Trillium plants have unusual three-petalled flowers. Photo / Supplied
Perennials are flowering plants that last a number of years.
They are often seasonal in nature with a period of high colour and then a time of dormancy, or stasis, when they may die back to a few sticks but no flowers. Some perennials, such as hostas, do go completely dormant.
Perennial plants repeat their cycle year after year, gradually increasing in size and number. There is a huge selection of perennials that can add interest and colour to the garden in summer and they come in all shapes and sizes.
They often make a garden theme, such as a cottage garden, where they can be companions for more permanent plants like roses and trees. Herbaceous perennials such as hosta and astilbe emerge during spring, flower in summer and die down and become dormant in winter. They enjoy cool garden conditions.
Perennials can complement many trees, shrubs, roses, annual flowers and bulbs. Many provide excellent flowers for indoor use. Others have attractive foliage in bronze, yellow-green, grey and silver. Perennials prefer some good compost added to the soil with slow-release general fertiliser like Ican Slow Food when preparing to plant.
Unusual, rare and common perennials
Trillium
Spring flowering woodland perennial with unusual three-petalled flowers. They form clumps with increasing flower quantities as they get older. Flower colours include white, cream, pink to deep maroon red. They grow best under trees in a shady position, reaching 15-50cm high.
Candelabra primula japonica
This is a herbaceous (leafy all year round) perennial with bright flowers on 30cm stems in late spring and early summer. Thrives in the shade. Comes in a range of colours including white through pink to red.
Oriental poppy (papaver)
These are darlings of the summer with flowers on single stems, sometimes up to 75cm tall, arising from sturdy clumps of bristly blue-green leaves. Best in a sunny spot, flower colour ranges from white with a strong purple blotch to pastel coral pinks and many other colours.
Delphinium
These eye-catching perennials produce tall spires of blooms generally ranging from 50-80cm in height during the summer months. The root system develops and expands each year so the plants will carry an increasing number of blooms. Thanks to years of breeding and multiple crosses, there is a wide array of colours available from white, pink to purple and blue in varying shades. Best in full sun.
Lily of the valley
Sought after for its fragrance, this bulbous perennial is dormant all winter, popping into life in September each year and producing flower spikes in October. Leaves continue during summer before going dormant for the autumn and winter. The flower stems have numerous fragrant dainty blooms. Grows about 15-20cm high. Great in part-shade positions under trees.
English snowdrop (galanthus)
Striking bulbous perennial that flowers during the winter months. Foliage then dies down during the summer months to re-emerge in late autumn. There are a number of varieties including the Giant Snowdrop (Galanthus elwesii) and Double English Snowdrop (Galanthus Flore Plena) to name a couple. They like a cool, moist position and reach about 20cm high.
Osteospermum
Also known as cape daisies, these plants are hardy to conditions ranging from coastal wind and hot sun to semi-shady positions. They boast a continuous flowering habit with blooms almost year-round. They are drought-tolerant and look great in containers and garden situations.
Geranium and pelargonium
These plants are ideal and easily maintained perennial plants for pots, window boxes and hanging baskets as well as garden plots. They thrive in most soils in sunny positions. Regular pruning after flowering keeps the plants compact. Popular flower colours are red, white, pink and mauve. Ivy (climbing) geraniums have long stems for trailing over walls and fences or for trailing over banks. They are also suitable for hanging baskets. The Pac range is exceptionally good. The breeding programmes of these plants give exceptional ability to repeat flower with high intensity throughout most of the year while maintaining an attractive compact and bushy growth habit.
Heuchera
Grows well in full shade to half-shade position, moist soils, about 30x45cm. They produce stunning foliage to add year-round colour in gardens with clusters of small coral pink or white bells in spring and autumn. They love shade so are ideally planted under trees and shrubs or on the shady side of the house. Look out for varieties Marmalade, Plum Cascade and Plum Royale – all stunning.
Hosta
Hostas grow well in full shade to semi-shade positions, most in the 25-40cm range. They form handsome leaf colours and textures from bright chartreuse (yellow and green) through forest greens, icy blues and silver greys and cream or yellow variegated foliage forms. They have small bell-shaped white or lilac flowers, sometimes fragrant in summer. They thrive in moist well-drained soils with plenty of compost added. Feed in the spring and mulch with compost, straw or similar to keep them cool and moist. Always be ready with slug and snail bait from early spring as they are often subject to voracious attacks.
For more gardening information visit www.springvalegardencentre.co.nz
• Gareth Carter is general manager of Springvale Garden Centre.
'We want to take a very detailed specific look at what Whanganui needs' – Chris Bishop.