Stimey's Inexpensive Greenhouses

OK guys I am going to do my best to step you through the construction of these frames.... if you have any questions just let me know.

Step 1) build the base using 2"X8's -- join the boards together with splice plates (see picture under step 2)   (avoid treated wood since you will be using this for growing food)

step 2 ) secure base in place with conduit stakes

step 3) make the bows using 10' joints of  3/4" conduit

This is the only step that requires a special tool that most people don't keep around the house -- it is a conduit bender and will be used to bend the bottom portion of the conduit bow so that it can be secured to the base.

For a 12 foot wide structure you will need to cut the conduit to 106" - for a 14 wide house you will use a full 10' joint. The best way to cut rigid conduit is with a chop saw fitted with a metal cutting blade just make sure to wear goggles as sparks will fly.   To form the bend for the bottom of the bow measure up 8" and mark with a sharpie.  Slide the conduit into the bender where the 8" mark lines up with the bending point of the tool.  Slowly pull the bender towards you until you have created a 30 degree bend.  (This does not have to be precise just close).  You will need to make two of these for each bow:

Join the two pieces of conduit that you bent with a 90 degree elbow ( these can be purchased already bent ). Make sure to face the screws to the inside of the frame to avoid damaging the plastic once the greenhouse is covered. 

Step 4) Secure the bows to the frame on 4' centers using 3/4 conduit clamps.   --> see picture under step 2

Install all bows on 4' centers to desired length of greenhouse.

Step 5) Construct end walls:

Secure 2x4's to the end bow with galvanized pipe strapping (comes in rolls / cut to required length.) The 2x4's provide a nailer for the what ever type of siding you choose to cover the front and end walls.  The 2x4 is also used to secure the plastic cover to using furring strips.

Step 6) install purlins

Purlins are straight joints of conduit that run down each side of bows to provide support and to keep the bows from rocking back and forth. Use the 3/4 connectors to join the purlin together.  Attach the ends of the purlins to both the front and end walls.

Secure each bow to purlin using 6" adjustable pipe clamp.  After securing all bows wrap duct tape around the straps to protect the plastic cover from getting tore.

Stabilize and level the end walls:

Cut a piece of conduit 40" and flatted out bout ends with a hammer..... drill holes in the flattened ends and attach one end to the base and the other end to the wall. Use a level to level the end walls as you secure the conduit stabilizer.

You should end up with a frame that looks like this:

Now you are ready to cover the frame with greenhouse film (plastic).  You will need 20' wide sheeting to cover a 12' wide frame this gives you some extra to play with.   You can also cover a 14' wide house but you will have very little play when securing the plastic to the base. I use 1/2" furring strips to secure the film to the frame.  You will need an extra hand when covering the house as you will need pull the sheeting as tightly as possible.

Don't try to cover the house if it is windy... it is almost impossible to manage a large sheet of plastic in even light winds.  I do not recommend contractor grade plastic that you find at Lowes or Home Depot.  Between the wind and the sun contractor grade plastic will not last 6 months.  Purchase greenhouse grade plastic or as it known in the industry greenhouse UV film.  Greenhouse film is rated for 5 years and I usually get 8 years out of it.

In late spring through late fall I roll the sides of plastic up to provide ventalation. It gets very hot on sunny day even when the temps outside are cool.  On a sunny day in March with outside temps in the lower 50's the inside temp will quickly reach 90 - 100 if not vented.

During the spring I roll up one side during the day and then close the house back up in the evening.  I secure the rolled up plastic with spring clamps.

You can grow year around in these houses without heat.  You will just have to select crops that tolerate cool temps.  The economics behind growing heat loving vegetable plants such as tomato, cucumbers and peppers in the winter just does not make sense.  You will spend hundreds of dollars in fuel to produce $50 worth of food.... not to mention that since there are no bugs to pollinate you will have to do so by hand.   I grow the following crops in soil filled cold frames that are inside the greenhouse structure and in pots ranging from 1 gallon to 30 gallon.  Crops grown in a cold frame that is inside the greenhouse have the advantage of 7-10 degree warmer night time temps..... kind of like a greenhouse inside of a greenhouse.  I build my cold frames so that they can be broken down in the spring to give me more room for larger pots during spring and summer.

Early Fall:  To extend the summer season I move some pot grown vegetables into a covered house: peppers tomatoes eggplants

Late Fall:   lettuce, cabbage, mustard greens, green onions, carrots, new potatoes, broccoli, baby spinach

Early winter: same as above with the exception of potatoes

Dead winter - January - harvest anything that is left and prepare for early spring... we usually have temps below zero in Jan

Late winter - I sow seeds for upcoming seasons in a germination box ( see next page for details)

Early spring - same as late fall plus cauliflower, collards, beets, turnips

Mid spring - I get a head start on all summer crops by potting seedlings from the germination box  into 1 and 2 gallon containers.  I usually have blooming tomato and pepper plants by mid may which is our average last frost date.   Most people in my area plant their gardens around May 10th so by this time I am a month ahead of the normal growing season.

I use the greenhouse during the summer for container grown vegetables.  I grow most anything you can think of with the exception of corn in containers.

Some vegetable varieties are do better in containers than others. If you would like a list of the best varities that I have found down through the years just let me know.    ;)

Click here for details on the germination box