A greenhouse is a structure with a plastic or glass covering. They are designed to protect out of season plants in a more controlled environment. Like overwinter plants.

A cold frame is a transparent roof enclosure built low to the ground, essentially a smaller greenhouse. This is called a cold frame or mini greenhouse

Points to consider when deciding which covering to use are:

• Cost
• Durability
• Maintenance
• Retention of heat
• Transmission level of active radiation (plants respond to different amounts of sun, shade vs full sun)

Types of materials that are available are:

• Glass – traditionally used for greenhouses-has a high level of difficulty for installation but low maintenance costs.
• Plastic films – most commonly used in Australia are cost-effective and easy to install (there are different films with different advantages).
• UV resistant greenhouse plastic sheeting (polycarbonate), acrylic (polymethyl methacrylate) and fibreglass (not as popular in Australia).

When designing your DIY cold frame, polycarbonate greenhouse plan or a DIY greenhouse of any other design, see what other greenhouse gardeners have built and what works. 

Designing and building a cold frame, small greenhouse or even a large greenhouse from connectors and PVC pipe is an obvious choice because they are:

Easy to assemble-

Cut your pipe to the required length (this means you can have the size of the greenhouse that you require), slide it in the connectors to make a frame, and use screws or snap tabs to attach your plastic sheets or glass to the structure and snap clamps to secure the plastic film. Unlike metal or wood frame, you don't have to learn how to weld or hit your thumbs with a hammer. A DIY greenhouse PVC frame is also lightweight while still being strong enough for building structures.

Durable-

The connectors and pipe from Klever Cages are UV treated, so they will last and will not crack. The connectors are purpose-built for building structures (unlike plumbing fittings designed to be placed in the ground with the sand as support around them). The connectors are high quality so that they will last many seasons.

Customisable – 

You can design and build the structure to any size or shape you want! No matter if you want a walk-in greenhouse, a small one or even to put one over your raised beds. If your requirements change later, you can modify it by pulling the pipe out of the connectors and redesigning it with new pieces. The plastic film can also be changed easily to a shade cloth or bird exclusion netting by taking off the snap clamps and replacing the material with a different one.

Corrosion proof – 

PVC will not rust or rot like metal or a wooden frame. The material is non-porous, so it will not absorb moisture or odours.

Versatile - 

You can disassemble your project and pack it away or take it with you when you move - great for rental properties!

Cost effective – 

As you design and build it yourself, you control how much you spend. You do not need to hire anyone to make it, nor do you need to invest in expensive tools to put it together. Basic tools and accessories like screws, nails, and glue can be used to reinforce the structure if you choose to.