Garden Myths Vegetables

Garden Myth: Adding Sugar to Soil Makes Tomatoes Sweeter

By Larry Hodgson

Question: I read on Facebook that if you put a cup of sugar into the hole when you are planting tomatoes, then the tomatoes will be sweeter. I did it last year, but I wasn’t sure if it really worked. Is this something I should keep doing?

Laetitia Martin

Answer: No. It simply doesn’t work. And that applies to adding crystalline sugar to a planting hole, sprinkling it over the soil at the plant’s base and watering the plant with sugar water, other false information shared online.

Tomato roots (and indeed plant roots in general, other than those of a few saprophytic [parasitic] plants) aren’t able to absorb complex molecules like sugars, so the sugar can’t simply flow into the roots then be taken up by the sap into the plant and carried as far as the fruit, thus making it sweeter. Instead, microbes in the soil would have to break the sugars down, largely turning them into carbon dioxide and water.

Instead, plants produce their own sugar from carbon dioxide and water inside their leaves, manufacturing it through photosynthesis as a way of storing energy.

Of course, adding sugar to the soil can stimulate microbial growth which could eventually be beneficial to the plant. Unfortunately, that doesn’t always result in the right kind of microbes. Adding sugar to soil sometimes stimulates fungi and bacteria that are harmful to plants. So, adding sugar as a sort of weak “fertilizer-once-it-breaks-down” product can’t even be recommended.

Sungold tomatoes on the vine
The tomato ‘Sungold’ is often judged the sweetest tomato in taste tests. Photo: AirUbon, depositphotos

Not that growing conditions have no effect whatosever, but the sugar content of any tomato variety is still largely predetermined by its genetics. Therefore, the best way to have tomatoes with a sweet taste is to plant a variety known for its sugary flavor. You’ll discover that smaller tomatoes, such as cherry tomatoes and grape tomatoes, tend to be the sweetest. That can include such varieties as ‘Sungold’, ‘Rosado’, ‘Apero’, ‘Sugar Snack’, ‘Floridity’ and ‘Sakura’. Then give the plant the best possible growing conditions: full sun, rich, well-drained soil, attentive watering, reasonable but not excessive fertilizing, etc. That will give you deliciously sweet tomatoes.

And you can always sprinkle sugar onto slices of less-than-sugary tomatoes to improve their flavor to your taste.

Save your sugar for cooking. Added to the soil, it really contributes little of any value to plants.

Top illustration: Halloweenn & Pogorelovaolga37, depositphotos &, montage

5 comments on “Garden Myth: Adding Sugar to Soil Makes Tomatoes Sweeter

  1. I actually saw this described on a television gardening show a long time ago. Each plant got a pound of sugar!

  2. Amy Diane Roberts

    I have heard of putting salt around the tomato plants but not sugar. When I need help with my plants i always go to my mom and dad.

  3. Amy Roberts

    I have heard of putting salt in the soil to give tomatoes a more robust flavor. Haven’t ever tried it considering my mom and dad are my gardening go two’s.

  4. ooh….I just found out about this

  5. sugar in soil,WOW.
    That a new one on me.I would never believe anything on FB.

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