GARDENING / Something blooms in sub-Sissinghurst: Mary Keen's garden season by season: Summer

NOW IS the summer of my discontent as I visit other people's gardens and envy their maturity. In the first season of any planting you have to accept that everything is off balance. Roses that should be 6ft tall are not much higher than a bucket: but hardy geraniums and alchemilla, the plants that are meant to be the low-key background for the finer flowers, are the tallest colours for yards.

When Prince Puckler Muskau toured England in the 1830s, he admired plants in a sea of soil, growing so that they did not touch one another. He would have liked it here more than in the best gardens of our time where, by midsummer, you cannot see a speck of earth.

I went to a favourite place in Dorset last week and admired tiers of flowers in misty hues. Coming home to sub-Sissinghurst, where each plant is an island, marooned in mushroom compost, browned-off was how I felt.

The drainage, or lack of it, is partly to blame. The four beds that fill this flower garden were made in the wet spring; I knew conditions were less than ideal, but it seemed worth having a go. Two of them are fine, but one has been issued with a health and safety warning since a crambe was discovered with root rot and had to be thrown away. I'm telling myself that the problem will be cured by constant working of the soil. I hope it will.

Some experts say that too much digging can be a bad thing with compacted soil, because it locks you into forking it over for ever more. The structure, they imply, is permanently damaged. I must admit, there is a sort of silent spring atmosphere: no worms wriggle, no weeds appear like cress. If the experts are right and the worst comes to the utter worst, the winter will have to be a time for digging drainage trenches across the wetlands.

I recognise that this is not something which is going to be solved in a summer, especially one as rainy as this has been. But we emptied one of the two unhappy beds and dug it over to a depth of two squelchy spades. The damp rocks in the brush were harrowed away and plenty of grit to improve the drainage went into the soil. Since the radical dig, we have forked it over three times between monsoons, layered it with mushroom compost like a lardy cake and put in some expendable plants.

The second bed was not as bad, but it did have more than its quota of wet rocks, varying in size from grapefruit to melon. Plum-sized ones are acceptable. In both beds, the roses are having a struggle. They and deep-rooted plants such as the crambe must at some point have been in contact with standing water, which is hateful to a plant as it deprives the roots of oxygen. But shallow rooters - such as the giant silver thistle sidalceas, and hardy geraniums - seem to cope.

I could major in plants such as Silene acaulis, a Balkans native that likes to be damp, and Salvia uliginosa, the bog sage - but this is the Cotswolds, for goodness sake, where limestone drains free and verbascums thrive. We are 60 feet above the stream at the bottom of the valley, so the water ought to run down the hill. I refuse to believe that this is any more than a little local difficulty, caused by too much earth-moving in a wet spring.

Because of the conditions, perhaps it is just as well that meanness prevailed on shopping trips to nurseries. I bought one of each plant, not the way to an instant garden. For other people I would never do this; their orders for perennials come in battalions, because clients expect results. But if I were buying for clients, I would probably not have bought the double white sweet rocket, which is famous for packing up after a summer, or various named campanulas which I hope to increase here. At pounds 3.50 a plant for this sort of rarity - which never comes true from seed - you have to be very rich to invest in clumps of a dozen or more. But the survivors can be increased by division or by cuttings.

Sometimes new plants can be split straight away, like the particularly good form of Nepeta 'Six Hills Giant' that came from a new favourite nursery. This seems to be a better blue than the specimen bought from another source. The point of named forms is that they are supposed to be exactly what they say they are, but I suspect that many nurseries are growing plants like this catmint from seed rather than from cuttings. They look roughly like what you expect to get, but if you compare them with the better form, they are simply not the same. The moral is: stick to nurseries where growers know the difference and take a pride in growing only the best.

The champion growers tend to be in far-flung places, which means that precious gardening time has to be spent plant hunting. My own favourites include Carol Klein, of Umberleigh, Devon, and Sandra Bond in Hoxne, Suffolk, who both do mail order in winter only. John Coke in Bentley, Hampshire, and the Arbuthnotts of Kidderminster (see addresses below) are two more wonderful sources of good plants, but neither will post. Bernwode Plants in Buckinghamshire, however, has stolen a march on the rest by pioneering a year-round delivery service for specialist plants. Hooray. Send them pounds 1 for their catalogue of 1,500 plants.

A rare flower, which was not the result of a trip to a nursery, appeared quite unexpectedly at midsummer. When we moved, gardening friends were generous with presents; among those that arrived in a pot for the greenhouse was a cactus that had lost its label. As cacti are not the plants I most admire, I may have been less than loving towards it. If I thought about it at all, I expected it to turn into the Christmas cactus, which has purple fleshy flowers at the end of its swollen prickles.

When a bulbous yellow growth appeared, it confirmed all my prejudices. Then, one evening, I found the swelling had opened into a giant sort of water lily, wafting a powerful scent. There among the geraniums was the plant that the Victorians travelled miles to see in bloom. The 'night-blowing' cereus was growing in a six-inch pot on a shelf in the porch.

Selenicereus is, the books say, easy to grow in acid porous compost. It is an extraordinary, sinister thing, and the single nine-inch flower lasted for only three days. I suppose I must be kinder to it now, but I doubt it will flower so well as when it was neglected.

Carol Klein, Glebe Cottage Plants, Pixie Lane, Warkleigh, Umberleigh, Devon EX37 9DH (0769 540554). Sandra Bond, Goldbrook Plants, Hoxne, Eye, Suffolk IP21 5AN (0379 75770). John Coke, Green Farm Plants, Bentley, Farnham, Hampshire GU10 5JX (0420 23202). The Arbuthnotts, Stone House Cottage Nurseries, Stone, Kidderminster, Hereford and Worcester DY10 4BG (0562 69902). Bernwode Plants, The Thatched Cottage, Duck Lane, Ludgershall, Aylesbury, Buckinghamshire HP18 9NZ (0844 237415, evenings only).