public - I spent a season many years ago as a volunteer in a local garden opened primarily for the water gardens and azalea / rhodie displays. I was often on 'escort' duty for group visits and we were asked to ensure that people did not damage the plants. The advice was to especially watch out for 'little old ladies with nail scissors taking cuttings'.
The thought was - if one person takes a cutting properly it will do no harm. If a thousand people visit over the course of a few days and they all take a cutting from the same plant & some do it badly - the plant will suffer. Much the same with gathering seeds really - especially annoying if it is a garden which relies on propagation and nursery sales for part of it's income.
I have always found that if you approach a gardener and ask if they would mind you taking a cutting or seed head - they will say yes. Gardeners are generally the most generous group of people I know