These types of inexpensive "portable" greenhouses have been around for a long time now and are becoming very popular in the USA. The quality of the materials used in these types of products is improving each year and the prices are remaining low. With winter approaching in Australia one of these easy to assemble and reasonably priced plastic covered aluminium framed greenhouses can come in handy!
I live in a subtropical climate and although it's considered warm our winters can still get cool enough to prohibit the growth of certain plants such as tomatoes. However, with a simple greenhouse, the plants are protected and kept warm enough to flourish – no heating required or special fans etc just the plastic enclosure increases temperatures enough to do the job.
For cold climates, this type of greenhouse would probably work better with some type of heater like heated seed raising mats or a similar product. There was a guy on our forum www.selfsufficientculture.com who used a standard electric blanket in the base of his mini-greenhouse to warm up the seedling trays… ingenious maybe but possibly dangerous also.
The two plastic cheap greenhouses I have are both smaller than the Certa Greenhouse 3×2 and are many years old now. The larger one came with a plastic frame and the smaller one was alloy. The clear plastic cover that came with mine eventually deteriorated and whilst you can buy replacement plastic covers I ended up covering mine with shade cloth. Nevertheless, I'm still getting good use out of my mini greenhouses to raise seedlings etc.
I suspect the Certa Greenhouse would have a better quality UV resistant cover than my old greenhouses did and from the reviews online it seems like most people are very happy with their purchase.
Some of the reviews are what I expected actually with one person saying, "the plastic cover is a little thin but the frame is good" and another stating "looked and went together well – can't wait to grow a storm!"
Speaking of a storm, one reviewer commented how he thought the anchor points on the base of the greenhouse could have been better and I can relate to this because from my experience these types of plastic covered and alloy framed greenhouses don't have a very good mechanism to pin it down against high winds. That's why I used my own ways to anchor the greenhouse down such as posts driven into the corners and the greenhouse secured to them and/or bricks etc used as weights on shelving to keep it heavily pinned down. Naturally, you could secure the base of the frame to paving, concrete, or another structure if it's located in the right place.
For those in the USA there's an awesome selection of cheap easy to assemble greenhouses similar to the Certa here on Amazon.
In the UK, there's a similar selection of well-priced greenhouses here on Amazon UK.
If you're looking to buy to a greenhouse on eBay there are plenty to choose from also:
Modern cheap mini greenhouses are a handy piece of kit and I think they are terrific value and a great investment for the backyard gardener. At the end of the day, I don't understand why you would bother building your own small hoop house when you can buy one of these for less money and easier to make – probably have it assembled within an hour. And, I do think they look good too.