I'm determined this year to really throw myself into the garden and want to get off to a flying start. So I've been on the lookout for a new propagation house. I do have a cold frame which I will also put to good use, but it's really not enough as I also want to house a number of plants in pots during winter. Although there are plenty of propagation houses on the market I've had a plan for a while to build one using clear tarpaulins over a bamboo framing. This may sound a little temporary, but I'm confident I can get a good five years out of it if I spend a bit of time getting things right.
Firstly the floor needs to be solid and I've taken the opportunity to get rid of some old broken concrete. I've also used sleepers, which I ripped in half using a skill saw, as boxing to hold the fill together. The bamboo was collected locally and was free. I was impressed in Asia with the use of bamboo as scaffolding: it can go up tens of floors and is held together using cable ties. I figured a bamboo frame in my backyard would be sturdy enough to go the distance. I built two of the walls on my patio using a hole cutter to create slots for the bamboo, then drilled holes for the cable ties which hold the bamboo in place. I was going to build a light timber framed door and cover it with tarp off cuts and I still might at a later date. My wife joked that if you didn't use this for a propagation house you could use it as an emergency shelter. Perhaps you can keep a copy of this article in your civil defence kit - just to be on the safe side.
Prepare a flat area to place your propagation house on. I placed half an old tarp on the ground which will stop weeds growing through the floor.
Build timber the edges to the dimensions of the propagation house. I used macrocarpa sleepers cut in half which are 100x100mm then nailed them together and pegged them to the ground using H4 tanalised stakes.
Drill holes through the timbers and thread wire through. The wire will hold the bamboo framing in place.
Fill the timbers with hard fill. I used broken concrete and then topped it up with fine gravel to make it level.
Measure and cut the bamboo framing to the correct lengths and heights then measure and cut the holes for joining the bamboo together. Because the bamboo is all different lengths, the holes will be different sizes each time.
Slot the poles together then drill a set of holes through each piece and join them together using cable ties. Brace each wall diagonally both ways.
Erect two of the walls, attaching them to the floors using the wire ties. Work your way around the framing, bracing where necessary. I ended up bracing all the walls and the roof diagonally both ways as well as installing a set of rafters to stretch the roof tarp over. I also included two posts for the door.
Once the framing is complete attach the tarps, starting with the walls first. I tied the tarp to the framing using cable ties. Attach the roof tarp making sure it wraps right over the wall tarps to make the propagation house weathertight.
To make a door, measure the gap between the posts, top and bottom and make a rectangle to fit. Brace the rectangle diagonally and horizontally then wrap in clear tarp.
Use bicycle inner-tube or similar material to attach the door to the framing. The inner-tube also acts as hinging.