4 Crucial Things to Ask When Buying a Greenhouse Kit

Small greenhouses kits are an excellent way to extend your growing season and create your own backyard oasis. Greenhouses capture energy in the form of heat, creating an ideal environment for growing vegetables and plants. Below are a few tips of info that will help you choose the best greenhouse kit for your backyard garden.

Things to Ask When Buying a Greenhouse Kit

  1. How long do I want my greenhouse to last? (this will determine the fabrication materials)

  2. What kind of ventilation and cooling will I need for my climate? (shade cloth, vents, louvres, fans)

  3. What is my budget? Am I willing to spend a little more to get something much better?

  4. Does the kit I'm buying have:

    • The frame I want (aluminum is typical)
    The covering I want (polycarbonate panels are virtually unbreakable)
    • The right ventilation and cooling for my climate
    • The room I need for the plants I want to grow (footprint, headspace, door access)
    • Shelves and/or benches (these create great additional space)
    • Hangers (trelissing kit, hooks)

Types of Greenhouse Kit Coverings

The most important to question to ask yourself is how long you want your greenhouse to last. This will immediately determine the type of covering and frame your small greenhouses kit will have. Different types of greenhouse materials have different lifetimes. There are three main types of materials used to cover a greenhouse.

Polyethylene Film

This material is the cheapest and shortest lasting material used to cover greenhouse frames. This material can usually be found for less than 10 cents per square foot and will usually need to be replaced within 1-4 years. Wind, falling branches, sharp objects all cause this material to easily rip. It increases interior humidity but has a low insulating value. The advantage is that it is economical and easy to replace.

Polycarbonate Panels

Polycarbonate panels have estimated costs of $1.00-$2.00 per square foot and is much tougher than polyethylene. Polycarbonate lets more light through than most other materials including glass. Due to its construction it has high insulation values and has a high impact resistance (hail!).

Polycarbonate usually has a lifespan of up to 15 years. Polycarbonate panels are easy to install and can be cut with snips or a knife. Ensure to find panels that are UV protected. These panels come in single and multi-wall varieties. The multi-wall panel provides additional insulation and impact resistance.

Glass Panels

Glass panels are the longest lasting but also the most expensive. Some manufacturers quote these panels from around $3.00-$7.00 and upwards depending on the quality.

Glass my be expensive but it does look good, and some of these small greenhouses kits can last for decades (25 years+). The disadvantage is that glass panels can be difficult to install and has a lower impact resistance than polycarbonate panels.

Types of Greenhouse Kit Frames

Below are some common types of greenhouse kit frames:

Aluminum Frames

Aluminum frames are long-lasting, light-weight, resistant to corrosion, and can come with various color finishes. Small greenhouses kits that are made from aluminum are often easy to put together and can be built within a day or two by the average person. They are also usually better at load bearing than plastic frames.

Plastic Frames

Plastic frames are the easiest to put together. If you buy a plastic framed small greenhouses kit, ensure that the plastic is UV treated. These types of frames have a typical lifespan of 5-10 years.

Wood Frames

Wood frames are typically used for one of two applications: either as an economical diy project, or for a rustic look. My father built 2x2 framed greenhouses on our farm when I was young. These were quick to build but were often buffeted by wind and could not resist much build up of snow.

Nice treated timber can be found to create a beautiful greenhouse structure, but it must be carefully maintained in order to avoid weathering, rot, and insects.

Cooling and Ventilation for Small Greenhouses Kits

Circulation is a must for a greenhouse in order to replace stale air. Venting of some kind is necessary. Your greenhouse kit should have an easy to open vent on either a sidewall or roof. Most hobby greenhouses in moderate climates can have the door and vent open to create enough circulation.

In hotter climates the air temperature inside the greenhouse can rise 20-30°F/10-15°C hotter than the outside air. If further cooling is needed there are various options including shade cloth, fan and shutter (keeps air in with a couple degrees of outside), and, evaporative coolers (for greenhouses up to 600 sq ft and can cool inside air ~5 degrees cooler than outside air).

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