If you search for it; There is a sticky tape zipper that is designed for exactly this situation. It is about 6' long. You stick it on your plastic where you want to enter, and then unzip the zipper, and cut a slit the length of the zipper. Walk in. When you come out of grow area, you merely zip the zipper up, and grow area is safe and secure.

You can also frame a 4 foot door area and buy/insert some folding louver doors to hide the plastic wall/door.