Posted by: iainduncani | March 12, 2011

Making a mini-polytunnel

When we moved into our house and I saw we had bamboo growing I was a little worried. A friend of ours had bamboo in his garden and said it was an absolute nightmare, spreading all over the garden and blunting his lawn mower. We must have a different variety though as its stayed in place and has proved a great building material for various garden projects – the latest one being a home made mini-polytunnel (or if you are fan of oxymorons a tunnel cloche).

Bamboo bent and tied into loops

Figure 1: Bamboo bent and tied into loops

The nice thing about growing your own bamboo is that you can shape it whist it is still green and malleable. Unlike other home made polytunnels that bend two shop brought canes together with hose pipe to connect them into a loopI bent my cane as soon as I harvested it, tied it up and left it out in the sun to dry for a few weeks (see figure 1). This meant that I had a single smooth loop to work with.

I selected two loops of a similar size and used 4 straight canes to make a rectangular base. I then tied the two loops to each end of the base using garden twine.

The next step was putting some polythene sheet that I got from a local garden centre over the top. I fixed it by wrapping it under the base and around the supports and tieing it on using some galvanised steel wire that I had left over from making raspberry supports (see figure 2). I wanted the tunnel to last a couple of seasons so I was worried the polythene would tear where the wire went through so on most of the ties I first stuck down some parcel tape to hopefully stop the tearing. Not sure how necessary this was and it does make it look a little messy so I’m not sure I’d do this again.

Figure 2: Bamboo loop tied to the base with polythene attached by some wire

Figure 2: Bamboo loop tied to the base with polythene attached by some wire

Reading around there are two concerns about polytunnels, the first is wind knocking it over and the second is ventilation. Bamboo really helped with both of these. Even with the fresh bamboo it was impossible to bend it into a complete circle so this means that the loops had long legs on them. I didn’t cut them down too small so this means that they can act as stabilisers when they are buried into the ground. As there is about a foot of cane underground I’m hoping this will be enough to stop it being blown over.

The low feet also allows me to raise up the polytunnel on hot days to give some ventilation. Even with the feet just half buried it still seems pretty stable but allows air to get underneath (see figure 3).

Figure 3: Finished polytunnel raised up slightly for ventilation

Figure 3: Finished polytunnel raised up slightly for ventilation

I’ve had it out on the veggie bed for a week now and its still not blown over! The one thing that I may do another time is to put an extra straight cane across the top to stop it sagging inwards although again I think the long feet help with this as they stop the ends toppling over at all.

Advertisements

Responses

  1. […] bent the bamboo in the same way I did for my mini-polytunnel I then screwed two planks of treated wood into the wall, one on each side of the doorway. I then […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Categories

%d bloggers like this: