Quick facts
Nurseries, ours included, put what is performing at the front. That is honest, but it introduces a bias: in April you are surrounded by plants that peak in April. Buy that way for three seasons and you own a garden magnificent in May and empty from August.
Form is the silhouette: the shape a plant makes against the sky once leaves and flowers have gone. Upright, arching, mounded, spreading, columnar, horizontal. It is the most permanent thing about a plant and the least examined.
Look at it sideways and squint until the detail disappears. What shape is left, and does your garden need it? Most gardens are short of vertical accents and strong horizontals, and long on rounded blobs. If the answer is another blob, put it down. Form is what carries a garden from November to March.
Foliage is on duty for ten months and flowers for perhaps two, so the leaf deserves more attention than it gets. Judge size, shape, texture and colour, including the underside, often the more interesting side. Bold leaves anchor a scheme; fine leaves make air and distance. Some that earn their keep:
Run your hand over the leaf. Texture is a real design tool and you can only assess it by touch.
Ask what month this plant is for, then what your garden is already doing that month. The useful purchase is almost never the thing flowering on the bench. It is the thing that will do something in February, August or November.
February wants scent and early bulbs. August is when most Irish gardens fall apart. November wants berries, bark, seedheads and evergreen structure. If you only buy in spring you will only ever buy for spring.
This sounds sentimental and is entirely practical. Plants we have a story about are the plants we look after.
A cutting from your mother's garden, the tree you saw at Altamont and could not stop thinking about, the fuchsia in every ditch on the road to school. Those get watered in a dry June. The anonymous gap-filler does not. So once form, leaf and season are satisfied, ask whether there is any reason this plant should be yours.
The four questions decide whether you want the plant. These decide whether it will live.
Every principle can be broken if you understand it well enough to know what you are doing. Breaking right plant, right place just costs money.
Once the four questions have given you a shortlist, two habits are worth carrying to the nursery bench.
The physical checks — roots, stem base, compost surface, pests — are worth thirty seconds on every purchase, and we set them out in full in Pot-grown, bare-root or root-balled?
Common mistakes
Bring a photograph of the gap you are filling and the team here will work through these questions with you.
First and foremost, you will need to consider the quantity of plants required to achieve a full looking hedge. We usually recommend 2.5 plants per linear metre for a fully mature hedge. For a semi mature hedge, you can plant 2 plants per metre.
However, different types of hedging plants have different growth habits, so the quantities of plants you may need could vary. it is always best to check with your local nursery.
