This week and next are a small plant special on the plants most of us walk straight past: ground cover. The low, tough, unflashy plants that knit across the soil and quietly do a job nothing else in the garden will do. This week is shade. Next Monday is sun.

"To me the meanest flower that blows can give Thoughts that do often lie too deep for tears."

— William Wordsworth, Ode: Intimations of Immortality

Ground Cover, Part One: Shade (8 min read)

Hello friends, Gary Stewart here.

There is a strip of ground at the front of our house, along the foot of the yew hedge, that I have been ignoring for longer than I would like to admit. I stood looking at it on Saturday afternoon after the pots were finally up off the ground (all but one; I have run out of feet), and for the first time in a while I really looked.

It is bare. Not freshly dug bare, the way a bed looks in spring when it is waiting for something. Bare the way ground goes when nothing has wanted to live there for years. The soil is pale and dusty on top, scattered with old needles from the hedge, and when I pushed a finger into it, it was dry a good way down, even after the rain we have had this month. Above it the yew goes up dark and solid, and between them they make a place that gets very little sun and almost no water.

I have walked past it to the front door every day for years. I have weeded it occasionally, when the weeds became embarrassing. I have never once planted anything in it.

The article I read and didn't act on

What makes this a little worse is that I know better, or at least I was told.

Years ago, when I was hunting for plant ideas, I came across an article in a gardening magazine about ground cover. I don't remember the magazine or the writer. I remember the argument, because it changed how I looked at gardens. Until then I had thought of ground cover as the plants you put in when you couldn't think of anything better: municipal, a bit dull, the green carpet under the shrubs in a supermarket car park. The article said the opposite. It said these were some of the hardest-working plants a gardener could grow; that they would go where nothing else would, cover the soil, shade out the weeds, and ask almost nothing in return. It said the gaps in a garden are rarely empty for long, and that you can choose what fills them or let the weeds choose for you.

I agreed with every word. Then I went and bought something tall and flowering instead.

I think most of us do this. We buy plants at eye level. We are drawn to height and colour and the thing in flower on the bench by the till, and the plants that would do the most good sit low in their pots at the back, looking like nothing in particular. Ground cover is not chosen because it is beautiful, although much of it is. It is chosen because it is useful, and usefulness is hard to see from the garden centre aisle.

What the summer showed me

This summer's dry spell made the argument better than the article ever did.

Wherever I had soil left bare, it suffered. On clay, bare ground in a drought bakes hard on the surface and then cracks, sometimes wide enough to lose a trowel in. Water that does fall hits the crust and runs off instead of soaking in. Weed seeds blow into the cracks and wait. When the rain finally comes, it hammers the surface and seals it again.

Wherever something was growing low across the soil, it was a different story. The ground underneath stayed cooler and kept a little more moisture, because the leaves were shading it from the sun and the wind. The surface stayed open, so the rain could get in. And there were fewer weeds, because there was simply less room for them.

That is all ground cover really is. A living mulch: a layer of leaves that does what a barrow-load of compost does, except that it does it every year, without being asked, and only gets better at it with time.

I knew this. I had read it. It took a summer of cracked borders and a bare strip under the yew to make me feel it.

The hardest ground in the garden

Dry shade is the spot every gardening book warns you about, and the foot of a yew hedge is about as dry and shady as it gets. The hedge throws heavy shade all year. Its roots form a dense mat just below the surface and take whatever water arrives. The canopy acts like an umbrella, so much of the rain never reaches the ground at all. Most plants put in there struggle for a season and then quietly give up.

But not all of them, and that is the point of this week.

There is a small group of plants that has evolved for exactly this: the floors of woodland, under trees and among roots, where the light is low and the water is taken by something bigger. They have learned to grow slowly, hold on, and spread a little further each year. They will never be the loudest thing in the garden. But they will be there in February, green and low and holding the ground, when the showier plants are dead stems or nothing at all.

I already grow one of them, and it is where I want to start.

The one I already trust

I have epimediums in the garden, and I would recommend them to anyone with shade. They are the plants I wish I had read about first.

Through the winter they hold their leaves, heart-shaped and often tinged bronze or red as the cold comes on. In late winter you cut the old foliage to the ground, which feels brutal, and a few weeks later delicate sprays of small flowers appear on wiry stems, shaped like tiny bishops' hats or spurred little stars, followed by fresh new leaves. Then they spend the rest of the year knitting the soil together beneath them with slow, creeping roots.

