Here is How to Build A Greenhouse from Scratch

Greenhouse Materials List

  • 2″ x 12″ planks for sides of raised beds.  Redwood is recommended.
  • 2″ x  4″ lumber for top ridge beam, center frame, door, end framing and bracing between beds.
  • Steel T-type fenceposts to cut for staking beds against pressure.
  • 20′ x 1/2″ steel rebar for reinforcing hoops.
  • 20′ x 3/4″ PVC pipes for hoops.
  • 3/4″ metal pipe pipe hanger brackets with screws.
  • Sufficient 3-year rated, UV-resistant greenhouse plastic to cover length plus ends without seams.  A 10′ x 32′ greenhouse will require 50′ of 20′ wide material.  It will come in a 100′ roll, leaving enough to replace it after 3 years or to cover another one.
  • Rabbit or gopher wire and U-nails to protect beds from burrowing critters.
  • Soil mix to fill the beds.

Options:

To make the greenhouse shorter or longer, subtract or add hoops and planks.  Since the rebar, PVC pipe and plastic skin come in 20′ maximum lengths, the width of the greenhouse will be set at 10′ when the arch is 10′ high in the middle.  You can get wider floorspace by lowering the height and a taller greenhouse by narrowing the width.

If you do not need raised beds (for example, you want potting benches inside instead) make the frame out of all 2x4s with bracing going from one side to the other along the floor.

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Illustration 1

Construction:

  1. Construct wooden beds and frames on level ground (or else adjust by excavating and terracing).  Stake plank bed walls every 8 feet with a half of a sawed-off fence post.
  2. Fasten rabbit or gopher wire carefully not to leave gaps.
  3. Fill raised beds.
  4. Insert rebar into pipes on ground.
  5. Stand rebar/pipe up and secure the bottom end a little beneath the outer top edge of the side plank.  Screw securely.
  6. With some neighborly help, bend the hoop down over the top beam — it will form a perfect arch, but is under great tension in the final position.  Secure and do the others.  At both ends tack a nail on both sides of the pipe where it rests on the top beam, sinking the nails below the pipes’ top surface so as not to rip the plastic later.  The interior hoops do not require this.


Illustration 2

  1. Unroll plastic greenhouse skin being careful not to puncture or step on it.  Drape it over the greenhouse frame.  Begin at the center to fasten plastic to outer wall.  Cut lath strips just the right length to fit between the hoops with an inch away from them on either side to allow for plastic stretching.  Roll the plastic once or twice around the lathe strips toward the inside so rain will roll off.  Nail securely.  Be sure to roll and nail the edge evenly and stretch the skin as tight as possible sideways before securing skin edge.
  2. Next begin at the center on the other side.   Have your helper stretch the skin drum tight.  Work out from the center to each end.
  3. Take the loose ends and test-pull the top to determine how much to trim off to still have enough to roll in lath strips to fasten along the door top, but do not cut it yet.  Try the sides, likewise.  When you have the picture, mark with a laundry marker, trim the extra and find the appropriate spots to cut to make the lathe trim fit the square edges of the door and vent frames.  Pull drum tight.
  4. Fit doors and windows (vents) to ends.   Make them airtight, no leaks, since the efficiency of this greenhouse depends upon vapor tightness.


Illustration 3

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