We had a cold snap early in October and the demand for bubble wrap has escalated on Freecycle. Why? Because bubble wrap is great for insulating plants. Last year I wintered big houseplants outdoors by positioning them against the walls of the house, the pots and the sides of the plants swaddled in bubble wrap.
This year I'm low on bubble wrap because of our house move, so I had to find alternative solutions. We recently bought some appliances and I am using the polisterine packaging to insulate the trunk of a few house plants (I have a few cylindrical bits) and the flat sheets to insulate the bottoms of the pots or to shelter the sides of potted, non hardy plants.
Still, it was not enough so I built a greenhouse out of scrap materials (pictured here open and closed). I used a metal shelving unit somebody had dumped in the street, then wrapped around a broken PVC vacuum bag (usually sold as underbed storage, mine had a broken zip so the top couldn't close anymore) and fixed a torn pram raincover on the front with brown tape and pegs (so it can be opened for watering plants). I left a free shelf on the top of the unit to insert trays of seedlings early next year).
I know you can buy a plastic greenhouse from Argos for little more than £10 but this one costed nothing and used recycled materials that could have ended up in a landfill. I created an extra shelf on the ground by placing a polisterine sheet under the front row of pots. The bulky raincover stretches to accommodate the two rows of pots at the bottom.
There are other ways to be green in the garden. Used coffee grounds can be scattered around tender plants to keep slugs at bay (free from coffee shops); you can make cloches out of plastic bottles; you can use urine (yes, don't be squeamish) and nettles to activate your compost heap (no need to buy chemicals)... If you need more suggestions, just google green gardening, there are so many sites offering free advice!