Tomato Growth Requirements
Tomatoes are warm-season crops and sensitive to frost at any stage of growth. If subject to temperatures below 10˚C, crops suffer from delayed seed germination and slow early growth. The cold will also reduce fruit set and delay maturity. Similarly, temperature extremes of over 35˚C will reduce fruit set and restrict red coloration. If water stress and high temperatures occur together the plant will produce soft fruit.
The optimum temperature range for tomatoes is between 18 and 27˚C. Above 27˚C, flower formation is adversely affected. However, with the introduction of modern varieties, tomatoes are increasingly grown in higher temperatures, tropical conditions. Maturity dates range from 60 to 90 days.
Tomatoes are sensitive to low light conditions, requiring a minimum of 6 hours of direct sunlight to flower. However, if the intensity of solar radiation is too high, cracking, sunscald, and uneven coloration at maturity can result. For this reason, under greenhouse conditions, the shading of fruit is essential. Day length is not critical to the production of tomatoes and so greenhouses occur across a very wide range of latitudes.