Building the Ultimate Greenhouse

Congratulations on purchasing your new One Stop Gardens 10’ x 12’ Greenhouse!  Growing vegetables, cultivating flowers or starting your botany experiment is now close at hand but did you know that you can get even more out of your greenhouse with some extra time, materials and patience?  I recently came across a great article that highlights a few ways to expand your greenhouse in ways that you might not otherwise think of at http://hfgh10x12.blogspot.com/2007/08/this-is-greenhouse-we-bought-link-it.html.  Let’s take a look at how you can take your greenhouse to the next level with just a few adjustments.

The greenhouse kit comes with a steel base that you would generally just place on the ground.  The author of this article explains how to add some extra stability to your greenhouse in order to resist any weather conditions you may encounter like strong winds and heavy rain.  “The popular solution is to build a wooden foundation, anchor it into the ground somehow, and mount the steel base on top,” she says.  “Everyone finds their own way to do this, but most use at least 4 x 4 sized timbers for the base.”

You’ll also want to add a couple of diagonal beams at each corner before mounting the greenhouse base itself.  With your greenhouse secured to a foundation, you can keep the base square and tight for years to come.  And once you’ve got the steel base mounted to the wooden foundation, just apply some clear silicone caulk between the wood and the base to keep rain water from seeping in.  In order to maintain the integrity of you greenhouse, you’ll need to plan for all types of unforeseen weather and environmental conditions.  You can choose from a few different caulks on Harbor Freight’s website too, from Painter’s Acrylic Latex Caulk to Acrylic Latex Caulk plus Silicone.

Now you’re ready to start putting up the walls of your greenhouse.  The article has a little tip to keep your frame and posts straight during construction as well.  “As you put the corner posts up, temporarily attach the [included] diagonal braces for stability.”  You’ll have to remove them before moving on to the next step but this way you can work with a bit more peace of mind and keep the aluminum frame straight and accurate until you add the vertical wall studs.  It’s a good idea to check that the base is still square before moving on and make any necessary adjustments.  It’s much easier to make minor adjustments as you go rather than a big one later.

Once you’ve got the greenhouse frame constructed, there are a few things you can do to upgrade it for stability in windier areas.  The article advises to add horizontal braces at the tops of the walls to prevent the side walls from pulling away from each other.  You can do the same for the front and back walls.  Just attach a solid piece of material all the way across each wall to reinforce the structure and keep the elements from potentially warping the frame.  The author explains how you can also keep the steel base from flexing:  “This can be done by bolting small plates of some type to the top and bottom lip of the base at regular intervals, or by covering the inside of the base entirely with wood that's also attached to the top and bottom lip of the base.”

It’s also easy at this point to add insulation to your frame, she continues.  “We used ¾” thick expanded polystyrene (styrofoam) insulation, cut into strips about 4 ¼” wide. We also stuffed some foam sill insulation in there first to remove as many air pockets as possible.”  You can protect that insulation and further reinforce the base by attaching boards with screws to the top and bottom lips of the base.  As the author says, “Now the base is insulated and stiffened by the attached board...and it looks a little dressier, too.”

Well, at this point, you’ve got yourself an extra strong frame of a greenhouse and you’re ready to move on to inserting the panels.  The author of the article sealed the ends of each panel with aluminum tape to help keep dirt, condensation and bugs out.  “I bought one roll of 1 ½” wide aluminum tape (not duct tape) and cut it into thirds, so I only have a small taped rim visible on the panels.  On the bottom edge, it’s apparently good to have small holes in the tape to allow moisture to escape. You can buy special breathable tape from greenhouse supply websites for this purpose, but others have mentioned using a large pin to poke holes in the tape in each chamber on the bottom edge of each panel.”

How about weather stripping?  Well, the author has a suggestion for that as well.  “Instead of caulk, I used 3/16” thick closed cell foam weather stripping in each panel opening. Closed cell foam is waterproof so rain can’t soak in.”  The larger gaps on the tops and bottoms of each panel are also mentioned.  “I found some packages of ¾” wide weather stripping.  I used that, cutting each strip in half with scissors, so it was 3/8” wide. It worked fine and turned out to be a soft gray color that was hardly visible under the panels after installation.”

Okay!  So now that you’ve gotten your greenhouse constructed and ready to withstand those heavy winds, you’re ready to add even more awesomeness!  That’s right, there’s still more you can do to enhance the greenhouse to make it more attractive and convenient.  The author added long benches to each side of her greenhouse along with several peninsula-style benches.  “Each long side bench is supported by two pressure-treated 4x4s, buried 24" deep and set in concrete.  [Then] two horizontal Douglas Fir 4x4's were clamped to either side of the two pressure treated posts. The horizontal 4x4’s were attached by using a 12" long 3/8" drill bit to drill a hole through all three 4x4's. A length of 3/8" all-threads rod was inserted in the hole and capped on each end with a washer and nut.”  This addition will provide plenty of shelving space plus ample free space underneath for tools, equipment and supplies.

If you want to get really fancy, the author even added a sink to her greenhouse and explains how it can be used for added benefit.  “The sink drain isn’t connected to our house plumbing. It drains into a gravel pit we dug in the floor, and the soil beneath the gravel is the coarse sand of our yard. Another option for the future would be to route the drain water through the wall of the greenhouse and outdoors to water a planting bed.”

Still want more enhancements to your bodacious greenhouse?  The author of this article really decked hers out to include some pretty cool additions to improve functionality.  She added electrical outlets with plastic covers to keep out moisture, Aluminet shade cloth screen panels to keep temperatures down and even an exhaust fan as a way to let air out.  These are obviously more advanced enhancements but the possibilities are there for those willing to put in some extra work.  And for those hoping to use their greenhouse continuously, they can be a real help, as the author states, “Without this fan I wouldn't be able to keep plants in the greenhouse year round...our summers would be far too hot. With this fan in place, as well as some additional small fans for HAF (Horizontal Air Flow) and generous amounts of shade cloth, I'll have a fighting chance.”

As you can see, getting your Harbor Freight greenhouse built is only the beginning of your journey and you’re limited only by your imagination!  I don’t know about you but I would love to have benches, a sink, air conditioning and weather stripping in my little home garden.  For anyone who wants to get serious about their plants and flowers without spending serious money, this is the way to do it.