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Perennials

The permanent structure of your garden

Perennials are plants that live for more than two years (as opposed to annuals – one year – and biennials – two years). This can be for three-four year (often termed short-lived perennials to the oldest living things on the planet, trees.

Mix in the fact that the woody trees and shrubs can be evergreen, for winter interest or deciduous, for dynamic changes from spring to autumn and your garden can’t do without them.

Trees

The definition of a tree is: “a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at some distance from the ground.”

However, trees can be tiny in the gardening world, growing on dwarfing rootstocks or kept small by pruning (think bonsai).

Trees are so special because of their great age and ability to house whole ecosystems. The oldest individual tree in the world is thought to be a Great Basin bristlecone pine (Pinus longaeva) living in the White Mountains of California at an astounding 5,062 years old.

However, the oldest living plant organisms in the world are not individuals – they are ‘clonal colonies’ – genetically identical trees connected by a single root system.

The Pando, or “trembling giant,” is a clonal colony of more than 40,000 individual quaking aspen (Populus tremuloides) in Fishlake National Fores, Utah, thought to be 80,000 years old.

How do they do this? Well, some coniferous trees can reproduce with the root penetrating branches to produce clones, so individual trunks are much younger.

Next time you’re tempted by a sapling in a garden centre, spare a thought about how long it may be there!

Shrubs

The definition of a shrub: “a woody plant which is smaller than a tree and has several main stems arising at or near the ground.”

In reality, there’s not a clear dividing line between trees and shrubs – some large shrubs, such as Viburnum tinus or Photinia Red Robin can be grown as small trees with some judicious pruning to create a clean ‘trunk’.

Also, fast-growing tree Eucalyptus gunnii is often grown as a shrub, pruned hard to encourage the young, bluish round leaves.

Herbaceous perennials

‘Ones that come back every year,’ is how my mam refers to herbaceous perennials.  The top foliage dies back to the crowns in late autumn, the plant becoming dormant during winter, only to sprout again in spring.

Herbaceous perennials generally have soft or succulent stems, compared to the woody stems of shrubs.

These plants are your paintbox and the flesh on the bones of the trees and shrubs, providing colour from late spring to the frosts – Rudbeckia, Echinacea, Echinops, Phlox, Heuchera… the list goes on and on.

A good garden depends on a blend of all three (and annuals) for interest all year round.