Greenhouse Effect
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2009 Edition

I reconstructed the greenhouse again for 2009 for the same purposes as before.  There were some improvements to the structure that are documented below.  Hopefully during 2010 I will build a permanent "garden house" in the yard that will serve as a more robust storage shed and greenhouse, and the need for this temporary structure will no longer exist.

There are three main differences with the 2009 edition of the greenhouse:

  1. 1.    I wanted to eliminate the use of wood altogether and simplify the design and
           construction, so PVC was used for all of the framing.

  2. 2.    I had more plants to put into the greenhouse this year, including some small trees.

  3. 3.    The greenhouse was moved to a location on the other side of the yard in order to
           capture just a little bit more morning sun.


Previously, using wood made construction of a door somewhat easier, and it allowed for affixing the sheeting with staples.  However, wood does not connect to PVC well, and it deteriorates quickly over time.  I wanted to create a consistent frame that was entirely PVC.

On paper, I designed what I thought would be a pretty nifty door that would be framed in PVC.  I also had to modify the two PVC arches to accept PVC all along the perimeter base.

Here, I employ a highly-refined, OSHA-approved sawhorse technique to shorten the PVC arches.
They had to be slightly shortened due to the addition of the couplings at each base.
Don't try handling a sawsall this way unless you are highly trained, or are an idiot.


In 2008, the plastic sheeting was stapled to the wooden bases, and also kinda pulled under the structure.  Over time this started to fail, as the plastic would pull away from the staples under wind pressure.  This year, I pulled the ends of the sheeting completely under the structure, then used weed fabric pins (or "yard staples", as I call them) to hold the plastic in place.  The pins, and the weight of the greenhouse should be enough to keep the plastic tight.

I use tape to reinforce the pin locations so the plastic will resist tearing.


The greenhouse is framed and the topsheet attached and anchored.  I was unable to reuse 2008's topsheet
 for this purpose as it was too well worn, though I did recycle most of it for other uses.   I did make a decision
that caused some difficulty and turned-out to probably not be necessary... I cut the front arch support in order
to place a vertical beam that I thought would be part of a door.  I went another direction which probably meant
that was unnecessary, and what it resulted in was creating two 8-foot half-arches (schedule 40 PVC)
that proved very difficult to bend into place.  You can see the couple at the apex, and the arch is a
little more pointed than round. 


Problem:  Autumn bringeth many leaves to dispose of......


Solution:  Insulation.

As I brought the plants into position, I packed them with the leaves from the yard.  This will hopefully accomplish several things:

  1. 1.    Storage of the leaves over the winter as I cut the new vegetable garden.  Later, I will 
           mulch the leaves and till them into the new garden soil.

  2. 2.    Stagnant, cold air around the roots of some of the potted plants is an enemy.  The 
           leaves should help guard from that, and trap more heat from the ground.

  3. 3.    While probably not significant, the leaves should start to decompose, and will 
           therefore give-off some heat in the process.


In packing the plants in, I stuffed a lot of leaves between pots and the plastic to still tighten the plastic over
the wireframe and make it just a little more resistant to "wind flapping".  When the wind starts playing on
un-taut or loose fabric, that fabric starts to act as a sail and slowly pulls the fabric away over time.  


So much for the wheeled cart I kept promising myself I would make over the summer.


I still had last year's straw bale handy.


As I often say, the best laid plans won't get you laid the way you planned.  So it was with the door.  The 2008 door structure -- with it's wooden frame, hinged door, and free-standing jambs -- was sloppy and leaky (though maybe good from a ventilation point of view).  I thought I could build a snazzy door totally from PVC, and went as far as to buy some special pipe and couplings.  That project just didn't go well, so I redesigned a simplified version mid-way through (like they do it at Hanford).  That just got superfluous, so I ended up with no real "door" at all and made a flap door.  It's a bit of a pain to get into the greenhouse, but it's "cleaner" and seals better.  I shouldn't actually have to go in there more than a dozen times throughout the winter anyway.

I just used Velcro tape along the arch support for closure.  It's good to have closure. 



In 2008, there weren't many plants for the space I had.  This year things are a little fuller because I have acquired more, and some of the things I intended to plant into the landscape over the year just never got planted.  That's okay because like those Emperor Penguins in Antarctica and like people they like to snuggle.

If anyone has plants they would like overwintered, let me know and we'll put 'em in here.

I have a variety of plants, including small trees and about 30 members of my cactus / yucca / succulent collection.

All cozy.  In the back, you may notice crossing black lines.  I used 48-inch bungee cords
to add just a little more stability to the back wall, which is one big sheet secured only at the
margins.  This wall faces into the prevailing winds, but of course we rarely get any wind here.


Some of these guys were in here last year.  They sure are patient with me.
Some day I'll get them in the ground.



After observations made in 2008, I moved the greenhouse from the northwest corner of the yard to the southwest corner.  It should get just slightly more sun in the morning hours as the sun wraps around the house, though may get more filtered sun later in the day due to the large sycamores in the neighbor's yard.

If you look closely, you may spot the bees back in the corner.


In-Situ Greenhouse

I also wanted to take an extra step to protect my fishhook barrel cactus in the rock garden.  It should withstand the cold alright, unless we were to have extended periods of extreme cold.  This plant's main enemy is winter water.  Since the ground stays cool here in the winter, and both drainage and evapotranspiration can be slow, plants like this can sit in damp ground for weeks and even months, and that usually kills them.  As such, I wanted to provide a little added cold protection, but mainly an umbrella to keep rain and snow off of the cactus and the immediate area around it.

First, I packed it with some insulation in the form of sycamore and yarrow leaves.


Next, two pieces of scrap plastic, secured with staples and a few rocks and you have instant greenhouse.
There are enough gaps as to allow for plenty of ventilation so it doesn't get too hot under there.
So there should neither be soggy cactus nor baked cactus come spring.


I hope you found this page useful, perhaps even a bit entertaining.


19 NOV 2009

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