2015: Greenhouse Plans

After the failure of the brussel sprouts from cold, dealing with garden pests, over watering due to rain, and limited production from the garden, I started 2015 with the goal of building a greenhouse to house all of my family's plants.

I started by first laying plastic down where I wanted the greenhouse to be. Plastic helps kill the grass and reduce the location for bugs to dwell. I used black plastic which heated up well from the sun (further making the place inhospitable), plus it was also cheap. It also directed rainwater away from the garden. It had the added benefit of providing a surface to walk on that did not create mud. I found that the plastic was not slippery either because it had a tendency to deform to match footprints (sort of like stepping on foam flooring).

Then I started to plan my greenhouse.

Criteria:

1. cheap enough for my budget
2. easily removable if I need to move (no foundation or solid building)
3. fit whatever housing codes

This narrowed my selection down to the following kinds (that I was able to research):

1. PVC hoophouse
2. disposable grow house
3. plastic tent
4. Some combination

Pros and Cons PVC Hoophouse

PVC Hoophouses are greenhouses made with plastic and PVC piping that is bent to form an arc similar to how old military tin quansot-huts were built (think Gomer Pyle shown in this lunchbox from greatestcollectibles.com)

1. Pro: PVC hoophouses are cheaper than building with wood and clear plastic siding. Plastic sheeting ($42), tape ($10), 3/4" PVC piping (18x3=$56), PVC couplers (14x.28=$4), wood baseboards/support (8x8=$64), staples ($4), and screws ($4) can make a hoophouse that covers a 20x30 ft area for roughly $180. See the below diagram or how to build something similar at http://www.aces.edu/pubs/docs/A/ANR-1105/ANR-1105.pdf 
   
2. Con: Since I am using vertical farming methods, hoophouses have areas of dead space that reduces the amount of growing area based on the height of the vertical growth. This is intensified if the ground is sloping like in my backyard (See below diagram).  
   
   
   
   
3. Con: PVC warps in the sun or cannot support vertical weight on the top so the structure needs supports in the center to prevent collapse (See Example of a hoophouse in Connecticut. Source unknown).  Although not too big a deal based on the area that the support uses, it decreases the amount of growing area and affects the planting layout. It also adds to the price of construction. Or PVC cross bracing is added which also adds more costs.
   

Pros and Cons Disposable Grow House

1. Pro: Ready-made and easy to erect. If you notice in the images from previous posts, we already have one for seed starting. It is the same one shown from the below image from Pinterest.  
   
2. Con: To cover a 20x30 ft area, I would have to buy multiple ones which are cost prohibitive or find one at the same size area which would again be cost prohibitive.
3. Con: Multiple ones would have access and ventilation difficulties that I may not be able to solve without increasing costs.

Pros and Cons Plastic Tent

In this design, clothesline or heavy rope is used to strengthen the poles upright while the plastic is laid on top. Plastic can be stapled to the poles and staked to the ground. Clothesline is staked to the ground.

1. Pro: Plastic tent is the cheapest for the same given area. Plastic Sheeting ($40), clothesline made of plastic coated galvanized wire ($36), staples ($4), loop stakes ($10), 4x4x120 lumber ($24), and 2x4x96 lumber ($24) can make a plastic tent that covers a 20x30 ft area for roughly $138.  
   
2. Con: Areas of the roof may pool water which may be why it is not popular.
3. Con: Greater chance of plastic tearing.

Pros and Cons Combination (My Design)

In this design, I combined elements of the PVC hoophouse with the plastic tent. I wanted to add rigidity, and keep costs comparable. It almost serves as a lean-to with the poles as the main support and PVC serving as the frame strengthened by the clothesline. PVC T-couplings are used where the PVC frame meets the clothesline. PVC T-couplings are used where PVC frames intersect (it is not illustrated that way in the drawing). Below is a computer rendition of the hand drawing I had planned to submit for my building permit. It just needed dimensions added to be ready for review. Overall, I really wanted to build this style of greenhouse.

1. Pro: Construction cost is comparable.
2. Pro: Makes better use of land space as compared to a Hoophouse.
3. Pro: Less likely to have areas of roof where water may pool as compared to a plastic tent.
4. Pro: Compliments an earlier method of staggering plant heights.  
   
5. Con: Untested design.

Next: 2015: Greenhouse Building Permit