Best Greenhouse Kits for Backyard Gardening

Editor’s Note: This is an updated and revised edition for 2018.

There are a ton of greenhouse kits available on the market but like everything else: which one is best for you?

There is a lot more that goes into choosing a greenhouse beyond its price. As mentioned in an earlier blog, a greenhouse is a tool and its features are what define its ability to do that job. In this blog, we discuss how to choose a greenhouse kit and the considerations that go into that process.

Considerations for Picking the Best Greenhouse for Your Project

There are many considerations but the first should always be about what you need the greenhouse to do. For some of us, that means standing up to -40°F for a few months. For others, it might be about lighting and landscaping. Here is a closer look at what all of this means.

The basics:

Greenhouses should at the bare minimum do two things:

  • Help manage adverse temperatures
  • Help Create a positive growing climate for whatever you are growing.

A greenhouse should be designed or if you are buying a kit, made for the type of climate where its installation will occur. Even though we call them all greenhouses, they are vast differences between one type of greenhouse and the next. Think about this in terms of differences in climate and how you’d dress for each season. Your greenhouse has to be adaptable for your entire climate.

A good example of these differences is a winter in Montana and one in Arizona – Still winter, but vastly different. Buildings in different areas and even in microclimates face different challenges and any greenhouse that you erect must face those challenges for years.

Creating an Atmosphere

People think about greenhouses as just having glass or plastic shells, but there are much more than just a shell. The shell is part of a system that creates the exact type of environment inside. The parts of a greenhouse on which to focus are:

The frame – Must be strong enough to stand up to snowfall – even in places where you rarely get snowfall. Snow is water and water weighs 8.33 pounds per gallon. Even across a small 10×10 span, snow adds up to a lot of weight quickly. It only snows here on occasion and we have a shade house that has bent rafters because one year it snowed four inches.

That unit has hollow steel tubing but it did not have the right supports to handle just four inches of snow. The key, in this case, was not the steel frame, but the support system that held it together.

In addition to the steel frame and the supports, you can design the roof’s pitch so that snow slides off rather than sticks – Think alpine housing design.

So, in places where the winter is harsh the best greenhouse kit is one that offers a design that will stand up to the weight of the snow and likely one that has a steeply pitched roof with a steel frame and plenty of frame supports. In addition, such a greenhouse needs to have a covering that allows in as much natural light was possible while preventing heat bleed-off.

In a tropical environment, it is water in its liquid state that is the danger. The roof needs to be pitched enough that rain and condensation roll off the unit before it can accumulate. The other danger here is the high heat. These types of greenhouses are often used to create a constant humidity or to recreate a humid environment where one does not exist.

Inside Features of The Best Greenhouse Kits

If you think about seasonal change, then the two things that change the most are the amount of available light (longer days or shorter days) and the temperature ranges. Plants each have a specific amount of light that they need and a range of temperatures in which they can survive.

More importantly, plants have an optimal range of light and temperature where they thrive. This is the sweet spot when you use a greenhouse and it should become one of your goals

What this means is you must plan for heating, moisture/humidity control, and lighting.

Best Greenhouse Kits – Small

Palram Snap & Grow 8

It has 3.5-star rating on Amazon but read through the reviews. It’s a solid building and the manufacturer offers additional sizes. One of the biggest complaints is about the difficulty in putting the unit together.

If you have trouble building a solid garden shed then installing a sturdy greenhouse is going to be a challenge. If you want the ease of a snap together kit, it probably won’t last.

This unit comes with gutters and there is an option for installing downspouts. That means the floor of your greenhouse, if elevated, is not going to turn into a quagmire of mud during the rainy season.

Another plus is that the panels are made of thick Polycarbonate and they fit into a slot system with added hardware to hold them in place. The should do just fine in wind. In terms of lighting the polycarbonate allows in 90 percent of incoming solar radiation and blocks 100 percent of the harmful UV rays.

What You Will Need to Add:

  • A heating system – There is a mechanical vent in the roof to help with both moisture and temperature control.
  • A Humidity System – You get plenty of protection from the elements, including wind and snow, but you are on your own when it comes to creating specific environments.
  • Should be attached to a solid surface, such as wood, and comes with flashing that allows you to do so. This is part of the design that helps deal with wind issues.

The largest model that this manufacturer offers is , which is plenty big. The 8x8x9 has a 6’8″ clearance for those of who are tall, and plenty of space for growing.

