I use inexpensive plastic window boxes as planters for herbs or stuff like starting sweet potato slips. The ones here are old now and getting brittle from sun exposure. Time to get more at the dollar stores. The old ones came from Dollar General many moons ago but they had none today. Family Dollar did. They were $3 each so I got three.

They are 24x7.75" at the top, 6.5" deep.



The sides taper down so the bottom is 20x4". It also has locations on the bottom to drill drainage holes.



The old ones cost a little more but had removable solid bottoms that you could snap on or off. These don't so they'll be solely for outdoor use unless I find trays big enough to sit them on.

If you're interested in getting any of these, you need to get them soon. The dollar stores only buy x amount of gardening stuff for spring and when the supply is gone, it's gone until next year.

I used to use those windowsill boxes around my deck every year, with 4 racks I had built to hold them on the rail of the deck - one 36" one, and three 28" ones. They did great, growing herbs and leaf lettuce every year. I'd put 3 drip emitters on the small ones, and 4 on the large one, for simple watering. Several years ago, when all those started breaking up, as you describe, I switched over to Jr Earthboxes, which also work great. I had to build new racks, but all the same, so it wasn't difficult. I bring them into my back porch, on a cheap shelf, and just a couple of days ago, I started taking them back out again.