One of the pitfalls to a plastic greenhouse is the way in which they are ventilated. Typically, greenhouses are ventilated on the roof.

The Cheese Making Process
The cheese making process will give you different results in terms of different kinds of cheese every time you let it go through a variety of conditions.

However, with plastic greenhouses the ventilation comes from hinged sashes on the walls of the greenhouse. I'd highly suggest you put sliding panels for ventilation in the gable ends of the greenhouse; this will allow for maximum air flow and ventilation.

Corrugated plastic, slightly rust-tinted in appearance when new, darkens as it ages, gradually shutting out some of the light.

Building the Transparent Plastic Greenhouse

You can use plastic on any type of greenhouse structure- lean-to, span, partial span, or free-standing.

If you plan on eventually adding greenhouse glass, you will want to ensure you plan for the greenhouse frame so it can hold glass; when you're ready to install it. However, if you never have any intention of adding greenhouse glass, you can help to reduce the construction costs of your greenhouse, by using lower priced, smaller pieces of wood for the frame.

The sheet plastic comes in 100-foot rolls in widths of 10½ to 20 feet. It takes two people to put it on. One tacks the plastic at one gable next to the top of the greenhouse. The other holds the roll of plastic, releasing enough to cover three or four sash bars while pulling tightly on the roll. The first person then tacks on lath down to within 8 inches of the bottom of the strip of plastic.

The second length is placed under this 8-inch lap, so there is a lap of about 6 inches, and the second length is then tacked in the same way. If the lap is about 6 inches and the plastic is pulled tight, there is no need to seal the laps since they will stay together even in strong winds. If you want a double-layer covering-and it's advisable-the inside layer can be attached with paper disks and tacks. Be sure to allow an inch or so between the layers for "dead air" insulation.

In my greenhouse, ventilation is obtained through doors and louvers in each end. Other greenhouses are ventilated by doors and side drop vents.