We bought some eight foot 2 x 4's and my husband used his table saw to cut them into 4' pieces then ripped those pieces into 1/2 inch strips which he then screwed together. (it was cheaper than buying the strips that Mel recommended.). Once he got the grids assembled he screwed them onto the boxes. When we worked the boxes this spring it was very easy to unscrew the grids from the boxes and rescrew them when we are done.

Here is a link that might be useful: LookMaNoWeeds

Milda, check out the FAQ section ... the topic titled "What can I build my grids out of?" has Lots of ideas !! Anyone have any other ideas not already listed there ?

Well, don't laugh, but you use what you have available... and we had bamboo. First we tried putting the grids on top of the boards, but that just did not work well.

So we shortened the canes and dropped the grids inside, and it works great. The canes were cut when green with a 1.5 inch tree trimmer, laid in the pattern, and tied together with garden twine after the inside pattern was selected.

Canes can easily be lifted in fall or next winter and stored, and then reused. Best part - it was easy and free. If the twine rots, I don't care.

I used inexpensive twine which I fed thru small fence staples I pounded inside the beds just a bit above ground level. They really only last a season but it was inexpensive & worked for me.