Last spring, I was sadly disappointed in my new hobby greenhouse’s ability to hold heat. It’s shown above on the day construction was complete, bereft of benches, shelving, pots, and other clutter that later accumulated. It warms up greatly on a sunny day, but on cloudy days and at night the difference between the outdoor temperature and the indoor temperature, even with a small portable electric heater running was only 1 degree! One degree! That’s pitiful! And certainly not efficient enough to protect my precious seedlings. Luckily, 2016 turned warm and stayed warm, so it wasn’t a problem. Having the greenhouse was still a blessing, because it saved young plants from damaging winds and freak hail. It also quickened growth on all the heat-lovers, so it’s worth having, but my plants need protection from COLD, and I really want to start utilizing the greenhouse space earlier in the season. Researching methods to improve the situation was required.
After much on-line reading, horticultural bubble wrap insulation seemed to be an answer, so I ordered the 4 1/2′ wide rolls from ACF Greenhouses ( http://www.LittleGreenhouse.com ). I also ordered the plastic plugs that anchor the wrap to the metal framework. The shipment arrived only two days after I place the order, which was amazing. Excitedly, I carried the boxes to the greenhouse, and paused for a moment, wishing there wasn’t as much stuff already in there. After moving a shelf, a wagon, a stack of pots, and the heater, I had access to the first wall, unrolled the wrap, lined it up, pushed in the first plastic plug and tried to get it in far enough to turn it to lock the wrap in place…and tried….and tried. Finally, I abandoned the wrap, and just tried to put the plug into the empty metal track. It wouldn’t fit! Here’s the metal track the plugs are supposed to go into…
My metal framework is obviously thicker metal (it’s steel, not aluminum like most…we get 60 mph winds and heavy snow loads some years so I opted for strength) than the plugs were made for. An attempt to fix the problem followed. Focus on the far left plug. See how small the opening between the part that turns in the framework and the base is? The top plug is one I filed slightly to make a larger opening. Notice I did not weaken or reduce the post that holds the turn-in part. Filing a couple of the plastic plugs was not easy (I worked while I watched basketball so it was not a total waste of time!) but it was do-able. However, I wasn’t looking forward to filing 100! I bundled back up and went out to try again. The plug would fit into the slot with the insulation, but when I turned it to lock it, the base snapped off the plug. Obviously, this wasn’t a solution. I tried everything I could think of including clothespins, bent wire paper clips, flat-headed bolts, wiggle wire, etc. It must be something that is easy to install yet just as easy to remove. After all, the insulation will only be in place until mid-May and then it comes down. Plastic melts inside my greenhouse even with two roof vents and an automated fan vent. Believe me, I learned that one last summer and won’t leave anything plastic in there again. Finally, I remembered some metal clips in my husband’s desk and I “borrowed” them. They come in assorted sizes. The small 1/2″ ones fit in the track, but didn’t have enough strength and popped off. Happily, the larger ones (1-1/4 “) also fit and for the most part work well! (Happy dance here!) They aren’t cheap ($4.79 for 15 at Staples and it took 9 pkg.) but I figure they will last the rest of my lifetime easily, and they are easy to use. It still wasn’t easy though. Climbing a ladder and holding the wrap over my head while trying to clip the clips wasn’t fun. Neither was working the insulation around and behind my benching (which is WAY to heavy for me to move again… putting it in was hard enough and I’m a year older!) but by crawling underneath and carefully pulling, climbing on top and carefully feeding it downward, I was finally able to get the wrap installed. It would have been a lot easier if the greenhouse were empty, so I wouldn’t have to move everything a dozen times, but that will never be the case now or in the future, so it’s a just-do-it situation. Once the wrap was all clipped up, I used inexpensive clear packing tape on the seams (overlapping the wrap a bit) to secure it and also around the vents. (Another happy dance would have been appropriate, but I was too stiff by then to move!) I did reset the thermometer, so I could compare the outdoor and indoor low temps. The next morning, I hurried to the greenhouse, eager to see how much difference the bubble insulation wrap had made. Unfortunately, the sheets were hanging loose wherever there were seams. See it sagging open just left above the potting bench? The packing tape had not held. How can that be when anything that arrives wrapped in bubble wrap and fastened with tape is nearly impossible to open without a sharp blade? Somewhat deflated, I ordered a roll of 4″greenhouse tape $15 (as suggested by ACF, but I was trying to save a few pennies, which were now spent on additional shipping costs of $16) and re-taped all the seams. I also ran a bead of silicone sealant on the outside, wherever there were little gaps between the greenhouse framework and the wood foundation, because when I was crawling around on the floor, I noticed cold air coming in here and there. It was finally finished!
After 3 nights of temperatures in the teens, there is a 6 degree difference. Still not great, but better than 1 degree WITH the heater. Tonight it will be mid-twenties, so I’ll monitor the temperature with the heater running. I’m hoping to see enough difference in heat retention to make it worth A: the expense…$36.95 per 4.5 x 25′ roll, $55 shipping….it took 4 rolls for my 10 x 12′ house, plus the clips and tape, and B: the effort installing the wrap. I’m already not looking forward to putting it back up for next season, but if it really, really helps I can grin and bear it. Crossing my fingers that this works, because there are over 1,200 plants that need to come out of the basement… over twice that many more seedlings still to be transplanted, and winter seems to be hanging on stubbornly with bony fingers.