PlanterTomato Vegetable Gardening

Buying An Economy Greenhouse (Assembly & Recommendations)

In my prior posting, I described how I came to purchase an economy greenhouse kit.  In this posting, I will address what is required to build the kit and make recommendations to those considering a similar purchase.

Assembly

The Kensington Greenhouse Kit is comprised of three principle components: hollow aluminum frame components, metal connectors, and polycarbonate panels.

The way one constructs the greenhouse is by connecting the appropriate frame components using the connectors supplied with the kit; you slide one end of the connector into the hollow end of one side of a metal frame until it clicks into place.  You then take a second frame component and slide it over the other end of the connector until it too clicks into place.  This links the two pieces together.

Repeat the process again and again and you slowly build the skeleton of the greenhouse.  The frames have channels along the edges.  One creates the  walls of the greenhouse by sliding the polycarbonate panels into these channels, which then hold the panels in place permanently.

Sound easy?  Not so fast!

The concept is simple, but the execution is far more complex. 

There are dozens of frame components and connectors.  For example, there are connectors that connect two components, connectors that connect three components, left facing connectors, right facing connectors, connectors that connect at 90 degrees, connectors that connect at 180 degrees, connectors that connect at other angles, etc.  You get the idea.

Likewise the frame components are of varying sizes, some with notches or holes that are required to be properly oriented so that they fit with other components.

To build the greenhouse, you must first separate what must be over 1,000 components and parts into 26 piles.  The piles represent individual stages of construction.

The sorting process alone will take several hours.  As boring as this is, it is absolutely essential that you do this, otherwise you will lose your mind trying to locate the correct parts during construction.

Additionally, all the aluminum frame components are wrapped in plastic which you will need to remove and dispose of.  When I built my kit, I did not realize that the polycarbonate panels were also covered on both sides with a Saran-Wrap-like protective plastic.  I built one side of the greenhouse before discovering this error.  I then had to disassemble the components, remove the plastic and rebuild 25% of the greenhouse.

I found the manual to be well written and to contain good illustrations.  However, I made a variety of mistakes along the way that required me to disassemble and reconnect frames and connectors. I am fairly certain that anyone building this kit for the first time will have a similar experience.

I also found it difficult to slide the polycarbonate into the channels of the frame components.  This would have been much easier on a perfectly flat surface, but I was doing my assembly on my lawn.  If you decide to build a kit greenhouse, I recommend building the sides of the greenhouse in your garage or driveway, if that is an option, and then transporting the sides to your backyard for final assembly.

The manufacturer said the kit would take two people a weekend to construct.  I built the greenhouse by myself in about 3.5 days of fairly intense labor.

Performance

I live in Northern California, which is zone 9.  I found that during our Fall and Winter months, the temperature in the greenhouse stayed 10-15 degrees Fahrenheit above the ambient temperature for several hours after sunset.

That was warm enough to allow me to grow cold tolerant vegetables such as chard, kale, bok choi, arugula, scallions and others without the use of additional lights or heat.

On warm days last Fall, I found it necessary to open the top vent and door in order to keep the greenhouse from becoming too hot.

While we are on the subject, the top vent is not well constructed.  On a windy day, the vent blew open and bent the aluminum frame in which it sits.  As a result, the vent no longer closes completely.

Conclusions and Recommendations

I'm very glad I have a greenhouse.  It has allowed me to harvest vegetables all winter long.  It will also give me a convenient place to start my seeds this spring.

However, building a greenhouse using an economy-grade kit is not as convenient as I would have hoped.  For me personally, the "juice was not worth the squeeze."  If I could turn back time, I would build my own greenhouse, even if it took longer to construct and cost more money to do so. 

