Late in the day: How to make your gardening interesting in August

Already by the end of June, I felt that the best things in the garden had already happened. Now, at the end of July, I know they have. August has always seemed a black hole in our patch. Partly, this may be because in August I've always been somewhere else. All the summers of my childhood were spent in Pembrokeshire. Then for 15 years, we took our own children there too, Augusts of anoraks and Wellington boots, damp bonfires and Atlantic breakers. Now that their memories have dried out a bit, they talk fondly about those holidays. But they take their own children to sunny Portugal. Free of school holidays, I go to Scotland in August and collect waterfalls.

Of course there are plenty of ways to keep a garden singing in August. Dahlias for a start. But we did dahlias a long time ago and now I've turned against their beefy arrogance. There are also plenty of perennials that peak in the second half of the summer (read Marina Christopher's excellent book Late Summer Flowers) but most of the things I'm passionate about – iris, tulips, ferns, euphorbias – have done their thing. Ferns and euphorbias still look handsome, but not as ravishing as they did in May. Of the three kinds of herbaceous plant I reach for more often than any other – euphorbias, thalictrums, and monkshoods – only the monkshoods have yet to peak.

The first thing you are generally told about monkshoods is that they are poisonous. Yes, they are, but who'd ever think of eating them? For a gardener, the most important thing about them is that they have superb, dark, deeply-cut foliage and splendid spikes of hooded flowers, mostly in shades of blue. There's a white kind, 'Ivorine', and a greyish variety, 'Stainless Steel', but neither has the punch of the blue. Monkshoods will easily grow up to 1.5m (5ft) but, unlike delphiniums, don't need staking.

The kind I like are mostly tall and a dark, saturated kind of blue. 'Newry Blue', bred at the Daisy Hill nursery in Northern Ireland, has been around since the Fifties, but is an outstanding monkshood which flowers all the way through from July to September. Aconitum carmichaelii 'Kelmscott' is equally tall (1.5m) and late. 'Arendsii' doesn't even start until September and continues until, in our garden, the leaves on the hazel behind it turn the colour of butter.

When we first came to our new house, I had The Plan, to combat the late-summer doldrums. I would grow lilies and I would make a more serious attempt to grow decent annuals. I've done both, but this season, for different reasons, neither has solved the August gap. Lilies grow beautifully in the light, nutritious, slightly acid soil we've got here, but the more I plant, the more lily beetle we attract. There's a logic in that I suppose, but where are the wretched things coming from? For decades, there was not a single lily on this patch of ground. As soon as I started to plant them, they appeared. This year, perhaps because the lilies came through earlier than usual, they were sitting provocatively on the leaves by mid-April. I've been on the warpath ever since.

And actually, my favourite lilies flower in June and July, not August. By late June, both 'Nicotine' and 'Red Russian' had finished their display. They are types of martagon lily, with smallish reflexed flowers beautifully held on a stem about 45cm (18in) tall. The ordinary martagons (a deep, raspberryish kind of pink) grow well here and I'm hoping the newly introduced hybrids will, too. 'Nicotine' is a burnt marmalade colour. 'Red Russian' is the deepest maroon you can imagine. Both have brilliant orange stamens hanging out like bell clappers from the mouth of the flower. They are wonderful. But finished. As are the Regale lilies and 'Casa Blanca', which in July filled the terrace in front of the house with its astonishing scent.

As for the annuals, The Plan started well. In September last year, I sowed seed of cornflower, ammi and orlaya (think cow parsley, but slightly grander). This is by far the best way to get substantial plants to set out in spring. In early autumn, I pricked out each seedling into its own 7cm (3in) pot and then later in autumn, repotted everything into slightly larger (11cm/4in) pots. They spent the winter in the greenhouse – unheated. By mid-March this year, they were roaring to get out of their pots, so I took a chance and planted them out. As we all now know, we had the warmest spring since records began. The plants grew magnificently. The cornflowers produced masses of flower buds on sturdy fat bushes at least 129cm (4ft) tall. The ammi and orlaya got up to 2m (6ft) with lots of useful side branches.

This spring I sowed a different clutch of annuals: Ammi visnaga, with beautiful pale-green domes of flower, green-flowered tobacco plants, English marigolds, a white-flowered cleome called 'Helen Campbell'. They, too, were individually pricked out and potted on, but by the time I wanted to plant them out, the soil had baked hard enough to bend a trowel and there had been no rain since March. Those annuals had only one desire – to race straight up to seed, without pausing to bush out on the way.

But the September-sown plants looked superb, until on Sunday 12 June, we finally got rain, almost two inches of it, the first proper rain for more than three months. So that was good. Or would have been if it hadn't arrived on the back of a wild gale. Foxgloves, cornflowers, ammi, orlaya all collapsed on top of their shorter neighbours, which snapped under the weight. The orlaya and ammi had bamboo stakes, but evidently the weight of rain on plants that size was too much and the stakes fell over with the plants. I tried to pull them back into shape, but that never works. Before the collapse, the orlaya and ammi had begun to interlace in an enchanting way. But on the ground, that interlacing translates into snapped side branches. Propped up again, the plants look like patients in neck braces. All now rests on the cleome. And a late batch of English marigolds, 'Touch of Red', which I planted out towards the end of June. Never mind. By September, I'll be deep in bulb catalogues again, planning for 2012. Which of course will be disaster-free...