I am an admittedly late convert to floating row cover. I just started using it late last year when I set plants out in the Summer for harvest in the Fall. The floating row cover was to lessen the impact of the sun on tender seedlings and to keep pests, like cabbage whites, off of very susceptible plants. It worked like a charm and the plants under the row cover did so well that I had to wonder why it took me so long. I later noticed that things above ground that I tried to winter over did so much better with several thicknesses of row cover over them than they ever did with just mulch around them. Another victory for row cover.
My opposition was based on two concerns. The first is that I hate to spend on my garden. If I can’t do it on my own, I don’t like to do it. I don’t want to be accused of growing the $65 dollar tomato. The second concern is the environmental cost of another petroleum based product since I don’t think that row cover is made by Monsanto’s silk worms.
But … one can reuse row cover (if you treat it with some care), if you buy it in big rolls from commercial ag sources it is MUCH CHEAPER than buying the small little packages from the home gardening suppliers, it avoids almost all sprayings (with associated ecological and energy benefits) and, it extends your season on both ends and thus lowers the per-unit cost of what you grow. All of these are positives.
So … I bought a roll of lightweight row cover (greatest light transparency but least temperature protection) that is 10′ wide and 100 feet long for about $65 shipping included. It should last me for 5 or six years. Just google “floating row cover” and many suppliers will pop up or visit your local ag supply outlet (farmer stuff, not landscaper/gardener stuff).