2010 was an expecially hard winter here in Alabama. We had one period where it never got above freezing for about a week which is very unusual here in the south. Because of this we lost a lot of plants. I’ve been growing bamboo commercially for about 15 years and that was the first time I’ve lost any significant number of plants due to the cold. Some plants that did survive had all the new root buds killed so they did not send up any new shoots come spring. The loss of so many plants represented a lot of work and I decided I had to do something to prevent it happening again, so I decided to build a large greehouse. Actually it would be a “cold frame” as I did not plan to heat it. I just wanted to keep it a little warmer than outside temperatures and protect plants from the drying winds. I hoped to place several hundred bamboo plants in the cold frame. I had leveled a new plant holding area this summer that utilized a retaining wall made of treated timbers. This became the back wall of the cold frame, 2 feet tall. This meant I used two foot sections of pipe at the end of the hoops to raise them to the same heigth as the first hoop on the wall. This gave me an interior height of 10 feet so it’s nice for bamboo. This is a collection of pictures from the construction. I have filled the greenhouse with bamboo (before I finished) and we’ve already had a period of temperatures in the low 20′s or teens. I noticed some of the Black bamboo at the top of our hill had suffered some cold damage.
The new planting area has been leveled with fill dirt and a retaining wall. New groundcover fabric has been installed. I used 4×4 pressure treated timbers buried 24″ in the ground (with concrete) and placed 2×6 boards behind them. I wanted a low cost wall that would hold up for at least 5 years and this should do it. I placed tar paper behind the wall and back filled.
Here the first hoop has been installed and anchored to the retaining wall. I drove 1″ steel pipe into the ground about 18″ and set the ends of the hoops down over them (the hoops are 1 and 1/4 inch size and just fit). I then used self tapping screws through both pipes. This should keep the frame firmly on the ground in high winds. I also used pipe clamps to attach the pipes to the retaining wall as well as the 1×4 lumber base around the perimeter of the cold frame.
The first few hoops have been installed and tied together with horizontal steel pipe stringers. Once I had the first two up it was much easier as they supported the new hoops as I slid them onto the horizontal stringers. Once a had a few up I made sure they were correctly spaced and used pipe clamps to tie the hoop to the stringer. With the anchor pipes and the horizontal stringer the frame was surprisingly stable.
This end will contain the door. It is framed up with decay treated lumber. I cut the rounded pieces that frame the arch with a bandsaw. This was a tedious process but looks pretty good now that it’s finished.
The polyethylene plastic is placed over the hoops. I rolled it out along the top where there is a horizontal pipe going the full length of the greehouse. I then let it drape down on both sides. I tacked the plastic down with roofing tacks just to get it in place. Here I’ve trimmed off the excess along the side. This turned out to be much easier than I thought. The plastic stayed in place nicely and was easy to stretch fairly tight.
I moved the bamboo into the greenhouse as soon as I had the hoops up. I needed to move all the bamboo plants from my former holding area so I could begin working on that area. I’ve got about 500 bamboo plants stored now. I’ll put in about another 100, mostly Golden and Black, and if we have another really bad cold spell I can probably squeeze in another 200 or so. Bamboo in the greenhouse are the more popular species but not the most cold hardy. I finished the bamboo cold frame in December. In early January we had another very cold freeze. We started with a few inches of snow and ice. I went out several times during the night to knock snow off the greenhouse to keep it from building up too much weight. This is a very unusual experience in Alabama. Over the next 3 nights the temperatures dropped into the teens and never got above freezing during the day. I was so glad to have my more valuable bamboo in a protected cold frame!
Completely closed in! The bamboo is inside, let the cold come on. I’ve moved in some Arrow bamboo, along with a lot of Giant Gray Henon I potted up.
