Gardening: A spot of pot training

Never mind the plants, what about the troughs, compost, fertilisers and more ... Ursula Buchan advises on how to plan the patio for the best summer display

As if driven by some communal atavistic urge, gardeners in late spring rush to empty every pot and tub in the garden (whether their contents are still flowering or not) and replace them with summer flowers. It would appear that, by early May, we cannot wait to be rid of all those fresh yellows, blues and acid greens, in favour of the warmer, richer colours of high summer. Hardiness no longer seems the cardinal virtue it was in February, now that the frosts seem to be over for good.

Everything conspires to egg us on. Garden centres, nurseries, florists, even supermarkets and garage forecourts, are full to bursting now with "summer bedding" or "patio" plants, those frost-tender annuals and perennials which are naturally suited to, or have been expensively bred for, pot culture. They come into flower quickly, once planted, and go on flowering in hectic profusion until late summer and sometimes until the autumn frosts.

Garden centres are so geared up to container gardening that all the kit that you need (pots, compost, fertilisers and planting combinations) are provided, thus removing the last vestige of anxiety. You have nothing to lose but the contents of your wallet, and everything, by way of a gaily colourful patio, to gain.

Cassandra that I am, I cannot refrain from one or two mild warnings. If you heed them, you may make your own pot luck. To begin with, there is no rush about this. Even now, it is unlikely that most gardeners (especially in country areas) have seen the last frosts. Anyone who lives in a cold district will have to put their planted containers under cover - at least at first. Everyone else would be well advised to leave them somewhere sheltered in the garden for a week or two, bringing them under cover (a porch, outhouse, cold frame, unheated greenhouse, even the front hall) when a cold night is forecast.

That way, there is less risk of damage to those tender annuals such as tobacco plants (nicotiana), which have big, fleshy leaves and often benefit from a bit more hardening off before encountering the rigours of the open garden. After all, most plants are protected by some kind of structure, usually glass, when you buy them.

If you are not experienced in the arts of patio gardening, the first things you need to buy are pots. I am afraid that there is simply no substitute for spending good money on them. The nicest (and, incidentally, most substantial and stable) are, generally, the most expensive. To take liberties with an old head-gardener's saying: "A penny for the plant, a pound for the plant-container"

The choice of what to plant, and how many of them, requires some thought, and time spent on research is not wasted. However, garden centres usually have people on hand to advise, and the optimum spacing of plants in containers should appear on the large bench label, even if not always on the smaller pot labels. A notebook is invaluable.

It is always tempting to buy plants already in flower. But a flowering "plug" plant in a small tray is a vegetable cry for help. Faced with possible extinction from lack of food or water, its response is to flower and seed in a hurry. Buy the dull-looking, green-leaved ones where you can.

You will need to buy a reputable multi-purpose potting compost based on a peat substitute, such as composted wood bark, in which to put the plants for their five-month sojourn. This year, for the first time, you also have the choice of buying one that contains a systematic and contact insecticide called Intercept. Levington's Plant Protection Compost is more expensive than conventional ones (pounds 5.99 to pounds 6.49 for 50 litres), and has not yet received Ministry clearance for edible plants (so no good for herbs, or patio strawberries) but it offers control of aphids for three months, and of fungus gnats and vine weevils for 12 months.

If you choose a conventional compost, it is worth considering water-retaining polyacrylamide granules, such as Swellgel, to add to it; if mixed thoroughly with the compost, which is then watered well before the plants are put in, they should allow greater intervals between waterings. I also recommend a "controlled-release" fertiliser such as Osmocote Plus tablets, to put on the surface of the compost after planting. The resin coats of these aggregated granules gradually disintegrate, releasing balanced fertiliser steadily, over five or six months. They work fastest in warm conditions, when the plant will be growing most actively. Chempak's Food and Drink and Growcroft's Basketmate offer an ingenious and labour-saving mix of water-retaining and fertiliser granules.

The advantage of these technological innovations is that, provided that the manufacturers' instructions are followed, modern pot culture now makes falling off a log look like a frighteningly complex operation. It is displaying pots to their full advantage which can prove tricky.

But that's another story.