Thursday, June 11, 2015

Between a cold frame and a green house




For the last few years, my friend Tony Barton has tried to come up with a design for something like a greenhouse or cold frame, in order to extend the gardening season. He wanted it to be inexpensive and simple to build as well as portable. After experimenting for a while, he eventually came up with this hoop house which answers all his requirements.

Hoop house




I wanted to built one for myself but, not having the equipment to drill the required holes in the wooden base (see below), Tony volunteered to help me with these.  Then,on second thought, he decided to give me one of his, since over the last few years he has built several and cannot use them all!

The design is very simple. At the base is a rectangle of rough-cut cedar. Holes have been drilled on the long sides of that wooden base to accommodate the end of PVC pipes which are bent over the frame to make a hoop. 
The end of each hoop fits in a piece of rough cedar timber


You do not need straps to hold the PVC pipes, neither do you need any connecting joints as each rib is made up of a single 10 foot PVC piece. There is a small board at the top inside to which the hoops/pipes are tied to keep them in place with respect to one another.
Board at the top keeps the hoops evenly spaced

 The whole thing is covered with plastic, except for an opening at each end covered with a piece of plywood that acts as a door and a vent.  It does not need hinges or latches. At this time of the year, the "door" is open in day time and on sunny days the inside temperature remains around 30 C with one door/vent open.


It is not particularly elegant, but it is most useful and practical.

Like greenhouses and cold frames it allows you to extend the gardening season or to grow things that require more heat than you normally get. In my case I can use it in summer to grow crops for which the garden is not hot enough. It also allows you to grow greens earlier and later in the season. 
Basil seedlings grown directly in the ground

Plants are grown directly in the ground in the hoop house. My cold frame and the shed with a translucent roof I use as a green house have floors made of stones and gravel, and plants in them have to be grown in pots. 

 
Plants are grown in containers in the cold frame

The whole hoop house can easily be moved by two people. Being built of cedar and PVC, it is very light, even if it is big and stable enough to stay put in a strong wind. The possibility of moving it is important to me, because once it is set in once place for a season, I put a lot of compost and improve the soil inside it as much as I can. Then the next year I move it to a different spot in the garden where in turn the soil gets improved. 

It is not as large as a greenhouse, but bigger than a cold frame. This means that the volume of air inside it heats up and cools down less fast than in a cold frame and faster than a greenhouse. It seems a happy medium for what I use it for. It measures 4 by 8 feet and costs about $150 to build. It is in its 3rd year. I expect to have to change the plastic covering next spring. The only drawback I find is that it is not high enough to stand up in it (someone suggested it was, in fact, a stoop house).



14 comments:

  1. What a clever idea. I wonder if you could get the extra two feet of height without compromising stability?

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    1. If I am not mistaken, the problem is getting pipes that are longer than 10 feet.

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  2. Very nice. I have a commercially purchased small greenhouse like this. We set it up last year, but it was kind of a hassle to set up and take down. So, this year I used a simple coldframe that was much easier to maneuver. Sounds like yours is easy to use, too!

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    1. It sound very nice but why do you have to take it down once it is assembled?

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  3. What a good idea, it will be so useful, are you able to water the plants in there without having to get in yourself?

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    1. You have hit the nail on the head Pauline. You have to get in to water in the middle.

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  4. My purchased mini tunnel has the same problem in that it is definitely a "stoop house", having used it for several years, including one recovering, I have now bought a new one which being on special offer cost £80.00, this is 6'x10' the same size as the last one but has a headroom of well over 6' so hopefully I will not have to stoop any more.

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    1. To me £80.00 sounds very inexpensive. Here you can get a green house of that size ( 6'x10') made of rigid plastic and metal but it costs about $1000. I have a shed of a similar size that has a clear roof and windows on 3 sides. I use it mostly when nights are still cold in the spring.

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    2. The one I have is portable and is just a shaped plastic covering, including zipped doors and windows over a lightweight tubular frame, you bury or weigh down the edge of the covering although guy ropes are also supplied. It is cheap and cheerful but I will get probably 3/4 years use before having to buy a new cover.

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  5. Do you have commercial polytunnels which are similar but maybe flimsier,

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  6. This certainly seems very useful to you Alain and from your descriptions it certainly sounds far sturdier than some of the light weight ones I've seen for sale here.
    I wonder if re the water there was some way you could suspend a length of hose (with drip holes) along the length of the wooden baton. Possibly threaded through some sort of eyelet similar to that you can buy for hanging poles inside wardrobes. Probably impractical but just something that came to my mind as I was reading.

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  7. So resourceful and how kind of Tony to share. It looks like an excellent set up. :o)

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  8. Sounds great, really useful.

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  9. Hello Alain, we call these polytunnels, they're widely known here, both in domestic gardens and commercial growing.

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