DIY Greenhouse

Back in 2016 we decided to get into horticulture a bit by building a greenhouse.  Of course this would be nothing like the massive greenhouses in our area, (check out a Google Earth of Leamington, Ontario) just big enough to house some of our various pepper varieties, some novel heat loving crops and harden off our propagation early in the spring when it comes up from the safety of the basement before being put out into the gardens.

We decided on an area of 10' X 20' at 8' tall at the center peak with a budget of less then $1,000.


List Of  Supplies:

Chain-link fence top rail bent by hand with EMT(Electrical Metallic Tubing) cross bracing
Double layer of 7mil greenhouse plastic off cuts from a local greenhouse supply store
Channel and wiggle wire
2 screen doors that were gifted to us
2x6 foundation anchored by buried 4x4 posts
2x4 wooden growing benches
Reclaimed industrial landscape fabric for a floor
Enough nuts, bolts and nails to hold it all together

We chose a spot towards the east side of the property and marked the area by spraying a 10' X 20' rectangle with herbicide, waited for it to start killing the grass, then mowed it very short.

 

The Process:

 

Sink twelve 4' long 4"x 4" posts 3 1/2' in the ground along the perimeter of greenhouse rectangle, screw 2"x 6" x 10's to posts.

Make wooden pipe bending jig and screw it to tree stump. (you are going to have to be creative with this one)
 

With the wooden pipe bending jig, figure out how to curve two 10' chain link top rails with a Gothic Peak so the screen door frames fit height/width wise while maintaining a 10' width at the base of the  greenhouse.
 

 

Hand bend the other eight chain link rails so they are all the same curvature. This has to be done visually and will probably be the most tedious task of the whole project. 

 

 

Predrill holes and connect the arches with carriage bolts to 2x6 foundations.

Bolt peaks of all arches to common 1 1/2 inch top rail and bolt 1 1/2 inch top rails a third of the way up side wall and use 1/2 inch EMT 2/3rds of the way up (for hanging plant supports from).

 

Diagonally brace side walls with 1/2 inch EMT and cross brace top of each arch with some more 1/2 inch EMT.

 

Build end walls out of 2x4s with screen door frames and room for plenty of ventilation. You can cover vents up later if you need to though its difficult to build in more ventilation later.

Cover ventilation with galvanized 1/2" wire mesh.  Install screen doors.  Round off any sharp corners that may damage plastic.

Install channel along bottom of greenhouse foundation.  Drape plastic over greenhouse, secure one long side with wiggle wire in channel, pull tight and secure second side with wiggle wire in channel. Do this on a moderate temperature day so the plastic doesn't get too loose when it gets hotter or too tight when it gets colder out.

Pull plastic neat and tight over end walls and secure by screwing wood slats over plastic.

 

 

Install 3/4 inch foam  (secured with double sided tape) on outside of plastic over each horizontal support to help provide air gap between this and next layer of plastic.

Drape second layer of plastic over greenhouse and secure in the same fashion as first layer.

Cover dirt floor with two layers of industrial landscape fabric.

Build four 8' x 2' wooden growing benches out of 2x6 frame and 2x4 slats.

Buy lots of terra cotta pots for growing in, cover hole in bottom with small square of cheap pot scrubber and fill with garden soil mixed with peat moss

Plant seeds. Water and fertilize as you watch them grow!

Hang yellow sticky cards to monitor pest pressures.

Have a couple of bowls of sulphur in the greenhouse to help with powdery mildew.

Install a fan to help move air around the interior of the greenhouse.

Install T5 high output fluorescent lights after installing electricity

The past couple of years we have planted a few different plants in our greenhouse. Our greatest success has been with many varieties of hot peppers and pickles, where bell peppers and poblanos don't seem to do as well.

This greenhouse seems to do well from early April to mid December.  Very hot days are fine as long as there is a breeze out of the East or West, and the greenhouse is relatively warm even into early winter as long as the sun is shining.