Azalea

Rhododendrons are magnificent evergreen shrubs that produce enormous trusses of flowers in spring — from delicate whites and pinks to vivid reds, purples, and even yellows. They're woodland plants that thrive in dappled shade, acidic soil (pH 4.5–6.0), and sheltered conditions. On neutral or alkaline soil, they simply won't thrive — the leaves turn yellow (chlorosis) and the plant slowly declines. In such conditions, grow compact varieties in large containers filled with ericaceous compost, watered with rainwater. 'Cunningham's White' and 'Christmas Cheer' are among the hardiest large hybrids. For smaller gardens, the 'yakushimanum' hybrids are compact, dome-shaped, and incredibly floriferous. Deadheading after flowering (snap off the spent flower trusses carefully, without damaging the new growth buds beneath) improves flowering the following year. Rhododendrons have shallow root systems — mulch annually with leaf mould or bark to keep the roots cool and moist.

Holly is one of Britain's most iconic native evergreens — its glossy, spiny leaves and bright red berries are synonymous with Christmas. It makes an excellent hedging plant (dense, spiny, and virtually impenetrable to intruders) and a fine specimen tree. Holly is dioecious, meaning you need both male and female plants for berries — the female produces the berries, but only if a male is nearby for pollination. Confusingly, some varieties have misleading names: 'Golden King' is female (with berries) and 'Golden Queen' is male. 'J.C. van Tol' is a useful almost self-fertile variety. Holly tolerates heavy shade, pollution, coastal exposure, and most soil types — it's one of the toughest plants in the British garden. It can be pruned hard and topiarised into shapes. The berries provide vital winter food for birds, particularly thrushes and waxwings. Holly grows slowly, so buy the largest plant you can afford for hedging purposes.

Hydrangeas are among the most popular garden shrubs in the UK, valued for their enormous, long-lasting flower heads in shades of blue, pink, purple, and white. The flower colour of mophead (Hortensia) and lacecap types is famously influenced by soil pH: in acidic soil (below pH 5.5) they produce blue flowers; in alkaline soil, pink. To keep blue flowers blue, add aluminium sulphate or use ericaceous compost; to keep pink flowers pink, add lime. White varieties stay white regardless. 'Nikko Blue' and 'Endless Summer' are popular blue varieties; 'Madame Emile Mouillère' is the best white. Hydrangeas prefer partial shade — hot afternoon sun scorches the leaves and flowers. They need consistently moist soil and will wilt dramatically in drought (though they recover quickly after watering). Prune mophead and lacecap types in spring by cutting just above the first pair of healthy buds below last year's flower head. The dried flower heads provide winter structure — leave them on until spring.

Heather (Calluna) is the plant that paints the moors purple in late summer and brings the same wild beauty to garden settings. These low-growing evergreen shrubs form dense, weed-suppressing mats of tiny leaves, topped with spikes of small flowers in shades of purple, pink, red, and white from August to November. They need acidic, well-drained soil and an open, sunny position. On alkaline soil, grow in raised beds or containers of ericaceous compost. Combined with winter-flowering heaths (Erica carnea and E. × darleyensis, which tolerate alkaline soil), you can have heather in flower every month of the year. Heathers look best planted in sweeping drifts of 5–7 plants of the same variety, with different varieties blending into each other. Clip annually with shears after flowering, removing the faded flower spikes and a little of the leafy growth — this prevents the plants becoming leggy and bare at the base. 'Firefly' has striking russet foliage that changes colour through the seasons.