Alan Titchmarsh has said it is a "sin" that parks have been allowed to lose funding.
In the past two years, cuts have led to the loss of hundreds of experienced staff and more recently tipped parks charity GreenSpace into administration.
On the parks cash crisis caused by massive cuts in funding to local government, he said: "The sin for me is it's a great oversight that people don't realise that parks and open spaces contribute to the three main things that the Government is concerned with - education, law and order and health. Open spaces and the outdoors impinge on all three.
"If you're out in the open air, it's fresh and it's healthy. Education is learning about things that grow. On law and order, you can let off steam and you're less lightly to offend. I'm not saying it's the cure for all ills but it's a very important part of society. In areas without parks and open spaces, you get problems.
"The Government is a part of it. It's also the population in general, who I think need to be of a stronger voice when it comes to fighting for their parks. But yes, I do think that Government should realise what an important role parks play in people's lives.
"The problem is it's not always highly visible. It's one of those invisible assets - the spiritual uplift you get out of parks and open spaces - and we're not just talking about a sheet of grass. It's everything from bedding, trees and shrubs to a feel-good factor. It's somewhere for everyone because not everyone has a garden and the public spaces are the communal gardens of our country.
"You and I know the value of what goes on out there and this is something that people in flats can use. Its so important to talk about the spiritual sense of well-being."
- Horticulture Week's campaign, Make Parks a Priority, is calling for a parliamentary inquiry into the parks funding crisis. For information on how to lobby your MP to back Early Day Motion 219 which calls for an inquiry, click here.
Call to gardeners - Spread 'spiritual uplift' to attract young people
Alan Titchmarsh said gardeners should be "evangelical" in spreading the "spiritual uplift" of the pastime to try and divert young people from their obsession with celebrities.
Speaking at the Gardening Against the Odds awards, he said that even his new deal as the face of supermarket Waitrose is "missionary work".
He added: "Next year, I celebrate 50 years as a professional gardener. I can't believe it was that long ago. This is reality. We gardeners don't give up. Our gardening roots us in reality."
The award winners included Sajeda Kadir, who turned a disused playground in Camden into a community vegetable garden - nominated by Groundwork London. St Mungo's Putting Down Roots was a runner-up for its garden at St John's Church in Waterloo.