Fast Growing Shrubs

(Buddleja if you want to be pretentious) Medium to large shrub, fast growing (stand well back) covered in fragrant purple cone-shaped inflorescences 4"-12" long in summer that are in turn frequently covered in butterflies. 

Flowers of different varieties come in shades from white through lilac to quite dark purple with pinks too. There's also an orange flowered variety B. globosa with golf-ball sized and shaped inflorescences. The star of the group for my money is Buddleia alternifolia, though not as tough or quick as davidii.

Evergreen shrub, blue flowers in spring, small mid green leaves about 1-3" long. To 6m (20ft) high and wide, though easily kept in check by pruning. Variety "repens" frequently sold - creeping  blueblossom, height and spread from about 1-2.5m (3-8ft).

Eucalypts are a genus of trees that if left to their own devices that will go to 50ft +, if they're happy. However, don't be too alarmed. What you need to do is treat a Eucalyptus as a coppice stool. Let the plant get established for one or two years and then in Feb / March you cut it down to about 4-6" above ground level. This encourages it to throw out new shoots from just below the cut point. The plant will then provide you with lots of very attractive glaucous blue/green juvenile foliage that can grow up to 6ft from ground level in a season. It's also reputed to keep midges and mosquitoes at bay, so plant it near the patio.

A very beautiful foliage plant, excellent against rather dull fences and as a contrast to other leaf colors and shapes. Tends to be a bit fussy about position. Likes to be well drained so incorporate lots of sharp sand and / or pea shingle when planting it and only plant in full sunshine, otherwise 6ft growth a year becomes 6mm.

    Lavatera - Mallow  S

There are annual and perennial varieties, all are fast growing, this describes the perennials. Woody shrub with masses of pink flowers about 3" across over long period in summer. Semi-evergreen, to about 6ft wide and tall given the space, unfussy about position but do better in sun. "Barnsley", pale almost white flowers aging to mid pink. "Bredon Springs", dusky pink, "Rosea", rose pink. Short lived but easy to propagate in early summer.

Large dense, bushy evergreen shrub. Long glossy leaves to about 6" long, dark green above, lighter below. Fragrant white flowers produced in spring. With the (quite deserved) decline of x Cupressocyparis lleylandii as a hedging plant, laurels should be the ideal replacement. They are dense and fast growing, but respond better to trimming and don't just proceed skywards indefinitely.

 Whereas conifers rarely if ever grow from brown wood, even old established laurels will respond to a severe pruning by producing fresh green growth from mature brown wood that hasn't seen direct sunlight for years. Within a year or so, you will be rewarded with a new curtain of attractive foliage. 

Don't trim with shears though, the large leaves don't look good when they start to turn brown at the edges after being chopped through. A smaller variety "Otto Luyken" grows to about 3ft tall and wide and is suitable for inclusion in a border.

Tough and hardy, a single plant may be grown as an informal wind-break or at the back of a large border where the dark green leaves set off other foliage and flowers admirably.