It depends in part on which type (determinate or indeterminate), variety (some are much bigger than others), how you plant to support them and how much, if any, pruning you plan to do.

Can you give us more details on those issues?

Dave

I would like indeterminate as I want them through out the year. I plan to cage them and do heavy pruning. I have yet to pick a variety honestly I was looking at the Bonnie 5-in Tomato Plant since this will be my first year.

What i was thinking of doing is a box line one foot from the sides and 2 feet apart.

How close can I plant carrots and lettuce to the Tomatoes? How close to the side of the box can I plant.

Thank you for the help.

Lettuce and carrots, lettuce especially can be planted within 4-6 in of the edge although it may overlap the edges as it grows. Carrots will work with that same edge spacing but not flush. Solid walls, when the roots of the plant hit them, cause coiling and twisting of the roots so needs to be avoided when possible. Tomato plants at least 8" out from the wall work best IME.

Indeterminate varieties, if grown in actual cages rather than those three ring junk things, and if carefully pruned would probably do ok with 4 in a 4x4' space but it will be very crowded, difficult to access for harvest and to monitor for pests. Plus you don't indicate where you live so I can't really address the disease/air circulation issues you might have.

Staked and heavily pruned they would do fine in that sapce but the pruning costs you production.

Personally I would do 3 tomato plants in that space. You could plant some extra lettuce around it but the plants will shade the lettuce. That can be good or bad depending on your weather.

Given the small size of the bed you might want to do some reading over on the SQ. Foot Gardening forum here. It is a very different method than usual but lets you maximize your growing space when it is limited.

And also keep in mind that lettuce has a limited season so it can easily be followed by planting another tomato plant in its space once the lettuce is finished.

Dave

Digdirt thank you for the great information. I live in south Missouri right now. (We are a Military family and move often.) I plan to build one box this year and when we move next year build a few more.

For the sunlight it should get 8 to 10 hours a day of direct sun light.

My plan for the lettuce will be to plan a row and when it gets close to the end plant a new row next to it. I want to try and go back and forth between the two areas in hopes of extending the time we have lettuce.

I'm also thinking of having a very small green bean area just to experiment with them for next year.

I agree with you about 4 and I think I will go with 3 in a triangle set up. We don't eat a ton of tomatoes and I just want to make sure we have a handful each week. They sounds great on a burger or BLT.

I will defiantly check out SQ section. Sadly since we only have a year left here. I don't want to spend to much on starting the garden up this year just to move.

Number One: Lettuce is a spring crop and will be gone by early june (or even sooner). So, you can plant as much lettuce you want in the whole area. Then when it comes to tomato plant out time, just clear a one square foot area and plant a tomato in there. As tomatoes grow, just keep harvesting the lettuce, closest to the tomatoes until they are all gone. So this way, instead of a 4 x 4 area, you can dedicate a 4 x 6 area for tomato-lettuce . in a 4 x 6 area you can plant 6 tomatoes (that is 4 sqr-ft per plant. That is plenty). You can either stake or cage OR a combination. For example, cage every other one and stake the ones between cages. Or run twine from cage to cage to support the one between them. Pruning is an option to keep thing under control and manageable. I would restrict to the main and two branch out per plant.

Indeterminate tomato plants can get quite big. Mine were
around 12' tall last year. Six fit up the cage and six feed
back down the cage.

I train my plants to 4 main leaders and put one on each
upright. I still get more production than we can eat and
end up giving away lots of tomatoes. I don't worry about
the loss of production....what would I do with more????

Check out my PVC tomato cages for a possible support
system.

Be sure to buy bush green beans and not pole beans.
Pole beans also grow 8-10 feet tall.

Also, by planting your lettuce in the shade of the tomatoes,
you could extend you lettuce season.

Here is a link that might be useful: Tomato cage plans

I would suggest taking the sod out from under the bed first. Then till the heck out of it. Depending on your area, and clay content I would advise to add in a lot of builder's sand, and till it in as well. then add the amendments,and final step the bed itself. I did this myself this year. Last year I had uneven draining, and it wreaked havoc on my tomato plants when the roots hit the clay. They will root deeper than many think they will.

If the tilling, and sand are not an option I would do a few inches of pea gravel on the bottom, then the bed itself with the amended garden soil. Since the soil will be heavily amended you can space the tomatoes a little bit closer than the labeled spacing. Though I would advise not going closer than 6 inches closer than plant label spacing.