we made a couple of these in the spring. I used river sand instead of gravel and after the first one, we didn't use fill pipes since you can just water the soil to fill it up.
the results are great, the plants looked healthy even in full sun during those 95 degree days. plants in the ground were wilted and sad from the heat.
they hold enough water to last a week
the material will be about 200$ for 2 beds, a little pricey but its a one time cost
there's a lot of vids with a lot of different methods, this one is close to what we did
