Young tomatoes vulnerable to heat
Newly transplanted plants’ leaves sometimes look bleached, but most outgrow the condition
QLast year, not long after transplanting my tomatoes, some of the leaves took on a bleached look. What would have caused this and how can I prevent it this year?
A: In years when there is a fast shift from cool, wet conditions almost straight into summer heat and bright sunshine, young plants like newly transplanted tomatoes will suffer from the condition you describe, called sunscald. Soft, new leaves are vulnerable to damage from hot sunshine.
As the plants develop, they almost always outgrow the condition and survive to become healthy and productive. Often, a spurt of high heat and intense sunlight is followed by a slight cooling of temperatures, giving affected plants a chance to recuperate.
QI was recently speaking with a gardener who told me that he has a long-standing habit of picking his tomatoes when they are fully sized but still green. He ripens them indoors. Does this make any sense to you?
A: It makes sense at the end of the growing season, when it cools down enough to make vine ripening unlikely. Then, sized up tomatoes can be ripened indoors. And commercially grown tomatoes are sometimes picked green, before they ripen and soften, for shipment to stores.
In home gardens, at the height of the tomato season, in my opinion it is folly to pick the fruit still green.
It seems to me that the whole point of growing tomatoes at home is to enjoy freshly picked, vine-ripened tomatoes at the peak of full flavour and nutrition.
The riper a tomato, the more nutritious it is. And for the fullest possible flavour, pick tomatoes in the late afternoon on a sunny day, when the sugar and flavour chemicals are most concentrated.
For peak quality, harvest tomatoes within five days of the fruit becoming evenly red (or yellow, orange, dark purple or pink according the variety).