They're not merely fragrant and succulent, but tomatoes are also wonderfully versatile and there's a variety for greenhouses, patios, hanging baskets or even window sills.
Tomatoes originally grew wild in South America and gradually spread north to Mexico, where they were developed as edible fruits. From the 1520s on, the Spanish conquistadors brought the seed of many varieties to Europe, but only a few survived the lower light levels and temperatures. Tomatoes are especially sensitive to the light that triggers photosynthesis in leaves, so the more intense the light, the better the plants will grow. The heat generated by sunlight in their native Peru ranges from 27C in August to 33C in February and March.
Clearly, such temperatures are out of reach in Scotland, and even within Britain heat and sunlight vary enormously. This makes gardening conditions in Scotland very different to the south of England, so you should treat some information in mail-order catalogues with care. The advice is broadly aimed at gardeners in the south and may be inappropriate for you. The Scottish growing season is much shorter, summers cooler and sunlight much weaker. All is not lost, though – while the choice of plants and where to grow them is more limited, you can still expect a tasty tomato harvest.
Tomatoes won't tolerate low temperatures and will be killed by frost, so if you're buying plants over the next two or three weeks, make sure they haven't been damaged by the cold. Choose specimens with green leaves, avoiding plants with purplish and slightly curled ones. Tomatoes need the air to be at least 16C, and the optimum for modern varieties is 20-25C.
Tomatoes can cope with a cold greenhouse but should be covered with fleece if frost is forecast. The plants produce a good root system when the soil temperature is around 15C, so it's safest to plant in a bed where there will be little fluctuation in heat. Soil-warming cables are ideal and a soil thermometer helps monitor the warmth. If you grow your plants in containers, keep them snug by wrapping bubble wrap round the pot.
If you're using a polytunnel or a plastic shelter, delay planting until next month. Although the air in a tunnel reaches upwards of 30C during a sunny day and loses heat slowly in the evening, the lowest overnight temperature is the same as outdoors. Huge fluctuations in heat are bad for any plant, so good ventilation is essential: open the tunnel doors before going to work. Don't put any tomatoes outside until all risk of frost has passed, and delay planting tomatoes outdoors until the last minute unless you're a compulsive gardener.
As with many crops, choose fast-maturing varieties. Tomatoes are divided into three broad groups: bush, or determinate, plants including Tumbler; semi-determinate varieties, such as Losetto, growing to a little over 1m; and cordon, or indeterminate, ones. Two cordons Gardening Which? recommends as best buys are Apero and Rosado.
Bush tomatoes produce lots of fruits often no larger than cherries, and are the speediest growers. You hardly need to do anything to them apart from feeding and watering and you can grow them anywhere. Small table pots or hanging baskets are fine for the likes of Tumbling Tom, one of the tastiest specimens. Bush tomatoes have a much shorter growing season than the others so they're the best and only choice for outdoors. The sun is warm enough in June, July and, to a lesser extent, August, so outdoor tomatoes must grow and ripen quickly. If there are too many cloudy days, like last year, the plants will scarcely grow and the fruit won't ripen. I live at an altitude of 660ft/200m, so wouldn't dream of growing tomatoes in the garden and use a polytunnel instead. Even here, I expect few of my Red Alert tomatoes to ripen in September.
Cordon tomatoes grow well in heated greenhouses, and you will also get a crop in a cold greenhouse. Research for commercial producers has shown the optimum day temperature is 20C with 15.5C at night. Since Scottish gardeners struggle to match that, plants grow much more slowly and you should expect to get four trusses per vine, rather than the seven you'd get in Sussex.
Unfortunately, the larger, more fulsome beefsteak tomatoes are a non-starter in Scotland. They grow superbly beneath the baking Italian sun and put on a decent show in Kent, but the fruit quality and taste will be very poor in a Scottish garden.
If blessed with a decent summer, you can also enjoy the wonderful fragrance of a sun-ripened tomato. The whole vine exudes that unmistakeably sweet smell of ripening fruit and the tomatoes themselves are infinitely more warm and juicy. The summers of 2004-06 seem a lifetime ago, when my greenhouse was permeated with the whiff of mouthwatering tomatoes and even Tumbling Tom, perched on the dyke, proclaimed its sweet fragrance as you passed.