Impressionist Gardens: how could the proposition fail? The most popular movement in art coupled with the reliable pleasure of gardens – it sounds such a calculated enterprise. Yet though it has roses, poppies and picnics in abundance, the National Gallery of Scotland's summer blockbuster turns out to be quite unpredictable. In this respect, it is the reverse of what one glumly imagined.  Take the utter strangeness of James Ensor's wheelbarrow in the foreground of an autumn garden. Sitting on a straight path that closely resembles the bottom ledge of a frame, it appears to be on our side of the scene observing the late blooms, an anthropomorphism emphasised by the two round cabbages that look out from the barrow like a pair of boggling eyes.  Ensor is painting Mr and Mrs Rousseau's garden in suburban Brussels; the picture is secretive, surreal. Arthur Melville's cabbages, flourishing in Scotland, are equally extraordinary: a tide of blue-green buoys lapping the legs of an East Lothian gardener  Sisley's garden outside Paris lies hidden beneath blue snow. James Tissot's back garden in St John's Wood is large enough for a full-scale impressionist pond. Gauguin, turning up in the most counterintuitive location in the show, paints skaters slithering on the outdoor ice rink of a Copenhagen park.  The unexpectedness of each scene is what strikes first. It is not just that each garden is different; in fact, very often they are not. Two artists may paint the same garden; two gardens, no matter how remote in terms of locale, may be planted with the same familiar flowers. It is more that each image is a painting first and foremost, of course, before it becomes a garden.  So the nasturtiums of Henri Fantin-Latour are hot-headed and impatient to rise to the fawn-coloured skies; while those of that highly intelligent and overlooked impressionist Gustav Caillebotte are veined and shy and persuasively wayward.  Renoir picks a bunch of camomile, ragwort and wild parsley to evoke the hazy summer fields round Fontainebleau, stuffing them into a homely jug to make the rustic point. The picture is comfortable in every respect. Delacroix's hothouse lilies and tulips, by contrast, make a wildly unquiet still life where there is no place for the eye to take a rest.  The more one peers into these paintings the more one becomes aware of each artist's characteristic strokes. Perhaps gardens are the perfect place to go to see mark-making at its clearest; used to describe the brush-sized details of petals, fronds, grass stems and mazy foliage.  The definition of impressionism is almost as broad as that of gardens, running all the way from Delacroix to Klimt. This is a bonus for anyone hoping to see more than sun-dappled meadows and ladies with parasols, though it means the show is somewhat overgrown. The garden, likewise, doesn't just mean a herbaceous border or fruitful orchard.  The definition takes in flower gardens, kitchen gardens, balconies, roof terraces, allotments and parks, which allows for the inclusion of William Merritt Chase's byway in Central Park, showing that curious fragment of American wilderness in the centre of Manhattan; and John Singer Sargent's Luxembourg Gardens at Twilight, the people breezing by beneath an electric silver moon, charged participants of modern life.  That there is a connection between the twin arts of gardening and painting is everywhere apparent. Look at the brilliant array of brushmarks in Van Gogh's Garden With Path, each graphic variation applied to a different species shimmering in the Provençal sun. Look at practically any of Monet's paintings of the garden at Giverny, specifically planted and maintained by six gardeners to be transformed forthwith into art.  We talk of gardens as blank canvases; of priming, designing and composition; of paint put on with a trowel and gardens as living art. But what you see here is just what a challenge gardens present to a painter. The eye rebels against any image containing hundreds of blossoms, as painstakingly enumerated by Klimt.  Conversely, when generalised, a garden may lack all focus, becoming a greenish blur, which exactly describes some of the second-rate impressionism included here.  Indeed, without wishing to downplay the horticultural theme, amply articulated flower by flower in the catalogue, the best of this show – its strongest focus – is not precisely to do with gardens.  On loan from Frankfurt is what looks, in this context, exactly like a sequel to Manet's notorious Déjeuner sur l'herbe, in which the four characters have picked themselves up from the grass, got dressed (in the case of the female nudes) and acquired the contents of a croquet set.  Who's playing whom, and in what respect, is the subtle game of Manet's painting with its oblique and flickering strokes. Everything shivers, including the atmosphere. The picture is beguiling and yet laconic.  In a tremendous final room, which brings Manet together with Van Gogh, Cézanne, Monet, Vuillard and Bonnard, the garden becomes the site of pure adventure. Modernism is growing fast in all directions wherever you look, from Van Gogh's exhilarating undergrowth of hectic marks to Cézanne's ethereal geometry and Monet's marvellous waterlilies.  These late works dissolve the distinction between surface and depth, near and far, atmosphere and form. The flowers have become light as air and almost as abstract. Pure beauty, pure optical pleasure: this is what they transmit. They may not seem very radical in social terms – pleasing pictures of popular flowers – but as art they are revolutionary.  Edinburgh, this summer, also has an exceptionally thorough survey of surrealism at the Dean Gallery, including some scintillating works by Miró, Man Ray and Max Ernst and a stunningly eerie boxed scene featuring twilight birds by the American Joseph Cornell. Small, sharp, articulate, droll, generally made off the cuff for friends, this is how one could describe the exhibits in Another World; it is what they have in common. In fact, what you see here as in no exhibition before is the sheer camaraderie – as opposed to the vicious factionalism – of the surrealists.  And the spirit of the letters and gifts displayed in glass cases throughout is carried into the work in surprising ways: the Dalí that looks like an Ernst, the Henry Moore that looks like a Dalí, the Picasso that looks like a Miró and so on.  Here are Miró's brilliant little ideograms, swarming across migraine-sharp horizons. Here are Magritte's great double-takes, Picabia's machine-part figures, Man Ray's verbal-visual puns. Each work speaks of larger ideas and, by the same token, the show as a whole is as succinct an anthology of an entire movement as possible.  For sheer graphic zip and register, for pictorial wit and intelligence, this is the strongest collection of surrealist art I can think of. And it is indeed a collection. Everything you see here belongs in perpetuity to the Scottish National Gallery of Modern Art.
In Edinburgh, the brushwork of the impressionists is laid bare in an exhibition of garden paintings, while an exemplary show reveals the dazzling wit and drive of the surrealists, writes Laura Cumming