In the case of backyard tomatoes, it's a good idea to significantly reduce watering as the fruit begins to turn red. This way, the size is already reached and flavor is in full production.
Deficit irrigation also helps conserve precious water resources.
No, deficit irrigation doesn't refer to tossing the national budget into the ocean. Instead, it is a method used by growers to increase the amount of sugar in foods such as tomatoes, basil, pomegranates, and peaches.
Plants have flavor because they contain sugar and volatile chemicals. Aroma plays a major role, as well, but we will leave that for another day. The volatile chemicals that generate flavor are used by plants as defense mechanisms. The pungent taste of many herbs is a perfect example of strong flavors being used to discourage herbivore and insect feeding. As water levels within a plant are reduced, those flavors get stronger. This is where deficit irrigation comes in.
The opposite of dilution
When the water supply is significantly reduced, sugar and flavor molecules become concentrated. More water means less sugar and flavor per plant, while less water means more flavor. It's a simple matter of dilution.
Some crops are bad choices for deficit irrigation. Cucumbers, melons, and other members of the squash family are more likely to turn bitter than better without adequate irrigation. For crops well suited to this practice, there is still a downside. Improperly done, deficit irrigation increases the risk of stunted growth and smaller fruit. Start too early and you end up with fruits and vegetables that are weaker, drier, and not what you were hoping for.
You can grow a surprising amount of food in your own yard. Ask me how!