Fences, hot wire, and spray repellents work for the animal types.
But you can bet if a human thief was taking what belonged to me or mine, it wouldn't be a trowel I'd be facing them down with.
I don't know that I'd risk life & limb for flowers - but let someone threaten family or the animals and I have NO problem pulling out the shotgun (after calling 911 - of course... yes.. that would be the proper order or things.. call the cops FIRST then start shooting holes .....)
If it was a spur of the moment attempt to steal his flowers, he did just fine (in England). If it was an ordered floral theft, we would have been hearing about the much beloved gardener who died defending his flowers (especially in the U. S.).
I certainly would have called the police and taken photos of the truck and thieves, but I doubt I would have done more to confront them. Things are just things. Even my animals would probably not earn the status of having me turn gun-slinger in a normal situation.
If my family were in danger, or the social situation put my family's food supply at risk, you bet I'd be toting a loaded assistant to get the thieves gone.