Royal Botanic Gardens, Kew (near London): A delight in any season, everything blooms in profusion in this 300-acre garden, from delicate exotics to commonplace flowers and shrubs. It's all part of a vast lab dedicated to identifying plants from all parts of the globe and also growing some for commercial purposes. An easy trip from London, Kew Gardens, as its known, possesses the largest herbarium on earth. Fabled landscape architect Capability Brown helped lay out part of the grounds.

Sissinghurst Castle Garden (near Maidstone, Kent): A notorious literary couple, Vita Sackville-West and Harold Nicolson, created this garden in sunny Kent. Its flamboyant parentage, unusual landscaping (the grounds were laid between the surviving parts of an Elizabethan mansion), and location just 34km (21 miles) northeast of Cranbrook make it the most intriguing garden on London's doorstep. Overrun by tourists in summer, it's lovely in autumn, when the colors are at their dramatic best.

Wisley Garden (Wisley, Kent): Wisley Garden sprawls across 250 acres, filled with an abundance of flowers and shrubs. Maintained by the Royal Horticultural Society, it ranges from alpinelike meadows to summer carpets of flowers. In early summer, the gardens are brilliant with flowering rhododendrons. The landscaped orchid house alone is worth the trip here.

Stourhead (near Shaftesbury, Dorset): Outside of the Greater London area is the most famous garden in England. The birthplace of English landscape gardening, Stourhead is still the best-executed example of the taste for natural landscaping that swept England in the 1700s. The grounds have been likened to a 3-D painting of an old master such as Constable. The gardens are a wealth of flowering shrubs, trees, and beds upon beds of multihued blooms. Grottoes, bridges, and temples also add to the allure.

Hidcote Manor Garden (near Chipping Campden, in the Cotswolds): Just outside one of the Cotswolds' most charming towns lies this stunning garden, laid out around a stone-built manor house. It's the largest garden in the Cotswolds, and one of the most intriguing in all of Britain. The garden originally bloomed under Major Lawrence Johnstone, an American horticulturist who created it in 1907. He traveled the world and brought back specimens to plant. It shows.