If it fails in successive seasons, think about drainage. This is the most potent cause of problems. Lilies hate damp lying round their roots. But they also hate drying out, which seems a contradiction in terms. The most successful groups in our garden grow on an old, well-cured ash heap, made long before we came here. The soil drains fast and is well-larded with small pieces of cinder, which makes it uncomfortable territory for slugs. By mulching it well with leaf mould, the underlying soil can be kept moist without gumming up the drainage.
I mention the ash heap, not because every garden should have one, but because it shows so clearly what lilies need. Heavy clay soils are the most difficult soils to convert to suitable des res. We all try to cheat on the boring work of excavating heavy land. But there is an answer. Abandon the land and grow lilies in pots instead. You can adjust the drainage easily, by adding sharp grit to the planting mix. There is another advantage, too. Some lilies, such as the 7ft-tall L pardalinum, the golden-rayed lily (L auratum), and the shade-loving L speciosum grow best in acid soil. You may have alkaline soil, but in a pot, you can give lilies all the acid they need by using a special ericaceous compost.
Most lilies prefer a soil that is just the acid side of neutral, but the beautiful L martagon, with turks cap flowers of brownish purple, prefers lime. Other popular lilies like the white-trumpeted Regale lily, yellow L pyrenaicum and L henryi are not fussy and will put up with whatever they are given.
As to position, lilies like their heads in sun (dappled or otherwise), but their feet in shade. In a pot, this is not easy to arrange. But if you choose a pot made out of a well-insulated material, such as wood or clay, you will keep the compost cooler than if you plant in a trendy galvanised metal bucket. Spread a layer of pebbles over the surface of the compost. This, too, will help to keep it cool and moist.
The best time to plant lilies is supposed to be late September, when flowering has finished, but the ground is still warm. Put into welcoming soil, lily bulbs will make roots and sort themselves out ready for the big push in spring. In practice, this is not usually possible. If I order lilies now from the bulb catalogues that have been arriving here in droves during summer, the bulbs will turn up in mid-November.
The difficulty in spring is that bulbs may have shrivelled away some of their health and vigour. Unlike daffodils, they have no outer protective coat, and you must buy them before they start sprouting. It is pathetic to see lily bulbs displayed in garden centre spring promotions: out of the boxes of wood shavings spurt forests of sickly white shoots. Desperately, they try to keep to the timetable that was devised for them by nature rather than some godforsaken marketing department.
Bulbs such as these are not good buys. A plant needs to concentrate on one thing at a time. Roots first, shoots after, when they can be sustained by the roots. Shoots springing from dry bulbs are living on capital and there is no future in that.
The famous nursery, Bloms, shows a few mouthwatering lilies, such as the white martagon (pounds 4.25 each) and the lime-loving, apricot-coloured L testaceum (pounds 9.25 each) in its autumn catalogue, but most ordinary garden kinds appear in its spring catalogue. I buy at both times, driven by whim. Both seasons have dangers, different but equal.
The shorter types of lily - up to about 4ft - look superb in tubs. By short, I do not mean dwarf. "Pixie" lilies (bred in the US) are loathsome things. They never get beyond 12-15ins and look squat, congested and ugly. "Little Rascal" ones are no better. Big tubs with 7-10 bulbs will give a better effect than three tiddlers with three bulbs in each. In small pots, lilies are more likely to dry out in summer and freeze in winter, neither of which is good for them.
Cover the bottom of the pot with broken crocks, gravel or chopped bracken. Add a layer of compost (coir compost did well in lily trials in the Northern Horticultural Society's garden at Harlow Carr, Yorkshire). Set the bulbs at least halfway down the container so they can be covered with 3-4ins of compost. If you plant in autumn, water the tub and keep it inside a cool shed until spring. If it is too big to move, cover it with a dustbin liner to keep out rain and cold. Once the lilies are above ground and growing strongly, they need regular feeding. I use Osmocote slow-release fertiliser, sprinkled on top of the pots in spring. Or you can use a liquid fertiliser, such as Miraclegro, once every two weeks.
Most lilies (except martagons) adapt well to life in pots, so there are difficult choices to be made. This is a good kind of difficulty: more than 250 different kinds of lily are listed in the current Plant Finder (Dorling Kindersley pounds 12.99). The sensible way would be to start with lilies awarded an AGM (Award of Garden Merit). That would cut the choice down to 23 and lead you to easy-to-grow varieties such as orange "Enchantment", the trumpet-shaped "Black Dragon" and the richly scented white lily "Casa Blanca".
But that group does not include "Citronella", which grows in a pot outside our front door. They have been there for 11 years. It is a graceful lily, with flowers held at right angles to the stem, yellow petals reflexed and freckled with black. On the other side of the door is a pot of "Yellow Blaze" lilies, whose flowers face up to the sky. That is not an improvement. Both kinds have excellent ginger-coloured anthers on long stamens, but whereas with "Citronella" you see these in profile, like lizards' tongues looping out to pick up flies, in an upright flowering lily such as "Yellow Blaze", the stamens are more circumspect, standing upright in a tight little bunch.
Scent is important. Some lilies are positively narcotic in the intensity of their perfume. In this respect the best I have grown are "Limelight" and "African Queen". Both are trumpet-shaped, the first a pale greenish yellow, the second, a chalky rich apricot with maroon washes on the petals' backs. Both are addictive.
Buy (mail order) lilies at: Jacques Amand, The Nurseries, Clamp Hill, Stanmore, Middx HA7 3JS (0181-427 3968); Bloms Bulbs Ltd, Primrose Nurseries, Melchbourne, Bedford MK44 1ZZ (01234 709099); Burncoose & South Down Nurseries, Gwennap, Redruth, Cornwall TR16 6BJ (01209 861112); De Jager & Sons, The Nurseries, Marden, Kent TN12 9BP (01622 831235).
Read `Kew Gardening Guides: Lilies' by Victoria Matthews (Collingridge pounds 8.95), `Lilies: Their Care and Cultivation' by Michael Jefferson-Brown (Cassell pounds 14.95).
Join The Lily Group of the Royal Horticultural Society, via Dr A F Hayward at Rosemary Cottage, Lowbands, Redmarley, Gloucester, Glos GL19 3NG (01452 840661)