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How to Build A Raised Bed Greenhouse

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How to Build An Insulated, Raised-Bed Green House

Check Out The Building Plans Below!

Build the Raised-Bed Greenhouse shown on the right with just a few tools and inexpensive materials!  This greenhouse is designed for the cold, short growing seasons of the northern regions.  It is insulated and built upon a raised bed about two feet above grade.

Click on image for larger view of this Greenhouse

This Greenhouse Plan is only one design of many possibilities to grow your own!  If you would like to replicate it, follow the simple directions below.


Material List:

  • Three Sheets of 2" hard insulation; 4' x 8'
  • Six Fence Posts: 4" x 4" x 8'
  • Two Treated Boards: 2 x 6 x 10'
  • Two Treated Boards: 2 x 4 x 10'
  • Eight Treated Boards: 2 x 4 x 8'
  • Four Treated Boards: 1 x 3 x 10'
  • 1/2" Treated Plywood:  2' x 2'
  • Four Metal Corner Brackets for the door
  • Two Hinges for the door
  • One Roll of Six Mil Plastic:  20' x 24'
  • Galvanized Framing Spikes :  Half pound
  • Galvanized Screws 1 5/8":  One pound
  • Four yards of clay dirt
  • Two yards of top soil
  • Four yards of gravel

Step 1, Prepare Site  - Select a spot 8' x 12' that receives sun most of the day.  Stake out the ground and level it at ground level using a straight board and level.

Step 2, Post Placement - Select 4 x 8, Two" Insulated Foam material;  layout the six, 4" x 4" holes in the foam per the diagram above (Notice the center piece is different from the two ends).  Position the three foam sheets on the leveled ground, check for level; mark the six holes with paint or a stick.  Move the foam sheets to the side and dig six holes to the depth of 24" each.  Beginning at one end, place one end piece of foam, install the two posts; plumb and level each post and secure in place with bracing; then, backfill with clay dirt or "Quickcrete" cement.

Set guide strings in place using the two set posts as benchmarks.  Position the middle foam sheet and two posts followed by the end section using the guide strings to set the remaining posts.  Even all straight posts to 6' above the foam.


Step 3, Cover the Insulation - Cover the foam insulation panels with a minimum of 18" of clay soil or soil with heavy compost that will hold moisture.

Step 4, Build and Install the Top Frame - Select four, 2 x 4 x 8's; at one end, use two pieces as cross bracing.  On one side, use two pieces as side bracing as shown above.

Select one, 2 x 6 x 10, rip it in half (each piece equals 2 3/4"); each piece will be used as the top frame outer edges.  Select two, 2 x 4 x 8' for Left/Right edges; cut them to 6'; lay them out onto a flat surface to form the rectangle outer frame as shown above and nail them together with framing spikes.

Select the other 2 x 6 x 10 and position at midpoint as shown above, and nail into place; this higher board will allow the water to drain from the roof.

Select two, 2 x 4 x 10's and position them equally spaced as shown above, and nail into place.

Select the 1/2" piece of treated plywood; cut it into four, equal-sized right triangles; Turn the Top Frame over so the flat bottom is facing up; square the Top Frame, place the triangles into place and secure them with 1 5/8" screws as shown above.

Turn the Top Frame over again so the frame is resting upon the four triangles.  Select a 2 x 4 x 8'; cut to size the four pieces for cross-bracing; nail them in place as shown above.  Use a belt sander to smooth off and taper all the rough edges.

With some help, carry the Top Frame to the Greenhouse location, place the Top onto the six level posts, line up the edges, and secure the Top to the posts using framing spikes through the plywood into the posts.

Step 5, Build Door Frame and Door- Select 2 x 4 x 8'; measure the opening of the door end, and cut it to fit as the Base Plate; level and toe nail the Base plate into place as shown above.

Select four, 2 x 4 x 8'; measure the height from the Base Plate to the Top Plate; cut the four pieces to fit, ensure they are plumb, and toe nail the Door Opening Frame Supports in place as shown above.

Select one, 2 x 4 x 8'; rip it in half to make 2 x 2's for the door frame; use metal, corner support brackets for the corners of the door.  Build your door to the size of the opening, allowing for a 1/8" clearance all around; add a crossing support to keep the door square.  Cover the door with six mil plastic (use furring strips to keep the plastic in place).  Use two external hinges to hang the door; attach a latch to open and close.  Also cut and add door stops around the perimeter of the door frame.

Step 6, Cover With Plastic- Select the six mil plastic and cover the entire structure (there should be at least 12" excess on all four sides; gather and attach to the corner posts using 1 x 3 furring strips;  Add dirt and gravel around the perimeter on top of the excess plastic to keep the greenhouse air tight.

Step 7, Plant Seeds - Add some top soil and mulch, select the seeds of choice and plant; add some water and a thermometer to monitor a mild temperature and moisture content.  If the temps get too high during a sunny day, allow the door to remain open so the plants do not become over-heated.  Once the plants become semi-mature, and the night-time temps consistently remain above 50, the plastic can be removed and stored away for next spring.  The plants will continue to grow in their environment.  For those in the northern climates, this system will add 30-60 days to your growing seasons.  Adding a heat source and artificial light can only improve your growing successes.

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