Adding sugar or molasses to the soil makes tomatoes and other fruit sweeter.
Refuted
Sugar in the soil won't sweeten your tomatoes — roots can't take up sucrose, and fruit sugar is made in the leaves by sunlight. For sweeter fruit: full sun, healthy foliage, a sweet cultivar, and letting it ripen on the plant (a little less water late in the season helps concentrate it).
What is actually known
Roots do not absorb sucrose and carry it to the fruit — the molecule is far too large to enter a root intact, and soil microbes consume it long before a root could. The sugars in a ripe fruit are made in the leaves by photosynthesis and loaded into the fruit; how sweet it gets is set by the cultivar, by sunlight and healthy leaf area, and by ripening fully on the plant, with measured late-season water restriction concentrating flavour in some crops. Sugar or molasses in the soil feeds microbes, not the fruit.
Evidence: not yet confirmed against its 1 source.
what this rests on - one pointer
roots do not take up sucrose; fruit sugars are photosynthate; extension horticulture consensus
When would that grow at your place? →