Hertsmere Borough Council has completed a £1.5m project to restore the historic garden with the help of a £942,000 grant from the Big Lottery Fund's Parks for People programme.
Artist Sir Hubert von Herkomer, who owned the site and ran an art school there from 1833 to 1904, commissioned landscape designer Thomas Mawson to design the garden in 1913.
Hertsmere landscape design officer Fiona Leadley said: "The original structures were here, but all we had to go on were black and white photos and some aerial photos from the 1930s.
"I went up to the Mawson archives in Kendal to make sure that there weren't any plans and I found an image very similar to what we now call the rose temple."
Project manager Richard Stubbs added: "What we wanted to do in all aspects was a faithful restoration without overdoing the garden."
As a result of the lottery funding, full-time gardener Paul Knott has been hired to maintain the garden. "I've been working as a gardener for more than 20 years and specialise in roses. I breed them at home and have been doing that for around six years," he said.
"At the moment the watering has been quite tricky - I've been spending 70 per cent of my time doing it and that doesn't leave a lot of time for the other things. There are volunteers who are going to be helping out and at the moment we're advertising and will go through a selection process."
Hertsmere Borough Council hired Land Use Consultants to oversee the design of the project and construction firm Crispin & Borst to carry out the work on site.
The roses were supplied by David Austin Roses and the majority of the other plants were supplied by Robin Tacchi Plants.