My tips fortop tomatoes

Temperature changes, overwatering, foliage and feeding can all affect the quality of your toms.Here’s how to grow the tastiest, says Monty Don

My tomatoes are now ready to plant out, in theory. But this is always a contentious decision because they have been happily growing in the unnatural protection of the greenhouse until now, and I have learnt over the years that tomatoes do not take kindly to shocks and variations – particularly of temperature. A nice, steady climate is what they prefer, preferably with lots and lots of sun as the fruit develops and ripens.

That is too much to ask of our British summers, at least in this neck of the woods, so to get the best possible taste I now always grow my tomatoes inside, with the protection of an unheated glasshouse. But I know that most people grow them outside and do very well.

The idea is not just to grow some ripe tomatoes but to get the best taste possible. This is obviously a very subjective thing but certain qualities can be chosen and managed.

Sweetness is determined by the concentration of sugars within the fruit and this is always intensified by heat and sun. Cherry tomatoes are always sweeter than larger ones, so for that delicious sweet hit as you bite into the flesh grow a cultivar such as ‘Sungold’, ‘Gardener’s Delight’ ( larger than most cherries but a superb variety) or ‘Apero’.

Tomatoes also have high acidity and the relationship between this and the sugar adds subtlety to the flavour. Orange or yellow varieties have less acid and therefore taste milder, and a plant with a lot of foliage will convert more sunlight into sugars. Older, heirloom varieties such as ‘Rose de Berne’ tend to have more foliage than modern ones. But in general healthy leaves make for a sweeter taste.

Soil with lots of added organic matter in the form of garden compost, well-rotted manure or bought soil-improver will contain more nutrients and improve flavour. Likewise not watering too much as the fruits start to ripen concentrates taste too. Overwatered tomatoes simply taste watery and in general watering twice a week as the plants develop and then a good soak once a week as the fruits start to ripen is plenty.

Tomatoes hate big temperature fluctuations – and at this time of year that is still very likely as warm days usually mean cool nights well into June. The first indication of this is the leaves curling inwards but the most pertinent effect is that the flavour does not fully develop if the plants get too cold. This is the best reason for growing them under cover but the trick is to keep them as cool as possible during the day by opening the greenhouse wide so that the temperature difference is minimised overnight.

Nevertheless, however or wherever you grow them, there are a few basic things that help them to get established at this time of year. If you are growing in a container do not think that a bigger container will produce more fruit. A grow bag always works well, or use a 7.5ltr pot. However, do use a good peat-free compost and feed weekly with a proprietary high- potassium tomato feed or liquid seaweed.

If growing in soil, choose the sunniest site possible, place the plants in well- manured ground and add a mulch of garden compost. I place my plants about 46cm (18in) apart – no more – and bury them at least as deep as the first leaf. This will anchor them well, encourage roots to grow from the stem and increase their ability to take nutrients from the soil.

Stake or support your tomato plants very securely. You are expecting them to grow into large plants heavily laden with deliciously sweet fruit, so prepare for the weight of this.

But, for all your tender ministrations, the biggest factor in growing really del icious tomatoes is lots and lots of sunshine. And that is something that even the most skilled and experienced grower can do nothing about except pray!

Monty with his ‘Rose de Berne’ tomato plants