Is gardening the new cooking? Suddenly everyone is digging in, from Michelle Obama to Britney Spears and no chef worth their Maldon is without their own, fully stocked kitchen garden, whether it's Michael Caines, Jamie Oliver or Nigel Slater.

For some, though, gardening and cooking are one and the same, as cooking with flowers becomes increasingly fashionable in foodie circles. At the forefront of this new vogue is Skye Gygnell, head chef at the appropriate setting of Petersham Nurseries in Richmond. In this sunny, riverside Eden, the somewhat bohemian restaurant evolves symbiotically with the plants in the public nursery and the private walled kitchen garden that feeds the diners.

Voluptuous peonies have burst into flower, exotic parrot tulips and blowsy ranunculus nod in the warm breeze as fat bees, drunk on nectar, wobble from one flower head to the next. Against the walls, cherry blossom soaks up the heat while plucky, hardy salad leaves, leeks and chives have recently surfaced from the ground and are romping on thanks to an unusually mild April.

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Here, flowers are grown both for the tables in the restaurant and, less typically, for the dishes that are served up, too. "Just look at the colours of these tulips," enthuses Gyngell as she shows me around, naming each variety. "Isn't nature amazing – you couldn't create these colours and patterns, it's just incredible. It would be impossible not to be inspired by this environment and so incorporating flowers into my cooking comes very naturally. I just have to look around for ideas."

In the neighbouring glasshouse, Gyngell shows me peaches unfurling from their winter slumber and explains that, as members of the almond family, even the leaves will infuse a dish with an almond scent. She also uses rose petals to create a fragrant syrup that makes melon sing of summer, and crystalises violet petals for an intense burst of flavour that you're probably familiar with from the childhood sweets Parma Violets. "Roses just arrest your senses so that you don't know whether you are tasting or smelling them and they just epitomise an old-fashioned English summer day – it's such an evocative way to cook because it's more than just tasting the food, it becomes a sensory experience." But Gyngell is at pains to point out that she only cooks with flowers when they add something to the dish: "I love the way flowers look and the colours that they add to a dish but I never use them purely as a garnish, they have to enhance the food, otherwise it just looks twee and feels pointless to me."

She's not alone in this culinary reinterpretation of flower-arranging. At the Star Inn in Harome, chef Andrew Pern uses home-grown lavender to make ice cream and at the Icelandic restaurant Texture in London Agnar Sverrisson has made flowers an integral part of his cooking. "We use all kinds of flowers but one of my favourites is rose water chocolate mousse, with rose petals, dried and fresh," explains Sverrisson. Meanwhile, to celebrate the upcoming Chelsea Flower Show, Tom Aikens has created a five-course flower menu.

Richard Vine, a culinary flower grower who supplies top restaurants and chefs (including Aitkens), says cooking with flowers is catching on fast. "We've never been so busy growing and supplying flowers to restaurants, we're working flat-out right now. But we're also noticing increasing enquiries from members of the public who want to replicate meals they've had in top restaurants using flowers – things like borage, pansies, violas, honeysuckle, garlic chives, nasturtiums, beans and peas. I can remember foraging for hawthorn flowers and leaves to put in salads as a boy – but it's something that the public had forgotten that we used to do."

What is most surprising is the number of flowers that can be eaten and the amount of flavour they contain. All roses are edible and have a slightly fruity flavour that can be used to make syrups or jellies; honeysuckle, as the name implies, has a sweet honey taste, while the highly scented jasmine flower is used to flavour rice and tea. Hibiscus tastes citrussy, while lilac flowers have a slightly bitter lemon-y flavour that gives a zing to salads. Orange flowers have been infused for years and used in cakes and desserts.

Flowers aren't just for desserts, though. Many have a savoury taste and can enhance salads, stews, meat and fish. Some flowers taste more mild than others – basil and rosemary flowers, for instance, are a more subtle version of their leaves, while chives, rocket and garlic flowers are stronger, as the flowers grow after the plant has bolted – the leaves become increasingly strong with age, so by the time the plant flowers, the flavours are intense.