The question you must ask yourself is: how will you use a greenhouse and is 68 square feet going to get the job done?

One last plus that I love about this unit is that it is under $1,000. That means you can add a second one later if you need. Comes with a 5-year warranty.

Grandio Elite 8x12 Greenhouse Kit- 10mm Twin-Wall Polycarbonate

The Grandio Elite 8×12 has a solid 3-star review on Amazon. Reading through the ratings, I have to point out again that if you cannot build a simple garden shed, then this project is going to be difficult.

For many of the ratings, I think that construction was an issue. These are not an entertainment system from IKEA. It comes with a 10-year guarantee and that is hard to find anywhere.

Pros:

  • 10mm polycarbonate walls (twin panels.) 100 percent UV protection
  • Rain gutters – perfect for adapting to a water storage system and to shuttle water away from your greenhouse’s foundation.
  • Snow Load kit – fits many climates from dry and cold to heavy snowfall.
  • 8-feet of headroom
  • 3-roof vents – better control over temperature and humidity
  • 10-year panel warranty with a lifetime warranty for the frame.

Cons:

  • $2,500, which is about $1,500 more than the Palram unit.
  • Requires building experience even though the kit is 100 percent contained.

This greenhouse needs a foundation or elevated flooring. It is small enough to be toppled in the wind without securing it to the floor. It is a good base unit but will need a heating system if plants are to withstand cold. That is a very standard set of needs from these basic kits.

These two units are similar and really should be the standard for expectations for a basic greenhouse system. Out here, we built our own and built them to the standards required 1) for the types of plants we grow, and 2) to fit perfectly into all four seasons (we usually just have summer and winter) so that we have 100 percent control over the growing environment.

Choosing a Greenhouse

When choosing a greenhouse, it is important to realize that it is difficult to find one that will fit your situation 100 percent of the time.

These are artificial environments and to manage them you will need to be able to manipulate the inner environment to meet your growing goals. Really sit down and do your homework. Think about:

  1. What your growing goals are and as you do make a list that ranges from your basic needs to your wildest dreams. I have a friend who supplements his income by growing orchids and another friend who uses his greenhouses (plural) for growing bonsais. There can be room for more than just starting seedlings and part of being a prepper is being able to take advantage of everything at your disposal.
  2. Map out your climate and focus on microclimates. Technically, I live in zone 9b but in reality, I live in zone 7a – It gets that cold here. That is not information that I found online. It is information I found out about by talking to the older folk in the area.
  3. Focus on what you are growing and the specific environments needed for those goals. Then develop a list of plants that also grow in that environment. This helps you to maximize your growing options.
  4. Add a second greenhouse if you need a second type of environment.

So, which is the best greenhouse kit for you? That answer depends on how you answer the above four points.

Hit the comments with your questions.


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  1. I suggest Gardeners Supply Company for a wide range of styles/prices of greenhouses. We built a 20×24′ from them about 5 years ago and have found it an excellent bldg. Very stout and has actually been thru several tree toppling storms without a speck of damage. My husband and I put it up ourselves with the excellent directions they send.

    Another choice is Farm-Tek who have all sizes from hobby to commercial. Also sell the fabulous wiggle wire that runs in a channel around the bottom of your house and holds the plastic tight. No more staples. We installed it and haven’t had to do a thing to our plastic since.

    Finally, more than anything you need good ventilation in a greenhouse so don’t skimp on this

  2. May I suggest Harbor Freight, (and yes, this is made west of Hawaii).
    They have two different sizes of aluminum / plexy greenhouse’s. I looked at the large size approx 12′ x 16′ around $549 if I remember (and there are always coupons in many magazines, newspapers and the sales fliers for HF)…
    My only concern was snow load, so the salesman and I figured out to maybe add a cross piece halfway up the roof panel and if needed, even adding a thicker piece of plexy glass above the original panels and screwing them down to the extruded aluminum frame (pre-drilling them first of course.)
    I’ve looked at this unit 3 times now but have not actually bought it yet so this is all speculative…
    I’ll give you more feedback this fall, but in the meantime… go on down to the nearest Harbor Freight and check one out. One of these may be just right for you and again…under $600 and under $500 for the smaller house ( I have no affiliation with HF, just a customer when I want very, very cheap stuff.)

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