Red red vine: It's time to order your tomato plants but choosing which varieties to grow can be the trickiest part of all

'Costoluto Fiorentino' or 'Brandywine'? 'Gardeners' Delight' or 'Sungold'? For weeks, tomato names have once again been rolling round my head like mantras. Until this year, my only option has been to grow tomatoes outside and I've become disenchanted. The plants regularly got blighted before the first fruits had even set. Now I have a greenhouse, with a long earth border along the west-facing wall. Perfect for tomatoes, I thought, especially if I bought them in as plantlets, which would mean I could grow plenty of different kinds.

Then a letter arrived from Pippa Lane of Westbury, Wiltshire, who has a 20-year-old Robinson greenhouse which travelled with her from her previous garden in Northumberland. "Imagine tomato plants growing really well," she wrote, "ripening tomatoes, warm weather, all very encouraging. Then strong winds from the southwest (as you have too) and lots of rain, but still very warm.

"The automatic vents are open, and the wind blows the rain horizontally under the vents, all over several tomato plants. A week later the first awful signs of blight, drastic measures taken, but even so, within three weeks all the leaves picked off, the worst plants removed and a potential tomato glut reduced to a very meagre harvest."

Oh Lord! My blightless dream didn't last long. "If you come across any practical way of preventing this, it would be very good to hear of it," continues Mrs Lane. "It would save one from having to rush out and disconnect the vents every time the rain arrives horizontally this summer." I've no bright ideas yet to offer Pippa Lane. My hopes are pinned on a sunny, bright and rain-free summer. Some hope!

Anyway, in optimistic vein, I'm pressing ahead with plans to order six plantlets to go in the greenhouse border – they need to be planted 50cm (20in) apart – and perhaps a few more bush tomatoes to grow in pots. The big lead trough that has been holding pots of hippeastrums, freesias, ornithogalums, hyacinths and the like during winter and spring, will be empty during summer. If I filled our biggest plastic pots (37-40cm across) with compost, they could stand in the trough while the potted bulbs are outside. Bush tomatoes should be quite comfortable grown like this, looking out of the south side of the greenhouse, but they'll need regular watering and feeding.

Orders for tomato plants need to be in by the end of this month and, given the amazing variety of tomato plants on offer, it's not easy to decide on a shortlist. Bush tomatoes tend to fruit earlier than cordon types, and they often bear their fruit all in a rush, over a period of about four weeks. Cordon tomatoes need to be tied in to a support as they grow, but because they keep producing new trusses of fruit as they grow, they crop over a longer period..........

Bush tomatoes don't need training or pinching out. You just plant them and let them grow as they will. Cordon types produce sprouts of new growth from the angle of each leaf and these need to be pinched out as soon as you see them. For the narrow greenhouse border, I need cordons, to be tied in to canes as they grow. 'Sungold' is on the list, because all who have tried it tell me it is the sweetest, best-tasting tomato they've ever grown. It bears small yellow fruit and is early, often ready to pick in late June.

The cordon tomato 'Gardeners' Delight' bears the same kind of cherry-sized fruit, in long trusses, but they come slightly later than 'Sungold'. For the rest, I need varieties that bear slightly larger fruit, perhaps 'Alicante' as the reliable old banker and 'Costoluto Fiorentino' for an authentic taste of Italy. This last one has red ribbed fruit, full of character. For tomato salads, you need solid, beefy fruit that slice almost like bread. 'Super Marmande' is perhaps the best choice here, though the beefsteak tomatoes need heat, and are rather slower to crop than other kinds. I won't be picking them before August.

But what should the last cordon tomato be? 'San Marzano' bears red plum tomatoes that are said to make the best tomato sauce of all. But I'm also tempted by 'Brandywine', an old Amish variety that bears huge, pink fruit. It's not reliable though, sulking some years and flourishing in others. You also need to help it pollinate successfully, whisking a paintbrush among the flowers, or watering from above to help the fruit set. Should I play safe and try 'Pannovy' described in Simpson's catalogue as bearing "smooth, deep-red fruit with good disease resistance and excellent flavour. Productive and consistent." No. It's too boring to play safe. I'll go with 'San Marzano', although I know from previous experience that plum tomatoes aren't always easy in our climate. Even in a greenhouse.

Simpson's offer a larger range of tomato plants than anyone else I know – 68 different kinds. Plants are delivered between mid-April and mid-May. Our greenhouse border was excavated (through concrete) down to about two feet and then two-thirds filled with our own compost. We topped off with bought compost and since nothing has yet grown in that border, the tomato plants should have a good start.

The plantlets are best set quite deep, so the first pair of leaves sits almost on the ground. New roots will often grow from the underground stem and the more roots the better. Tomato plants are greedy. Stick in bamboo canes for support at the time you plant. Most cordons will grow to at least 200cm, though 'Sungold' may get taller, 'Super Marmande' not so tall.

In August, stop the plants by pinching out their tops. Then they can concentrate on ripening the fruit that has already set. And I, having sorted out the tomato order, must now think about a way of solving Mrs Lane's difficulty. All suggestions gratefully received.

Simpson's Seeds Ltd, The Walled Garden Nursery, Horningsham, Warminster, Wilts BA12 7NQ, 01985 845004, e-mail: sales@simpsonsseeds.co.uk, website: simpsonsseeds.co.uk. Orders for tomato plants must be in by 28 March. Six plants of the same variety cost £7.50, six mixed £9