The Professional Gardeners Guild (PGG) has revealed that some head gardeners are earning as little as £16,000 a year, with most paid between £20,000 and £32,000.
The PGG has released salaries and rates guidelines and urged employers to improve pay and conditions. Chairman Tony Arnold said: "Lots of us work outside normal health and safety conditions.
"Some places expect you to buy your own tools, boots and clothes. There should be somewhere to wash your hands and somewhere warm and dry to sit down."
He added: "Many gardeners feel that their skills are not appreciated. We're not in a position to come up with pay scales like the old Agricultural Wages Board, but we would be able to give people a starting point on the salary and conditions they should expect."
PGG representative Sue Tasker added: "The guidelines will give members support to negotiate a rise if they are paid below the recommended rate, while members applying for new jobs are encouraged to check that the remuneration falls within the expected salary band and to negotiate or decline the post as appropriate."
The PGG had responses from 170 employed members and 55 self-employed members - a 22 per cent response rate. Almost half head gardeners (48 per cent) earn £20,000-£32,000 while 10 per cent earn more than £32,000. The highest earners are on £40,000-plus and the lowest £16,000-£20,000.
Tasker said this range, which bears little relation to garden size, location or number of staff supervised, suggests why there could be a need for guidelines.
Gardeners are more uniform, with 64 per cent earning £16,000-£20,000. Some earn significantly less, while only two are earning more.
Self-employed gardeners charge £10-£25 a hour, correlated with the part of the country in which they work, with the highest rates in London and the South East.
Salaries & rates PGG recommended bands
Gardens manager: £32,000 to £46,000+
Head gardener: £26,000 to £36,000+
Deputy head gardener/sole gardener: £22,000 to £28,000+
Gardener (skilled): £20,000 to £26,000+
Gardener: £16,000 to £21,000+
Junior gardener (age 17)/trainee: £14,000 to £16,000
Recommended minimum hourly rates for self employed work:
South East, including East Anglia: £17.50-£25;
Scotland, Wales and UK Regions: £15-£25.