With temperatures in London reaching 30C last week, the build-up at this year’s Hampton Court Show involved feverish snipping of dead heads and twice-daily watering. The challenging conditions seemed to confirm the climate change trends presented in the show’s Garden Energy exhibit. Display boards announce that of the UK’s ten warmest years on record, eight of them have occurred since 1990 and that gardeners should adopt water-saving measures and grow drought-resistant species such as marigolds, geraniums and petunias. Marigolds add zing to many of the planting schemes but geraniums, because of the hot weather, peaked early and have gone over. For the same reason Philippa Pearson had to drop verbascums and salvias from her vibrant design for the Sadolin Nature to Nurture Garden (GW4) but has had no problem using later-blooming echinaceas and crocosmias.

Day lilies, too, are a leitmotif in many of this year’s gardens. The grower Chris Bonanni, of Coldharbour Nursery, is showing a number of striking spider forms, with petals five times longer than their width, in the Floral Marquee.

The Garden Energy exhibit suggests a palette of spiky succulents, eucalyptus and loquats for gardens in 2050 but an exquisitely conceived small garden by the Slovenian designer Berut Benedejcic gives us a range of attractive herbs, fruits and flowering plants, including sedums that spill down the stone walls. This re-creates the native flora of the Karst region, where summers are hotter and drier than in the UK and the spring months are wetter. The small-flowered bright pink pelargonium below the open window of the village house has leaves that give off a pungent earthy smell, which apparently keep flying insects out of the house.

Beneficial insects, though, are offered plenty of feeding stations at the show not only from the ornamental plants but also from wildflowers which are incorporated into various gardens — main, small, sustainable, edible and on rooftops. The meadow area in the Pastures Bye garden (GW9) features the delicate Deptford pink (Dianthus armeria), a South of England wildflower. A Beekeper’s Garden (GW2) is a confection of elegant bee-friendly plants such as agapanthus, cardoons and eryngiums — bees prefer ultraviolet colours — combined with vegetables and apple trees.

It’s hardly surprising that the Grow Your Own theme has been adopted by so many designers. Novices may not be persuaded to grow their produce in XL-sized underpants and bras as shown on one display, but there are plenty of inspiring ideas from Karen Rogers’ small garden, A Chef’s Kitchen, where pots dangle from the pergola, to the replete allotment garden outside the Growing Tastes Marquee. Secondary school students at Whitgift School in Croydon, will look out on the Hidden Treasures garden, which was put together in only six weeks by the estate manager of the school, who incorporated two topiary galleons and set them in a sea of lavender and blue festuca grasses with the soft pale tips of Stipa tenuissima, suggesting the froth of the waves.

Rose lovers should head for the Tudor Rose Festival marquee and inspectthe butter yellow Absolutely Fabulous which is Rose of the Year for 2010 and the stunning Celebration Time, with buds of terracotta red that open to a rich raspberry overlaid with grey and with plum-coloured young foliage. It’s a real show stealer.

Hampton Court Palace Flower Show continues until July 12 rhs.org.uk