A 5 gallon bucket would be OK as toms have deep roots The roots need to be kept cool yet the plant needs full sun to do well. Make sure the holes in the bottom are protected from plugging by either a layer of river rock or broken pot shards. Tomatoes need regular feeding to do well. Look at your MG soil to see if it has time release food in it before you fertilize. MG fertilizer, the liquid kind works well for me in the greenhose and around the yard too. Fruit set is best below 90 degrees and you can help by very gently shaking the vines when the flowers are open.
Toms are pretty easy and hope your daughter enjoys the experience and becomes a lifelong gardener.

Ron

Thanks Ron. We ended up drilling holes about 4 inches from the bottom up the sides and putting in some rock and mixing the organic MG and the regular potting soil. It does have a time release fertilizer for 90 days I believe. the patio plant (the dark green one) is a determinate, so I guess that means I dont have to cage it? That one has one flower but its closed. But I think my early girl needs a cage or a stake, with the wind we have been having lately I have seen the plant blowing around. The flowers on that one have opened up near the top, I am wondering if I should strip all the leaves and stems below that flower line? Also I hear alot about mulching on the garden boards do I have to do that?

Determinate means the plant will produce the majority of it's fruit at about the same time and over a shorter time. Indeterminate toms will produce lighter crops but over a much longer time if the conditions are good. Determinate toms were bred for the commercial growers and canners so they didn't have to pick the fields over and over.
Most toms except the "bush " varieties benefit from some staking or cage as they have a lot of stem, foliage and fruit for a soft stem. A stake to tie the plant up will help until you find some wire to make a cage or buy one. The cages are reusable of course so it isn't wasted money.
Mulch serves two purposes, first it helps keep the roots moist longer and second it add a small amount of natural nutrition as it degrades, although not really measurable or sufficient by itself without additional food. You can use strips of newsprint to provide some of the same benefits if you have some available, although not as pleasing to the eye. Stripping leaves only provides stress and a chance for disease to enter the damaged areas so I wouldn't do that.

Ron

Thanks, I picked up a few tomato cages at home depot, they were only 1.69 each..I also bought another 1 gallon early girl variety with some buds and little fruit on it. I picked up some garden mulch on sale for under 2 dollars for a big bag. I guess I am supposed to insulate or protect the roots? I needs to put up something that will shield the buckets so the roots dont cook, but lets the plant on top get some shade. I googled early girl tomatoes on the internet and found that some are determinate and interminate..mixed results,so I have no clue. How do you protect your roots in this heat?

Don't put the containers on concrete in the afternoon sun. If you have some place that gets morning to early afternoon sun that would be good. Also I clump my pots together to limit the amount of sun on the pots. You could put foil around the outside of the pot to reflect some sun/heat too.

Ron

Cover the pot in burlap or something else to protect it from the sun or the roots will get to hot.

My husband picked up some insulation that looks like bubble wrap foil at home depot, its in a roll and I am just going to cover the buckets with them. I have 4 tomatoes on the early girl plants! Green ones! My daughter is so excited and can't wait for them to get ripe. thanks!