Gareth Carter: Fill your garden with the joy of perennials

Bearded iris has numerous flower colours and patterns in almost every colour imaginable.

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 where they may die back to a few sticks but not flowers and some perennials such as hostas that 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 such as 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.

Some unusual, rare and common perennials to look out for include:

Trillium

Spring flowering woodland perennial with unusual three-petalled flowers. They form clumps with increasing flower quantities as they get older. Flowers colours include white, cream, pink to deep maroon red. They grow best under trees in a shady position, reaching 15-50cm high.

Thalictrum delavayi

These herbaceous perennials emerge from dormancy every spring, producing attractive fine dainty looking maidenhair fern-like foliage. From the foliage attractive flower spikes of purple-mauve colour emerge during late spring and summer, putting on a great show. There is also a white variety available (Thalictrum delavayi alba).

Thalictrum

Bearded iris

These have fleshy rhizome-type roots and generally leaves all year round. During the late spring and early summer period they produce spectacular flower spikes. They grow best in a well-drained situation. There are numerous flower colours and patterns in almost every colour imaginable.

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 and 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, purple, and blue in varying shades. Best in full sun.

Delphinium

Lily of the valley

Sought after for its fragrance, this bulbous perennial is dormant all winter, popping into life in September each year, 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 approximately 15-20cm high. Great in part shade positions under trees.

Lilly of the valley

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 & Pelargonium

These plants are easily maintained perennial plants for pots, window boxes and hanging baskets as well as in 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, and the breeding programmes of these plants give an exceptional ability to repeat flower with high intensity throughout most of the year while maintaining an attractive compact and bushy growth habit.

Heuchera

Grow well in full shade to half shade position, moist soils, approximately 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 Plum Power, Northern Exposure Amber, and Black Taffeta – all stunning.

Hosta

Hosta 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.

Gareth Carter is general manager of Springvale Garden Centre.