The number of visitors to Wakehurst Place has dropped drastically since the gardens introduced car parking charges last year.
But the Ardingly estate insists the change is part of a financial model to safeguard it for the future.
From the introduction of the charges last April until March this year, Wakehurst welcomed 164,417 visitors.
In the same period in 2013-14, there were 314,836 visitors, a drop of 48 per cent.
Mike Joyce said the change is ‘targeting just National Trust members’.
He said the amount of money taken does not justify the loss of visitors as ‘they are nowhere near the targets set’.
This is an organisation that has taken a financial hit, but that it’s also an organisation that is taking measures to improve and recover its financial outlook
Parking charges at Wakehurst are £2, £5 or £10. From 1 April 2014 – 31 January 2015, it took in £85,334 with the charge.
Wakehurst embarked on a new car parking policy after revealing a £1.4m to £1.6m deficit in its running cost, caused by 80 to 85 per cent of its 400,000 annual visitors being National Trust members who enter for free.
A spokesperson for the Royal Botanic Gardens, Kew, owner of the gardens, said: “2014 was a transitional year for Wakehurst Place and we had anticipated this drop in day visitor numbers. What is heartening however, is the 225% growth we have seen in season ticket sales.”
Until the car parking fee introduction, Wakehurst was on an upward trend. In 2013 the gardens had 326,134 visitors, up to 350,839 in 2014.
The spokesman added: “We have to establish a viable financial model to safeguard Wakehurst for future generations, and with further investment in the visitor experience and exciting plans in place for 2015 – including celebrations for our 50th anniversary – we will grow and attract new visitors to Wakehurst.”
But some National Trust members say their membership entitles them to visit the gardens for free.
Ray Turner said: “It looks to me as if Wakehurst is in a right mess. I’ve stopped going as much as I did last year.
“I already have my National Trust pass which entitles me to free entry. I’m not paying to park in a car park which is on land owned by the trust. Sorry Wakehurst but the owner of the property is the National Trust not yourself.”
A petition to remove parking charges at Wakehurst Place has been signed by 1,830.
Mike added: “Wakehurst in 2009 was getting 440k visitors, in 2013/14 it was the 6th most visited National Trust property.
“Why are things being allowed to continue?”
Wakehurst’s visitor entry revenue from the introduction of parking charges until March this year saw the garden take in £645,606, up from £326,802 the previous year.
But retail revenue fell from £770,559 to £407,970.
But Wakehurst does take in additional revenue from commercial assets.
A spokesman explained: “What the figures show you is that this is an organisation that has taken a financial hit, but that it’s also an organisation that is taking measures to improve and recover its financial outlook.
“The new charging model allows Kew to directly link its income to the number of visitors. This, in turn, will enable us to invest in the long-term future of the landscape and visitor offer.”