Most of the following shrubs grow no more than 60 to 90 centimetres wide, about the same diameter as a drift of three to five perennials. All are hardy to Zone 4, except euonymus, kerria, butterfly bush, some cotoneasters, St. John's wort, daphne, deutzia and false cypress, which are all hardy to Zone 5.
A common shape of many shrubs, as well as perennials, a mound works well in the middle or front of a border and offers a smooth transition from one section to another.
St. John's Wort
(Hypericum kalmianum, 60 cm tall, 90 cm wide)
This shrub will provide a burst of bright yellow in July and August, and its blue-green leaves are a good foil for the blooms. Another woody species, H. androsaemum ‘Albury Purple' (80 cm tall, 50 cm wide) has dusky burgundy foliage-a striking contrast to the yellow flowers.
‘Carol Mackie' Daphne
(Daphne burkwoodii ‘Carol Mackie', 80 by 80 cm)
A highly fragrant shrub, it has leaves outlined with a thin, cream-coloured margin and pink flowers in May and June. Another small, deciduous daphne is D. mezereum ‘Ruby Glow', which has fragrant, dark pink flowers in April.
(Deutzia x lemoinei ‘Compacta' and D. scabra ‘Pink Pom-Pom', both 1.2 m tall, 1 m wide)
‘Compacta' has white flowers in June, while ‘Pink Pom-Pom' has pink double blooms. The latter cultivar's leaves turn a deep burgundy in fall.
Breeders have spent several years tinkering with this species, resulting in introductions that offer relief from the screaming yellow flowers of earlier cultivars. Now we can choose from a wide range of deliciously coloured varieties such ‘Mango Tango' and ‘Orangeade', as well as ‘Pink Princess', ‘Pink Beauty', ‘Red Robin' and ‘Red Ace'. These range in height from 40 to 90 centimetres, forming clumps 60 to 90 centimetres wide. Best of all, potentillas bloom from June to September (few perennials can match that) and many have dainty, blue-green foliage.
This shrub family is blessed with many small cultivars, including S. japonica ‘Anthony Waterer' (1 m tall) with rosy flowers, S. j. ‘Little Princess' (60 cm tall) with lighter pink flowers, and S. j. ‘Shirobana' (60 cm tall) with pink and white flowers on the same plant. All bloom in July and reach no more than 80 centimetres in width. Often, foliage turns a lovely burgundy in fall. Another small spirea is S. j. ‘Goldmound', which has pink flowers and bright yellow foliage, a rather lurid combination that I find difficult to work with, let alone look at. Sometimes hybridizers need to know when to stop.
This shrub flowers in June, and often again in August, with blooms much loved by hummingbirds. ‘Minuet' has green leaves with purple edges and pale pink flowers; ‘Carnaval' sports white, pink and red flowers, all on the same plant. ‘Midnight Wine' has purple leaves and deep pink flowers. All three reach about one metre in height and diameter.
‘Little Gem' Norway Spruce
(Picea abies ‘Little Gem', 60 by 60 cm)
This slow grower has tiny needles. Other short-statured species to look for are dwarf black spruce (P. mariana ‘Nana', 75 cm tall, 1 m wide) and dwarf Serbian spruce (P. omorika ‘Nana', 1 m by 1 m).
Dwarf Hinoki Cypress
(Chamaecyparis obtusa ‘Nana Gracilis', 1.25 m tall, 60 cm wide)
A very slow-growing plant that sports bright green, fan-shaped foliage.
Dwarf Balsam Fir
(Abies balsamea ‘Nana', 60 cm tall, 1 m wide)
This variety has both mounding and arching habits. If your border is in a sheltered location where dessicating winter winds won't wreak havoc, consider some of the small broadleaf evergreens. Examples include boxwood (Buxus cvs.), ‘Vancouver Gold' broom (Genista pilosa ‘Vancouver Gold'), bearberry (Cotoneaster dammeri) and variegated euonymus (Euonymus fortunei ‘Surespot' and ‘Emerald 'n Gold').
Photo: 'Ruby Glow' Daphne, Aleksandra Szywala