Just further confirming the soil rug bug. I had one outside, with a sprinkler on the roof. The sprinkler was on auto and the plants still wilted. I have a picture of my sim watering them. Also, I tried the grow-pro station and this didn't water them either.
I agree with this:
WinMacSims3 wrote:It seems that the sprinkler isn't coded to affect Planter Bowls and Soil Rugs. Here's my testing results.
I had the planter bowl under the sprinkler and had 2 plants was Wilting! but they're weren't being watered. However, I moved them to the ground and they were watered by the sprinkler. I did the same with the plants on the soil rug by moving them on the ground and they were watered by the sprinkler. It does appear that the rain will water plants regardless if the plant is on terrain, planter bowl or soil rug.
Picture of my sim watering plants after the sprinkler has been running:
http://lvlt.thesims3.com/sims3_asset/sim_memroy/null/000/205/653/02/original.jpg