I'd have to do some research on that one! I know if they get too much nitrogen they only grow leaves and not fruit. Also if they are overfertilzed it weakens them and attracts insects. Do you have a county Ag. agent can ask?

what does the box say?

to fertilize every 2 weeks....

Well it won't hurt them, but personally I would hold off.I tend to think miracle grow boxes overstate the necessary frequency of feeding. I started out feeding more frequently and have reduced to my the current level of feeding once at the beginning of the season and again half way through. I do apply compost and I'm sure it has some nutrient value but its probably not much. Although as Dr. Carolyn manages with just a bit of compost, I suspect spectacular results are possible with even less fertilizer than I use.

Are the plants in the ground or in a containers?

Plants that are grown in any kind of container will need feeding more often than plants that are grown in the ground because each time they are watered, the water run off carries away vital nutrients. Many container gardeners feed with a dilute fertilizer every week or two.

If your plants are in the ground, you can feed them a balanced fertilizer such as 10-10-10 or 8-8-8 or a tomato specific fertilizer after you have a fruitset (it's often suggested to do that when the fruits are about an inch in diameter, of course if they are cherry tomatoes, it will be when they are smaller.) You can feed again about every 4-6 weeks. Work the food into the topsoil but keep it at least 8" away from the stems and be careful not to dig too close to the roots or you can burn the plant with the fertilizer.

Betsy

My 2 cents worth. Feed the soil, not the plant.

OK, feed em both :-) (use MG & compost)

I use MG, but I don't use it every two weeks. If I did, I'd most likely go with a weak solution (mainly because I'm frugal).

Ever considered making compost tea? It's supposed to really help feed the soil.