Updated August 5, 2025 at 6:00 p.m.
If your tomatoes are desperately green this summer, it is neither a lack of watering nor a variety problem: the weather is involved.
Forced break
Are you hot? Well, the heat also affects harvests. Usually, during this summer period, tomato plants are full of bright red fruits, ready to be picked. But this summer, many gardeners and vegetable lovers find that their tomatoes remain green longer than expected.
Excessive heat disrupts the production of lycopene, the red pigment that colors several fruits and vegetables.
For a tomato to go from green to red, it must produce a pigment called Lycopene, responsible for its characteristic color. However, this pigment is ideally formed when temperatures oscillate between 21 ° C and 29 ° C. Beyond 30 ° C, Lycopene’s production slowly slows down, or even temporarily stops. The fruits then remain green, sometimes for several additional days.
In addition to blocking coloring, the hot weather can also speed up the breathing of the plant, which diverts its energy towards survival rather than the maturation of fruit.
Too hot summer in Quebec
In July, Quebec experienced several heat thrusts and temperatures far beyond seasonal norms. Some heat waves were scorching, with maximums beyond 30 ° C for at least three consecutive days, particularly in the south of the province.
Good news: this phenomenon is only temporary. When temperatures descend in the ideal beach, tomatoes will resume their natural maturation process and will end up. In the meantime, it is advisable to continue to water regularly, to mulch the soil to keep the humidity and, if possible, to offer a little shade to the plants during the hottest afternoons.
