This was the message from speakers at the Professional Gardeners' Guild specialist gardens seminar Historic Gardens Under Threat as they discussed the impacts of the Sustainable Use of Pesticides Directive 2009.
University of Sheffield animal and plant science senior research fellow and honorary lecturer Ken Thompson said: "We haven't tried hard enough to educate visitors not to expect plants to look as though they are made of plastic because some plant damage is not only inevitable but actually desirable."
He added: "We should educate them about what gardens should actually look like - living, breathing things with lots of animals in them. Visitors need to be told how important gardens are for biodiversity."
Fargro integrated pest management consultant Neil Helyer said there were numerous biological controls at gardeners' disposal that could be used outside and under glass. But English Heritage head of gardens John Watkins warned that there would still be many challenges to historic gardens.
"Managing paths is going to be a major problem for us," he forecast. "Flame throwers are an option but I don't like it because of the use of fossil fuels. Oak processionary moth is increasing and we will need pesticides to help us deal with this. Horse chestnut bleeding canker is also starting to give us problems."
The changing climate is also affecting plants' ability to enter proper dormancy, Watkins warned. This could cause problems by making them more vulnerable to pests and diseases, he added.