Gymgirl wrote: Indeterminates will grow in the Earthboxes, they will get as huge as they're supposed to, and they will need staking of some kind...Here's a staking system I'm using for the first time this season. You could install a frame directly over your Earthboxes and run lines down to each plant.
It is the neatest, most carefree system I've found, and no bulky cages or stakes, either.
I used old 7' galvanized fence posts I have and pounded them into the ground 24". Then, I used couplers to extend the height back up to 7', by affixing 18" of PVC pipe. The overhead is joined on the ends with elbow couplers and is a 5' section of PVC pipe, as well. I could swing from that frame!
In the off season, I'll drop a net and use it for the snow and sugar snap peas!
Here are a few pics to show the frame, and the tomato progress. I have a line of 3 indeterminates planted. Each plant was supposed to be pruned to have only ONE main stem, but, I decided to go with two main stems, letting it branch into a 'VEE'. So, on an internal bed width of exactly 4', I have 8 plants in that row. Next time, I'll only do one main stem, although, the lines are holding quite nicely, and they are starting to crank out tomatoes.
I've got two Sioux and one Virginia Sweet in the line.
You could do this quite easily if you set your EBs end to end. You'd have excellent spacing between the plants. Depending on how many boxes, you might need to install a middle pole to brace it, and use a "tee" coupler in the middle.