I just built an 18x48 high tunnel with the plan to grow a crop of container tomatoes this spring. I need to choose a material to cover the ground inside. The piece of ground has Johnson grass very badly.

I was just going to buy typical weed cloth, but I am now noticing that the cheap stuff is not UV-protected, because it is meant to be buried. The UV-protected flooring fabric is really expensive. Hummert has a $300 minimum order; Farm-tek's flooring product would amount to $400 just to cover the ground. That's more than the cost of the plastic to cover the structure.

I have a few rolls of the thin black plastic used as mulch. My plants will be in 5-gallon buckets, hopefully on pallets. The plastic will work to keep weeds down, but I'm not sure if holding water will be an issue. I could buy one big tarp for the floor for $65, but I think it would hold water, too. The runoff from watering plants is perfect for growing algae, and I could do without pools of green slime everywhere.

Paper is another option, at least for under the pallets. I only need the mulch to work for a few months. It would be nice if it would last through the summer to try and kill some of the grass inside the high tunnel. I'm going to till the ground inside in late summer and plant a fall/winter garden directly in the soil. If the cheap, non-UV protected weed fabric will last through one summer, I can just use that.