This is one of the best Hampton Court flower shows in its eighteenth-year history – great gardens, gorgeous planting and brilliant ideas with sustainability taking centre stage. And, at last, the sustainable ideas here are entertaining as well as worthy.

For instance, one space-saving feature involves a heavily-planted Bentley emerging over a pool, Excalibur like. It’s bonkers, wonderful and it’s also green - the 1966 car is part of film-maker Anthony Samuelson’s fleet of gas guzzlers that he’s abandoning in the name of sustainability.

This year’s particular obsession with garden-show greenness reared its head at the Chelsea Flower Show where the forum I chaired was rife with passionate talk about green gardens. The talk is walking at Hampton Court.

Chris Beardshaw, one of the forum’s most popular speakers, has built the biggest garden here with the help of nearly 500 school children. They’ve grown so many plants and made so many ornaments (from tiles to terracotta mini beasts) that it’s expanded from 30x20 metres to 30x30 metres and, just now, has had to spread further into the Royal Park to make room for some full-size sheep sculptures. "They even smell like sheep," said Chris, who admitted this was the most difficult garden he has built because of its diversity and the number of people involved.

Using recycled materials Chris has created a school playing field with mass of habitats and features - meadow, woodland, arid and wetland, fruit, vegetables, a cob study centre made from straw bale walls clad in lime daub, an amphitheatre, a willow nest on a sculpted earth mound, a poetry and story telling area, a recycling centre, a climbing wall and a willow woven ‘green man'.

"The computers inside the study centre are solar powered. The whole of this building cost £5,000 but that includes labour. With parents it needn’t cost much," said Chris, who pointed out that the ideas here are aimed at any school from inner city through to urban and rural. "We’ve made a CD to show teachers how aspects of gardens and gardening fit into the national curriculum. The CD is free from the DFES," he continued.

Chris owes his passion for education to that fact that his school tried to stop him studying anything to do with horticulture on the grounds that he was too clever. "Gardens key into everything – science, architecture, art and lots more," he said, his own garden being an eloquent expression of his philosophy.

Still on a school theme, the youngest designers in the show are the six- and seven-year-olds from Alton Infant School in Hampshire who have created a stunning garden – the type you feel you want in your own backyard. Their garden’s theme is ‘learning to looking after the world’.

‘We made the stepping stones from broken tiles and the scarecrow we made is called Hairy Harry’ said one of the designers, seven-year-old Lewis Jones-Ayres. "The garden’s good – it’s just how we designed it."

The plot, made from recycled materials, mirrors their own school garden with a fruit and vegetable area, pond, wild and sensory garden and a wild flower patch. And chickens – yes live ones - because the school hatches its own chicks.

I spoke to Ann Foulkes, department head of the school, in a snatched break while she was constructing the garden. "I have a group of children who are called the Gardening Committee. We give them projects to stretch them and to problem solve in the real world. In September, we started brainstorming ideas for a show garden. We laid them out on a 6x4 metre area of the school playing field using paper for ponds and so on to see what it would look like. Then we drew a scale drawing and sent it to the RHS," she said. Health and Safety laws prevented the children being involved in constructing the garden.

Health and Safety had a bit of a struggle over another show garden - which has been made in a skip. Skips are usually part of the show’s build-up when everyone has to wear high-visibility jackets and stick to strict Health and Safety rules. This skip stayed behind and it’s been designed by the London Wildlife Trust and the Royal Parks using leftovers from the Chelsea Flower Show. The end result is a sustainable garden for people and wildlife which uses drought tolerant planting and a range of herbs, shrubs, wildflowers and grasses with nectar-rich flowers or seed heads to attract insects and birds. And a solar-powered shower running into an old bath tub makes one of the more bizarre centrepiece’s of the show.

The point of making this ‘Wildlife Garden in a Skip’ is to highlight the fact that many of London’s gardens are being annihilated by development and paving and, if you can’t see it at the show, you can always request that the garden comes to you via the website link above.

Hadlow College has come up with this year’s 'big' idea. It’s brilliant. A fern pit covered by a grating giving cars a place in the front garden without loosing any planting space. Think about it – the ferns get light and water while the planting continues to prevent run off and do all the other excellent things that plants do for us - like giving us air to breathe. A fern pit is a great feature for any small or shaded garden where grass will never grow well.

The rest of this small garden includes drought-tolerant planting like Macleaya, Eschscholtzia, Sempervivum, Thymus, Origanum, Hedera, Ajuga and wildlife friendly planting like Lonicera ’Graham Thomas’, Hedera, Eschscholtzia, Ajuga, Origanum, Thymus, Nepeta, Cosmos, Echinops.

As if to remind us all that climate change is something we need to address urgently, the show site is a quagmire - but it’s well worth a visit so long as you take your waterproofs.