FWIW, my 2¢:

Quick google shows lots of fotos, and I suppose if you are going to cover your boat/RV/ATV anyway and move it out to start some seeds, it might be an OK way to go if there is no other alternative.

But in my view if you want a greenhouse or high tunnel, purchase a greenhouse or high tunnel product.

Dan

The research I've done on these is that light transmission is 70-73% which would be adequate for holding plants till planting time.

I agree with you about a greenhouse/high tunnel. We have two already but we wanted a "holding" greenhouse for additonal plants that we sell. This would be used for approximately 1 month, then moved out of the way. The number of "portable greenhouses" is amazing but most of them are flimsy made with 3/4" cheap powder-coat frame, PVC, or those knock down types that are not very large. The Rhino/Shelter Logic use 1-5/8" galvanized steel with bolts & screws rather than just inserting the frame together. Still trying to come up with an alternative to something we can quickly put up/take down or at least move out of the way and still do the job.

Sorry a little late with this, but we have a "Weatherguard greenhouse" (a small hoophouse) for overwintering plants and it is extraordinarily well-made, and the translucent, reinforced cover shows no signs of wear after 3 winters now.

Dunno if they make one in the size you need but worth a look.

Just had a look at it - not a bad price for a 20x12' building. If it lets 70% of the light thru, that would be enough for seedlings, especially if one is willing to rotate the plants from the north wall to the south one weekly. That thing would hold ~1300 3" nursery cells in standard flats.

Mike