This is just bizarre - the matting I've got is not really wicking. In fact, it seems to be somewhat water repellant.
I put some old capillary matting of another brand on one side of a shelf and this new stuff on the other. The old matting was soaked through in minutes of one end being placed in water and has remained drenched ever since. Two days later, the Gardman matting is mostly dry despite me resorting to pouring water all over it to try to get it wicking. Even the bits submerged in water aren't getting fully wet.
I presume from the other good reviews that I've got a bad batch or something, and hopefully as it ages and gets dirty it will start working. But if I hadn't cut it up already, I'd be returning it. A pity, since I was really impressed by the inclusion of a plastic sheet and extra wicking strips.