They are not quick. An epimedium takes a couple of years to settle, and for that time you will wonder whether it is doing anything at all. It is, underneath. Once it has its roots down, it is one of the toughest plants I know: it will put up with dry shade, roots, and neglect, and still look tidy at the end of it.

I keep coming back to that patience. Most of what is worth having in a garden is doing its work long before it shows.

What I am planting under the yew

The rain forecast for Tuesday, and again on Saturday, makes this a good week to plant. Autumn is the best time of year to put ground cover into dry shade, and possibly the only good time. The soil is still a little warm, the rain is starting to return, and a plant has the whole winter to get its roots out before the hedge takes the water again next summer.

My plan for the strip is not complicated. More epimedium, plus a few of the plants in the profiles below, bought small. Small plants establish far better among tree and hedge roots than big ones, because they fit into the gaps without too much digging and adapt to the conditions as they grow. I will dig each hole generously, work in some compost or leaf mould to give them a start in that dusty soil, plant them closer together than the label suggests so they knit up sooner, water them in well, and mulch around them. Then the important part: I will keep watering through their first spring and summer, because under a yew the rain cannot be trusted to do it.

After that, they are on their own, and that is what they are good at.

I will tell you how it goes. If it works, that strip will be the least interesting part of the garden in a couple of years, and I will be very pleased about it.

Epimedium (barrenwort, bishop's hat) Best for: dry shade, under trees and hedges, among roots

The one I already grow, and the first I would recommend. Evergreen and semi-evergreen types hold their leaves all winter, often colouring bronze or red. Delicate spring flowers in yellow, white, pink or orange. Slow to settle but extremely tough once established, and happy on clay. Cut the old leaves down in late winter, before the flower stems appear, so the flowers are not hidden. For the driest spots, the tougher yellow-flowered forms are the most reliable.

The honest drawback: slow. Expect two years before it really covers the ground.

Geranium macrorrhizum (rock cranesbill) Best for: dry shade, clay, awkward corners

If I could only plant one thing under the yew, it might be this. Soft, scented leaves form a dense mat that weeds struggle to get through, with pink, magenta or white flowers in early summer. Many of the leaves turn red and orange in autumn and hang on through the winter. It copes with dry shade, clay, and neglect, and it is easy to split and spread around once you have one plant.

The honest drawback: not the most refined flower, and it can look a little tired by late summer.

Euphorbia amygdaloides var. robbiae (Mrs Robb's bonnet) Best for: the very driest, darkest spots where nothing else will grow

Glossy, dark evergreen rosettes and acid-green flower heads in spring that glow in the shade. One of the few plants that genuinely thrives in deep, dry shade, spreading by underground runners to cover a patch quite quickly. Wear gloves when handling it or cutting it back: like all euphorbias, its milky sap irritates the skin and eyes.

The honest drawback: it spreads, and in better soil it can be more than you bargained for. Give it the hard spots and it will behave.

Lamium maculatum 'White Nancy' (spotted dead-nettle) Best for: lightening a dark corner

Silver leaves edged in green and small white flowers through late spring and summer. It lights up shade the way pale grasses hold the last of the evening light, and from a window on a dull winter day it is one of the few things that still reads as bright. Semi-evergreen and quick to spread. It does better with a little moisture, so add some compost when planting in dry spots.

The honest drawback: it can thin out in very dry, rooty ground. Better at the edge of the dry shade than right under the hedge.

Cyclamen hederifolium (ivy-leaved cyclamen) Best for: directly under trees and hedges, where the roots are thickest

Small pink or white flowers that appear in late summer and early autumn, often before the leaves, followed by silver-marbled foliage that covers the ground all winter and dies away in summer, exactly when the ground is at its driest. Made for the foot of a hedge. Buy plants growing in pots rather than dry tubers; they establish far more reliably. Plant shallowly, with the top of the tuber just below the surface.

The honest drawback: it disappears completely in summer, so mark where it is before you dig.

Next Monday: Ground Cover, Part Two: Sun. Including the alchemilla that runs along the edge of one of my borders, and what it taught me about letting a plant do its job.

Gary Stewart writes every week from a small garden on Norfolk clay.

No expertise, no ideal garden, just what the soil taught him that week.

Written slowly, at the speed of the garden, for people who read every word.