Flights of fancy: What are the best plants for the tricky month ahead?

There's no need to rush, says our resident gardener – there's some pretty impressive bird watching to be had first…

Rooks, Anna's favourite birds, taking flight at sunset (Alamy)

We're now facing what is still, for me, the most difficult month in the garden, in terms of keeping up the show. But I'm getting better at accepting that perhaps nothing too much should be expected of the gardener in late July and August. A little dead-heading perhaps, a little work with the watering can and lots of looking from deckchair or hammock. As gardeners, we tend mostly to concentrate on one small task in one small place. Now there's an opportunity to think about the bigger picture.

At least that's what I tell myself when I move out with a cup of coffee to the creaking cane armchair set in front of the house. But instead of thinking about new possibilities for the front borders (once again, they are romping through summer packed with nasturtiums) my interest drifts off to the ways different birds fly.

Occasionally you can hear the flight, the thwacking whistle of air passing over the ravens' wings, the thrilling, measured beat of geese or swans flying in a V-formation over the valley. That doesn't happen often, but when it does, I always run out to watch them. I wave. And I always long to be with them. You can hear the pheasants taking flight too, but that's an irritating, clattering noise. Basically, they are ground birds. They'd much prefer to run along the ground and hide in a bush than take to the air. Sometimes, if they've been forced to take off from high ground, they'll go into a long, downhill glide which is good to watch, but to me they will always be interlopers. Awkward birds, though very pleased with themselves.

The swallows are brilliant flyers – fast, energetic, acrobatic. They have a lot to do in a short time. With us, they are nesting in a woodshed with a stable door. The top half of the door happened to be open when they were casting about the garden, wondering whether to stay. And having investigated the woodshed, they evidently decided it would do.

I have to walk past the shed quite often, but am never prepared for the way the birds zoom out right in front of my face. How can they get up such speed in such a short time? Just occasionally one rests on the television aerial on top of the house chimney and twitters madly in a constant, high pitch. Swifts scream and fly all at the same time. Swallows aren't so piercing. Last week there were four in the air together, so I assume that, despite the appalling weather earlier this month, they managed to feed their young.

The best birds to watch are the buzzards and the rooks; the rooks in small determined posses harrying the buzzards, the buzzards sliding sideways down the wind, not intimidated, but temporarily ceding the airspace, knowing they can return. From the terrace, with the land dropping away steeply and plenty of sky ahead, it's like watching a film of the Battle of Britain. The rooks, of course, are the Spitfires, the buzzards the slower, less agile German bombers.

Less agile? I wonder whether that's quite right. The buzzards are fabulous to watch, slowly working their way up through the thermals in big sweeping circles over the valley. They seem to spend an extraordinary amount of time in the air, compared with the other birds that live here, but they rarely flap their wings. A favourite perch is a big oak with a section of dead branches. One or other buzzard flaps away from that every now and again. Otherwise they wheel silently, wing tips curved up in an entirely distinctive way. When we first came to Dorset, they were relatively rare. Not now. The past couple of months have been full of the complaining mew-mew of a young buzzard, forced to find his own food.

The rooks are my favourites. They nest in the alders that drift down the stream in the valley below, so their activities are, for me on the terrace, almost at eye level. They seem to have a vocabulary bigger than any otherf bird around here. They are also intensely social and the rookery below has at least 60 nests. When they leave the alders, they fly fast and purposefully. But I don't understand their movements. Why, on a fine summer evening at a quarter past nine, will they suddenly rise up out of the trees and wheel round in the sky, hundreds of them, shouting at each other, not going anywhere, shaping and reshaping into fluid dark pools and streams against the sunset? And then descending back into the trees. During the night you rarely hear them, but they play a big part in the dawn chorus, that during the summer starts here at about quarter past four.

But this is exactly what I was saying about the cane chair and coffee. Instead of concentrating on plants to take you through August in style, I've drifted off into birds. So, before I get going on jays (a new arrival in our valley), I'm going to suggest six things that will provide excitement in an August garden. I'm biased, of course, towards plants that, though they may peak in this month to come, will also pay rent before and after high summer.

Monkshood (Aconitum carmichaelii, A. napellus and others) Hooded flowers in varying shades of blue from the steely grey of 'Stainless Steel' to the deep navy of 'Spark's Variety'. Held in strong, branching heads above dark, deeply divided foliage. Height from 90cm-1.5m, best in cool, moist shade.

Agapanthus A perennial that looks as though it ought to be a bulb, available in a vast number of selections, either white or blue. The broader the leaf, the more tender the variety. Big, rounded umbels of flower, like an allium's, growing from clumps of shiny, strap-shaped leaves. Height from 60cm-1.2m, best in well-drained ground in full sun.

Hydrangea (more specifically H. sargentiana) Handsome shrub with big sharkskin-textured leaves. During July the flower buds gather in knobby fists at the ends of the branches. By August they are fully open, the tiny lilac-coloured flowers in the centre surrounded by much showier florets. Height up to 3m and gaunt in habit, but happy in deep shade – a useful trait.

Salvia (of many, I'm choosing S. dombeyi) A Peruvian species, tender in Britain, but easy to propagate from cuttings, taken in autumn. Coarse, pointed leaves and astonishing flowers, said to be the biggest of all the salvias, carried in hanging racemes. They are pillar-box red, and emerge from purplish bracts. Height up to 3m, depending on the season. Does well in moist, but well-drained soil in full sun. Superb.

Selinum (Selinum wallichianum) Called "the queen of umbellifers" by the Edwardian gardener EA Bowles, who never handed out praise lightly. Like a giant cow parsley with very bright green, finely cut foliage from early in the year, and (eventually) flat white heads of flower. Height up to 1.5m, best in rich, moist soil, either in sun or part shade.

Stokesia (Stokesia laevis) In appearance, like a China aster, but perennial, with masses of big, many-petalled flowers, either in soft blue ('Blue Star') or a pale, sulphurous yellow ('Mary Gregory'). Height up to 60cm and said to be happiest in moist, slightly acid soils, but worth trying anywhere. Bees and butterflies love them.E