Wild garlic is in season now and the white, round allium-like heads can be found under hedgerows and in woodland throughout May. While the individual, bell-shaped flowers look beautiful, they are strongly flavoured so are best used sparingly, says Sverisson. At Texture, he is using them with lamb and beef, while at the ethical eatery Acorn House they are making a wild garlic flower and pistachio pesto.

The natural sugars in fresh peas and broad beans extend to their pretty black-and-white flowers, too, making them a favourite for dressing starters and salads. Tom Aikens has broad-bean flowers and shoots on his menu, served with a broad bean mousse and cabecou goat's cheese. "Because the flower of the plant becomes the vegetable, when it comes to peas, broad beans and tomatoes, you can get a very intense flavour from the flower," says Aikens. Dill flowers work with fish just as the leaves would, and Aikens has combined scallops with peppery nasturtium flowers and salmon with radish and whole Viola flowers for his floral menu. Agnar Sverrisson is a fan of little baby violet flowers with fish, "They're great with salads and raw fish, such as sushi or sashimi. We also like to use them with crab, which works really well."

If you want to cook with flowers at home, remember to use flowers that you know haven't been sprayed with chemicals – supermarket roses are almost certainly a no-no – and remove the central pistil (the stamen, anthers and stigma). Some of the easiest to use are herb flowers, which you can use in the same way as you would the herbs – just let the plants run to flower and then pick them off.

But perhaps the simplest floral recipe to try is borage – the star-shaped blue blooms grow wild in many gardens and have a delicate cucumber taste. Throw a few flowers into an ice-cube tray to make floral cube that can be added to a glass of Pimms for an instant touch of style.

Petal power: How to cook with flowers

Courgette flowers

Use the male flowers (as these don't grow into courgettes) and stuff them with ricotta, parmesan, lemon and mint then fry them, or batter them and deep-fry for an Italian-style tempura. Squash and pumpkin flowers work just as well.

Elder flower

Use the sweet, delicate flowers in a refreshing sorbet or cordial, or ferment them to make Elderflower champagne: dissolve 400g of sugar in 800ml of hot water, then top up with 1.2 litres of cold water. Add the juice and zest of one lemon, a teaspoon of white wine vinegar and five elderflower heads and stir gently. Cover with muslin and leave to ferment for two days. If it hasn't become foamy by this point add the tiniest pinch of yeast. Leave for another four days, strain the liquid and decant into bottles and leave for another week before serving chilled.

Nasturtium

A fast-growing, pretty, trailing flower that thrives in most soils as long as it gets plenty of sun – all parts of it are edible. Add the bright orange peppery flowers to salads or as a garnish to pasta dishes for a colourful kick. The seeds can also be pickled as a substitute for capers.

Basil

Add a handful of the antioxidant-rich flowers to a jam jar and fill it with cheap olive oil. Leave to infuse for a couple of weeks for a delicately flavoured oil that you can use as a salad dressing or for dipping bread into.

Marigolds

Marigolds have a tangy, peppery taste that makes them great for salads or soups, or added to cream cheese for sandwiches. It also gives a beautiful saffron colour to your cooking.

Rose

The stronger the fragrance of the flower, the more sweet and aromatic the flavour will be. Rose petals are a good source of vitamin C and other anti-oxidants. Try making a syrup with a handful of petals (remove the white inner tips of petals to avoid bitterness), water and sugar and then drizzling it over ice-cream, melon or adding it to champagne.

Sea Kale

Jamie Oliver recommends serving the small white flowers with strawberries – while the delicate, "nutty" stems are eaten in winter, the smoky grey leaves and clouds of white blooms look lovely in the summer. It's a native coastal plant but loves any sunny, well-drained spot. Plants can be bought from Jekka's Herb Farm (www.jekkasherbfarm.com).

Borage

Growing in many people's back gardens, the blue, star-like flowers taste of cucumber and go well with apples and pears – try a borage Waldorf salad. Or why not drop them in an ice-cube tray and add to your Pimms.