He singled out Bradford Council's decision to slash the district's floral displays by 80 per cent and shut the council's plant nursery.
Titchmarsh said: "I have sympathy with local authorities who have to work within tight budgetary constraints but when the soft target of floral displays is attacked, I see a direct link to those three local authority priorities: health, education and law and order.
"Without green spaces and flowers depression sets in, frustration can lead to crime and lack of growing things results in a lack of understanding of our responsibility for the landscape and inability to empathise with the way it works.
"This apparent frippery – the flowerbed – does more good to heart and soul than it is ever given credit for.
"All of which points up the fact that horticulture needs a robust champion in the form of the RHS which will, quite literally, put its money where its mouth is and get out to bring horticulture, gardens and gardening to the British population."
He added: "Statistics say there are 27 million gardeners in the UK, of a total population of 64.6 million- so there are 34 million of us who aren’t gardening.
It’s not all doom and gloom, 27 million gardeners is a powerful green-fingered formidable force, armed with spades, forks and bulbs, we can all play a part in growing for a better Britain."
Titchmarsh also took aim at TV controllers, calling them "whimsical" for not commissioning gardening programmes, backing up Carol Klein, who stated last month in HW that little gardening TV had been commissioned for 2016.