Busting common garden myths about tomatoes
Sorry Grandma, this is not true. Tomato plants can't absorb sugar in the soil, they produce it through photosynthesis. The sugar content of a variety is predetermined in the plant's genetics.
Myth: Add chalk or egg shells to the planting hole to prevent black rot on tomatoes. Busted!
Again, a good tip, since they provide calcium to the fruit (since egg shells take a while to decompose, crush or grind the shells to enable them to dissolve faster). The problem is the amount you need to add and the time they take to break down.
Use Seamagic instead, it breaks down faster. But soil composition is usually the problem behind black rot. Black rot occurs because of a “blockage” in root absorption; the best fix is even and frequent watering.
Better: Myth: Planting tomatoes in a trench or up to the first true leaves promotes a sturdier plant. Not Busted!
This is true for seed propagated heirlooms and hybrids. This one is still true for seed propagated heirlooms and hybrids. Planting deeply does help elongate the rooting area since any point on the stem that comes into contact with the soil will root.
This is not true for grafted tomatoes (plants and/or supplies for grafting are available by mail order) because if the scion takes root it will negate the benefits of the grafted rootstock so never plant a grafted tomato too deeply.