Not everyone is willing to take on that kind of a challenge, so here is my opinion on who should consider purchasing an economy greenhouse kit:

Consider Buying If You:

• Are not handy and don't want to hammer, cut, nail, and do other building related tasks.
• Want to have a greenhouse that looks very professional at a low cost.
• Are patient and are willing to spend the time and energy required to build the kit.
• Live in a cold climate and just want to extend your season or start seeds.
• Live in a moderate climate like zone 8 or 9 and want to do winter gardening of cold tolerant vegetables without additional lights or heat.

Don't Buy If You:

• Are handy and want to build a greenhouse that to meets your specific growing requirements or design interests.
  
• Live in a cold climate and want to grow cold tolerant vegetables during the winter.  In my opinion, the insulation provided by an economy kit will not be sufficient.
• Live in a windy area.  The kit materials are not sufficiently strong to resist heavy storms.
• Do not have the physical stamina to do alot of bending or stretching that construction will require.

Your Experiences

If you have a greenhouse, please tell me about your experience by replying to this post as a comment below.

Buying An Economy Greenhouse

If you've are thinking about putting a greenhouse into your garden this year, this series of postings may be particularly interesting to you.  In this and in my next posting, I will describe buying, building and using an economy grade greenhouse.

If you are a first time buyer, shopping for a greenhouse is an eye opening experience.  When I stared searching, I had no preconceived ideas about the cost, and I quickly discovered that they are very expensive.  Even "economy" is expensive.

"Cha-Ching" Get Out Your Credit Card

An 8' x 10' Victorian-style glass greenhouse is $6,000.  These greenhouses are top-of-the-line in terms of construction, durability and looks.  But they are so far outside of what I had budgeted for this project, that I will only mention them as a way of providing you a sense of scale with regard to prices.

A good grade greenhouse of about the same size will be made of polycarbonate (clear plastic) panels, rather than glass, and the frame is often aluminum, rather than steel.  These can be purchased for $1,500-$2,000.  Much less expensive, but hardly cheap.

At the economy grade level, greenhouses are made with single ply polycarbonate and have light aluminum frames.  These can be purchased for under $1,000 from a variety of online sellers and from Costco.

After looking at thee various options, I gave serious consideration to building my own greenhouse.  But as I investigated further, I discovered a stumbling block.

Building A Greenhouse

If you are going to build your own, you will need to find a source for polycarbonate sheets.  Polygal is an excellent brand and they have a product line designed specifically for agricultural use.

Polygal sheets transmit a high degree of light, are UV protected so they resist cracking and discoloring in the sun, and they come in a range of thicknesses (6mm-16mm) which provide more or less insulation depending on the needs of your climate.

It's my personal philosophy that if you are going to go through the trouble of building your own, the best approach is to use highest grade materials you can because you are going to make a major investment in the project in the form of your own labor.  Great materials pay back this investment over time.

And here lies the problem... Polygal is not distributed at home centers like Lowes or Home Depot.  I could not find a local supplier, and my only other option was to buy it online and have it shipped to me.  The online supplier requires that orders be crated for shipment and the cost of the cost of this alone was several hundred dollars.  Ouch!

Buying A Kit

Given the high cost of shipping, I opted to buy a kit greenhouse.  I reasoned that this was the best option for me after weighing the following considerations:

The Positives

• All materials in one box.
• Less labor than "Do It Yourself."
  
• A low price relative to other options.
• Professional appearance - looks like a more expensive greenhouse.
  

The Negatives

• Lower quality materials in general.
• Single-ply polycarbonate found in economy kits provides minimal insulation.
  
• No option to customize design features.

I purchased my kit from Costco; the "Kensington" greenhouse kit set me back $600 after my $150 rebate.  The kit provides single ply polycarbonate panels (not better grade Polygal), aluminum frames, and all the hardware you need to build the greenhouse.  No special tools are required.

The Kensington Kit is not a regularly featured item at Costco; you order it from Costco's web site, and it is delivered to your door via UPS Ground Service. 

In my next posting, I will describe what it's like to build this kit.  I will also make specific recommendations to gardeners based on my experience using the greenhouse over the fall and winter months.

See you next post.