Royal Botanic Gardens, Kew director Richard Deverell has said he is "not dismayed" that Kew faces a £5m funding gap and has balanced the books for 2014/15 - two-thirds by cost reduction and one-third by revenue growth.
He will ask for voluntary redundancies, reduced working hours, unpaid leave and compulsory redundancies. Some 125 of Kew's 750 staff could go. Back-office staff and scientific personnel will be worst hit.
Deverell said he will "protect" horticulture in the face of the 12 per cent operating income gap, while improved standards of horticulture and more events could lead to a doubling of visitor numbers to two million by 2020.
"It's credible by 2020 to have two million visitors," he added. "We need to give people many more reasons to visit through stronger events and festivals, higher standards of horticulture and better scientific interpretation. I'm entirely confident we can get through this cost/headcount reduction and do a lot to grow income."
Kew will give details before this summer of reviews into making horticulture better, merging the three science departments and how the education department will work in the future.
Deverell admitted: "We may have to reduce scope and stop doing some things but we will protect public experience here and at Wakehurst Place. I'm seeking to protect the horticulture teams at Kew as much as possible."
Horticulture brings in £12m at Kew and has been more "squeezed" than science in the past five years, he added. Defra funding is down £1.5m for 2014/15 and Deverell said he "needs to get the department to recognise the value of what Kew does".
Kew has pegged entrance charges at £14.50 for a third year. Deverell said they have risen too rapidly. Kew, which has an operating income of £40m per year, could generate more income through scientific grants and philanthropic funding, he added.
Total incoming resources for 2012/13 were £59.8m (2011/12: £48.9m), of which £32.5m (£28.5m) was grant-in-aid from Defra. Total resources expended were £58.5m (£55.4m), leaving a surplus of £1.3m (deficit £6.5m). Grants and donations were £13.1m (£6.4m) and income from activities was £14.1m (£13.9m).
But expenditure on salaries (2012/13: £28.8m/2011/12: £25.4m), redundancies (£979,000/zero) and numbers of staff in information and support services (177/116) are rising. Science and horticulture staff numbers are 434 against 453 and overall staff number 758 compared with 714.
Union Prospect, which has 166 members at Kew, said this is the first time that science cuts have been looked at by Kew.
Visitor numbers in 2013 were 1.4 million, up from one million. In 2012/13, overall income from non-Defra sources was £22.4m compared with a £25.7m target, with admissions-related income of £4.5m against a £5.8m target and cash from Kew Enterprises at £1.2m against a £2.2m target. Grant and projects income was £16.2m against a £17.7m target.
Key support - Backing student programme and securing funding
Kew Guild president Bob Ivison said: "We want to help Richard through this because he is committed to horticulture. We as an industry ought to support him to the full."
Ivison said he hopes that the guild can support Kew through its "severe financial pressure" by supporting its student programme financially.
He added that Kew's capital funding is secure for rebuilding the Temperate House and the refurbishment of the Palm House, but the "area of difficulty is revenue funding".
On raising more cash, Ivison said: "I don't think there are any bad ideas, it's how you apply them. We'd want to be sure the skill base in the garden is not degraded. Kew has to look at the way things are done. More research grants have to come in, with the target being the pharmaceutical industry."