Quick facts
Think about the gardens that have stayed with you. Almost none of them stayed with you because of a flower. It was the shape of things, the weight and lightness, the way one leaf stood against another. Flowers are the event; foliage is the room it happens in.
This matters more in Ireland than in drier countries. Our growing season is long and our light is low and grey for much of it. A planting built on flower colour alone spends nine months looking like an unmade bed; one built on leaf structure looks composed in February drizzle and again in October. So when you are standing in a nursery with a plant in your hand, ask what it looks like in July with nothing on it. If the answer is "not much", it needs to earn its place some other way.
Handle the foliage rather than reading the label. Four questions, in this order.
Leaf size sets scale. Big leaves — Fatsia japonica, Rodgersia aesculifolia, the larger Hostas such as 'Sum and Substance' — make a small garden feel larger, not smaller, because they give the eye something definite to measure against. Fine foliage recedes and softens. Most amateur plantings are all medium: a fog of leaves at one size, which is why they look busy and flat at once.
Shape is the outline. Phormium tenax is a fistful of vertical straps. Hakonechloa macra is a cascade of horizontal ribbons. Dryopteris filix-mas is a shuttlecock of dissected fronds. Three plants, three different gestures — that is what you are buying.
Green is not one colour. There is the blue-green of Hosta sieboldiana, the black-green of yew, the grey-white of Stachys byzantina. Then the departures: the bronze and plum of Heuchera, the glaucous blue of Melianthus major.
Texture is what the leaf does with light. Matt foliage absorbs it; glossy foliage throws it back. In a dull Irish winter a glossy evergreen such as Fatsia or Griselinia is doing real work, bouncing what light there is around a dark corner.
Contrast is how a planting holds the eye and rests it at the same time.
The reliable pairings, all of them proven in Irish gardens:
Two working principles. Contrast is loudest at the boundary, so place a contrasting pair touching, not three metres apart. And keep the leaf shapes in one bed to four or five, repeated — more and the contrast cancels itself out.
A garden of nothing but green can be the most restful place you own. Stop asking green to be a background and you start seeing how many greens there are: the near-black of Taxus baccata, the yellow-green of Milium effusum 'Aureum', the sea-grey of Astelia.
Build a green planting as you would a monochrome photograph — by tone. Darkest greens at the back and in shade, the lightest where you want the eye to land, texture carrying the interest colour normally would. It is why the woodland at Altamont holds up in November, with nothing in flower.
Variegated foliage is genuinely useful in shade: it does the job of a flower without needing sun. Used badly, it fidgets.
Three habits keep it honest. Use one variegated plant per view, not five. Prefer the calm variegations — clean white or cream margins, as on Brunnera macrophylla 'Jack Frost' — over speckled and splashed ones, which read as disease at a distance. And repeat the same variegated plant rather than collecting different ones; repetition turns a novelty into a rhythm. We grow much of our foliage stock outdoors rather than under glass, because leaf colour and substance both hold better on a plant that has felt some wind.
Common mistakes
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.
