Border line: Dismantling a garage in Anna Pavord's garden meant space for a shrub border

If we hadn't pulled down the garage, I wouldn't have made the shrub border. This is the Law of Unintended Consequences. And it's how most of us go on in our gardens. Things get done in a piecemeal way. The garage was the first thing you saw when you turned into our yard and it blocked out the view beyond. From the beginning we planned to get rid of this breezeblock barrack, so the ground swept uninterrupted from the yard down to the valley below.

The bank behind the garage had been a useful tip for the builders. But at the far end was a superb Viburnum tomentosum spreading flat layers of branches over the bank. Beneath the unappetising top-dressing, there was obviously some proper earth. And the bank, though partly shaded by trees, faced south.

The bit of the place I think of as "the garden" lies across the yard in the opposite direction from this bank. But when we demolished the garage, we left the concrete floor in place as a parking pad. From here, visitors looked down onto the churning mass of rubble and ground elder, garnished in season with nettle and Japanese knotweed.

I began to tire of the jocular, "Call yourself a gardener?" remarks. So, over the past four years, we've been clearing and planting up the area and now the whole 10-metre stretch is almost finished. "Clearing" is such an easy word to write. But anyone who has taken on an abandoned bit of ground knows what it entails: endless, time-consuming trips to the tip. On a bank as steep as this one, you don't want to disturb the earth much. Deep digging was out of the question.

So was gardening, in the non-stop, tinkering-around sense that gardening with perennials implies. Shrubs need attention, of course, but not much and not all the time. Shrubs have been rather forgotten in the obsession with prairie planting, perennials and flowering meadows that has been a feature of the past few years. But they provide splendid anchors for more ephemeral planting. And a long season of flowering.

The bank was too big a piece of ground to clear and plant all in one go. And we decided that, if this was going to be a place to be looked at, we might as well make a path along the bottom of the slope so we could look up at the plants, as well as down on them from the yard. The first shrub to go in was a dogwood – Cornus mas – which opens the flowering season in February. Now that the planting is almost complete, there is something in flower on the bank all the way through from this early dogwood to Heptacodium miconioides, which does its thing in September and October.

Its late flowering was the chief reason I got the heptacodium. That, and the fact I'd never heard of it. Does it earn its keep? Well, it's an interesting shrub, vigorous, quite upright in habit with pale bark that peels away leaving an even paler layer underneath. Interesting in this context means that if I hadn't already got mahonia in the garden to provide late flowers and scent (and the hippery to provide late fruits and autumn colour), there's no way I'd reach for heptacodium. The whorled white flowers are fine but in a kind of stamp-collecting way – meaning there's nothing that exactly matches them. Heptacodium stands on its own. H. miconioides is the only kind there is. I like its leaves, which have three deeply-incised veins running from stem to tip. Few leaves have that particular vein structure... but you can tell by now that I'm desperately trying to justify having spent £12.50 on this thing. Let's move on.

The new path leading along the bottom of the bank gave us the opportunity to use a few smaller shrubs in the foreground, where they would not be overwhelmed by the bigger stuff behind. I put in Magnolia stellata, which of course won't stay small. But it takes a long time getting big and even when it is, it won't be in the way. Already, in this season, you can gloat over the fat furriness of the buds that will open into white, strap-petalled flowers next March or April.

This summer I added Callicarpa bodinieri to the front line of the shrub border. From late August onwards, it bears extraordinary clusters of purple berries as unreal and as shiny as ceramic beads. Before they fall, the leaves, too, turn dull shades of pinkish purple, but they can't compete with the berries. The shrub looks its best after the leaves have fallen, when only the fruit is left, clustering on the bare grey stems. And in the tree-peony madness that seized me earlier this year, I also planted 'Koshino-yuki', as much for the bronze beauty of the young foliage as for the outrageous May flowers.

The elegance of the existing viburnum, a huge old beast that spreads over at least five metres, persuaded me to add another, V. opulus, the guelder rose. It flowers a little later than V. plicatum which is usually at its best in May and early June. Both have creamy flowers made like a lacecap hydrangea's, but V. opulus has the bonus of gorgeous translucent fruit, like bunches of enormous redcurrants, that hang from the branches well into winter.

Lacecap hydrangeas ('White Wave' and 'Grant's Choice') take care of the second half of summer, though I'm still searching for the one I remember from my parents' garden which had showy white outer florets surrounding a centre of dense, almost electric blue. But of all the new arrivals in the shrub border, my favourite is the pearl bush, Exochorda x macrantha 'The Bride'. It is ludicrously generous with its white flowers in May and (which is even better) its branches arch out and down in a way that exactly suits the sloping contours of the bank.