Glyphosate is currently undergoing EU renewal. Head called on the RHS to lead research into glyphosate's impact on gardens.
He said: "Any ban would have a colossal impact on agriculture as well as horticulture. What we want to do is encourage gardeners to make the best for wildlife. Glyphosate is the least of our problems. It's a lot less damaging than double digging and destruction soil when clearing a bed."
He added: "As long as glyphosate is used properly when there is a problem there is very little serious evidence of impact."
He said using biocides as directed by the label and their impact on garden wildlife-is "top priority" for research and that could be funded by the RHS and its Plants for Bugs project. That will be discussed at the forum's 17 November meeting at the Natural History Museum, marking 10 years of the organisation.
Head said neonicotinoids are different and should be banned. Bayer have replaced Thiacloprid, a neonicotinoid, with Deltamethrin, a pyrethroid, in Provado Ultimate Bug Killer. But Scotts Bug Clear incorporating the neonicotinoid acetamiprid is still on sale. Buglife chief executive Matt Shardlow said: "Clearly, Buglife would rather there were no powerful insecticides used in gardens, or only in extremis."
But Head said: "Glyphosate is a lot lower down my agenda partly because I use it when I have to. I prefer not to use anything but if you have ground elder among perennials you have no option. That's my view, other people will see it differently."
Monsanto UK business director Gary Philpotts said: "There is a wealth of data available to regulatory authorities around the world dating back more than 40 years. This data is used to periodically evaluate Glyphosate suitability for approval.
"There are a number of studies prescribed by the authorities to ensure that substances do not pose any unacceptable risks to human health the environment and wildlife. The required studies are conducted with representative species of various forms of wildlife, including insects, earthworms, birds and mammals.
"Science-based evaluations conducted by regulatory bodies and other scientific institutions have concluded that typical glyphosate usage does not pose any unreasonable risks to wildlife when used according to label directions.
"Glyphosate is readily degraded by soil microbes and therefore, generally dissipates rapidly from garden environments.
"Of course helping gardeners to use and dispose of garden chemicals safely is a priority for the industry and several communication initiatives with RSPB. RHS and the British Bee Keepers Association are ensuring that the impact of these helpful products keep risks to a minimum."