I braced each one with two pieces of 5' rebar sunk halfway in the ground. I only sunk the TTC bottom tines 6" since the rebar is doing the work. We get major wind gusts. No way I would use them without a brace.

I wonder what diameter of rebar is best?

I use 1/2"

I would stabilize them with rebar but it need not to be 5" tall. Take 2 or 3 piece of 3ft long rebar , drive them down about 18" deep and tie the cage to them.

Remember that you are trying to keep the balance, as the weight on the cage is acting mostly downward in the direction of gravitational pull.

If you don't have rebar , any 2 by 2 lumber will do.

Sey

18" buried would blow over here, but you may not have our wind.

For working with rebar or any longish post, this is indispensable:

http://www.homedepot.com/p/Everbilt-Fence-Post-Driver-901147EB/204331909

Yea, I really have mild weather compared to some of you. Still, I see a couple cages leaning. I suppose my t posts are more than ample. I can see where the 1/2 or 3/4 rebar would be a cleaner look. Of course, the plants hide the posts once they get big. Thanks for the ideas. Ed of Somis