Two viruses are causing the damage: tobacco mosaic virus and potato Y virus, both of them spread by sap-sucking aphids. The signs are unmistakable. Leaves look mottled and unhealthy, the mottling sometimes developing into dead patches. The edges of the leaves may curl inwards. The plant looks how you feel when you have flu.
Like flu, the virus is easily transmitted to other plants, such as tomatoes, as aphids move in their languid, maddening way from one devastated patch to the next source of sap. It can also be relayed by touch. If you dead- head infected surfinias and then move on to nip out side-shoots of tomatoes, you run the risk of contaminating them with the same problems.
Producers hope to have cleaned up their stock by next year. But what substitutes are available now? Elm House is suggesting a snapdragon called 'Chinese Lantern' which has the same cascading habit as the Surfinia petunias. That would not be my choice. Snapdragons do not have the-show- never-closes quality that we now expect of bedding plants in pots.
Trailers are important in pots. If you can see the edge of the container right the way round and the flowers all stand upright on top of it, it looks curiously as though the two elements are going to part company. Trailers and floppers which disguise the join between the two make the arrangement look comfortable.
This is why the foliage plant Helichrysum petiolare in either grey or lime-green is such a favourite in pots. It knits the composition together. It blurs edges. But it can be a swamper. Lotus berthelottii is finer and less ambitious. It cascades, in contrast to the helichrysum which whirls off in all directions like a puppy let off a leash.
For years, lotus was known only as a conservatory plant. Then it poked its nose outside and made enough growth in a summer to earn its place in a pot. The grey foliage is needle thin and grows in graceful, long sprays. The lobster-claw flowers, in shades of burnt toffee, come late in the season but are an extra. Use lotus round the edges of a pot with artemisia 'Powis Castle' as a centrepiece and tawny French marigolds planted in between. The marigolds should not be too squat.
Lotus, because of its graceful habit, is a natural in hanging baskets where you could combine it with a froth of lobelia and dark purple petunias. You could also plant it between trailing geraniums. There is a mixture called 'Summer Showers' - red, pink, lavender, magenta and off-white - all of which produce masses of flowers on trailing stems through the summer. They are of the Balcon type and make big, frothy displays in windowboxes. The individual heads are not as big as zonal or regal pelargoniums, but the habit and the flower-power are better suited to containers.
Ivy-leaved geraniums are equally graceful and have excellent foliage, though they do not flower as freely as the Balcon types. 'Snowdrift' is a clear white with a good habit, 'Alice Crousse' has cyclamen pink heads of flower and 'Amethyst' is deep mauve, good mixed with blue Swan River daisies (Brachycome) and lime-green or white tobacco flowers.
Glechoma or ground ivy is a quiet foliage plant that can give the same cascading effect as lotus. It is not such an elegant plant, but the little leaves, variegated in G. hederacea 'Variegata' disguise harsh plastic containers and provide the bulk that is necessary in pot gardening. Use it with powder-puffs of ageratum and a fuchsia centrepiece. It is also a good backdrop for acid-yellow marigolds.
Because there is plenty of opportunity in our garden for mixing plants in beds and borders, I tend to use pots for things I could not otherwise grow rather than for mixed plantings. The exceptions are the pans and troughs that are, in effect, miniature alpine gardens. I grow alpines in containers because there is nowhere in the garden that fits their Lilliputian scale. They also get better drainage in a container and, in our soggy clay, that is important.
Pots allow you to cheat. There is no way in this garden that we could grow Rhododendron fragrantissimum, for instance, except in a pot where it can sup on special ericaceous compost. And being portable, we can bring it inside, where it is at the moment, scenting the whole house. There are 11 trusses of bloom on it, flaring white trumpets with an occasional red line down the back midrib of the petals. The long stamens are tipped with chocolate-coloured anthers. It is a straggly, weak grower, but the smell is what matters.
Pots are also ideal for lilies which do not thrive in our heavy, soggy ground. They either rot or are devoured by small slugs which cruise about underground. We do not repot the lilies, but they are fed and watered well in the growing season. Last year I tried them on granules of slow- release fertiliser. They seemed to thrive on it. Two 18in pots of 'Citronella' have been sitting undisturbed on either side of the front door for the past seven years. They grow 3-4ft tall, with big heads of relatively small, lemon-yellow flowers. They last the whole of July.
I have never been successful with Regale lilies. Other gardeners keep telling me they are the easiest of all the lily tribe. That makes me feel a complete dumbo, but I find they emerge leaning at an awkward angle and rarely bear more than one flower on a stem. Many come up blind. I would like them very much for their smell. 'Citronella' is not scented.
A series of the same plants in pots, perhaps big hydrangeas, bay trees or clipped box, can also be used to give unity to an area which is not hanging together for some reason. The problem may be architectural, as in an extension which does not blend with the original construction. There may be a fundamental design problem, in that disparate parts of the garden are too divorced from one another. By repeating the same idea, sounding the same note in different areas with matching plants in pots, you can paper over the cracks. You give the illusion, at least, of harmony.
Several companies offer water-retaining gels to mix with compost in containers. Chempak's Supergel absorbs up to 400 times its own weight of water, releasing it to the roots as the compost dries out. When you water, it recharges itself. A 100g pack is sufficient for 10 12in baskets and is available from garden centres for £2.95. You can also order from: Garden Direct, Geddings Road, Hoddesdon, Hertfordshire EN11 0LR (£3.25 includes postage and packing).
Glowcroft estimates that its Swellgel reduces the need to water by up to 75 per cent. Drying out, evaporation and leaching are also greatly reduced. Its 60g pack costs £2.99, the 250g pack £5.99. Basketmate, also made by Glowcroft, is a combination of water-retaining granules and controlled- release fertiliser. A single application feeds a container for five to six months. The fertiliser is not leached out by watering as the water is stored in the granules. A pack of three sachets, each one sufficient for a 12in hanging basket, costs £2.99. A 500g bulk pack costs £5.99.Reuse content