Greenhouse potting bench
My greenhouse has what I thought were potting benches. But mine are more like troughs lined with heavy duty black polythene. I discovered that the pea gravel surface is topping soill. Is that right or should it just be solid pea gravel? The soil is rich fodder for weeds which sprout up everywhere. One trough is about 6' long, 30" wide, and 9" deep. One of these runs the length of the greenhouse, the other cross butts it so it is about 2' long but width and depth the same. I am quite happy to get all the soil and pea gravel out but what should I then fill the troughs with? As you can tell I am a novice greenhouse gardener and would be so grateful for help.