Themed holidays have been around for a long time, suited to hobbyists whose pastimes have included painting, cooking or indeed gardening.

While garden-themed holidays simply used to involve trips to well-known gardens to admire the scenery and perhaps enjoy a guided tour, today's offerings are more sophisticated, and if you pick the right holiday, you may have smaller groups, visits to private gardens and even a bit of hands-on experience.

Tailor-made garden cruises featuring talks by TV gardening experts, visits to exotic gardens where guests can sample the locally grown tropical fruits and trips which incorporate some of the major horticultural shows are all available.

Kew-trained horticulturist Sue Macdonald, who founded Boxwood Tours ( in 1990, which specialises in quality garden holidays, says that green-fingered travellers are becoming more discerning.

"They want more private visits and want to meet the garden owners or head gardeners. That's a big draw on a tour. They want to hear about the garden, how they cope with recent weather difficulties and plans for the future. They need someone there who can tell them the key information.

"Gardeners want a tour leader with a horticultural background, rather than just going around a National Trust property without meeting anybody, just looking. They want questions answered."

Some organisations offer workshops for people who want to learn some practical gardening, but they are difficult to incorporate on a garden-themed holiday, Macdonald explains.

"Setting up tours which are more practical is not easy to do because it involves extra insurance if people are using knives or pruning shears or digging.

"Gardens also have to have enough space to bring people in for hands-on gardening experiences, so they might need enough space to take a group of 10 people, for instance, to take cuttings from a shrub."

But the yearning for knowledge among travellers is ever-increasing, she points out.

"We have started looking more at different plant groups, which we're doing on our Cornwall tour this year, so the head gardener is going to talk about and demonstrate the propagation of camellias, but it's not set up like a workshop."

The Royal Horticultural Society recently launched its first ever RHS Garden Holidays brochure in conjunction with escorted tours expert Collette Worldwide Holidays, featuring horticulture-themed holidays around the world, including itineraries to the US, New Zealand, South Africa, Japan, The Azores, France, Italy and Spain.

Celebrating the centenary of RHS Chelsea Flower Show, its China tours follow in the footsteps of the original plant hunters and offer visitors an element of discovery.

"For somebody who really wants to get down and dirty in plant hunting, looking under rocks, in damp bark, under leaves, up in the trees, in search of orchids or clematis or magnolia or whatever we are looking for, following in the footsteps of the original plant hunters, the plant seekers' trip would be one for them," says Sue Biggs, RHS director general, who has a background in travel.

Biggs notes: "A lot of people will be happy to go to beautiful gardens, be told what the plants are and where they grow best and how to grow them at home, but if you want really top level - where you find out the Latin names, how to cultivate and graft plants, the real horticultural knowledge, then it would be best to choose a tour that's escorted by an RHS curator or horticultural specialist."

What to look out for:

:: Check the inclusions because you may discover that food is not included and optional excursions can bump up your costs.

:: Take note of single supplements. Many gardeners go on horticulture-themed holidays on their own.

:: Look for unique experiences where you won't be on a well-worn trail behind a fleet of other tourist coaches.

:: Try to find out the calibre of your tour escort - are they just a courier or a horticultural specialist with plenty of knowledge?

:: Consider the schedule carefully. How many gardens a day will you be covering? You might only be doing three or four gardens in the whole tour and be at the hotel the rest of the time.

:: Watch out for the term 'private visits' because the garden may be privately owned but open sometimes to the public. You may be greeted by crowds if you go on a day when it's open to the public.

:: Don't always go for the peak time. There's a broader season and lots to see - without the crowds.

:: Check group sizes. A good yardstick is 25 maximum to be able to see and hear most things, but if you are visiting a small garden, even that can be too many.