Hi Dice,
My assessment is that the landscape fabric is quite inelastic, and does not stretch under weight. My concern is that with the water reservoir constantly filling and dropping via wicking, I was concerned that the potting mix in the basket would be depleted over time.
As the weight of the 3.3 cubic feet of the potting mix holds the inelastic fabric in place, it is not very likely that the area over the wicking basket will "droop" down into the wicking basket.
It only takes a broken air gap if 1/4" or so to prevent the moisture in the water reservoir from wicking up into the 3.3 cu. ft. potting mix. So I erred on the conservative side to make the 1" mound over the wicking basket to compensate for the settling that will naturally occur. Also, by making that cupcake mound initially, the landscape fabric is then in a convex form, and will leave flexing of the material to eventually form a concave shape as the mix in the wicking basket settles. Make sense??
Ray
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