But Blackmore said he expected admission to the garden to remain free of charge despite reports suggesting the contrary. He added that funding for scientific research remained the top priority.
Britain's second oldest botanic garden receives an £8.8m grant from the Scottish Government, making up 74 per cent of its funding. Cuts could total £2m.
Blackmore said: "I don't expect there to be an admission charge. It's up to Scottish ministers to decide on admission fees and I know they have always preferred to have 'access free for all'."
He said RBG Edinburgh could cut opening hours by a maximum of an hour a day. "We would perhaps shorten the longer days in the summer when our overtime costs are quite high."
He added: "We really think the most important thing to protect is the fact that we are really one of the world's leading scientific botanic gardens and that's something we think would be very difficult to build back up.
"Where we would reduce our activities would be in relation to parts of the programme that we could build back up."
He said that green spaces were important to people during difficult times: "I recently visited New York Botanic Gardens and they said that they saw a huge increase in people visiting the gardens following 9/11. If more and more people are going to find themselves in challenging times, I think botanic gardens are part of the solution."
EXTERNAL SITES FACE UNCERTAINTY
RBG Edinburgh's three external garden sites - Benmore in Argyll, Dawyck in the Borders and Logan in Dumfries and Galloway - currently charge £5 admission and could be among the first hit following funding cuts.
Responding to the situation, Blackmore said: "They are superb gardens and very important to the local communities, but in terms of scientific research and focus, the emphasis would be on protecting Edinburgh."