If you don’t have a greenhouse, maybe a mini seedling greenhouse made out of UV plastic and PVC is up your alley?
We built this mini seedling greenhouse several years ago, prior to building (and more importantly, insulating) our actual greenhouse. Its sole purpose was to allow us to get some of our seedlings outdoors as early in the season as possible. As we were expanding our gardens, it became essential to have a safe, outdoor place to have our plants while frost was still a threat. You’ll find our full build guide down in the comments.
This small greenhouse was quite easy to design and build. It allowed us to weather many frosts and even decent snowfalls. It uses fairly common PVC fittings and 1-1/4″ PVC pipe, which is reasonably rigid. The UV plastic is secured to the PVC frame using PVC clamps. Overall, this unit was relatively inexpensive to build. You could take the design many different directions, should you so choose.
Many, many moons ago, we used inexpensive plastic greenhouses (e.g. Gardman brand) for this same purpose. We became annoyed at the very low quality of the plastic covers, which forced us to replace them annually and sometimes even multiple times per season. We found our DIY version much higher quality and up to the task of Alaskan winters. Since there’s no stupid zippers or other complexity, a simple roll of clear UV rated greenhouse tape is all you need to keep its longevity.
These kinds of small greenhouses can even be heated and ventilated, if desired. It’s important to know that any greenhouse can produce plant killing temperatures, even in cold climates, so ventilation is a key component to greenhouse design. You can do this either via manual intervention (i.e. lifting it up) or full blown temperature control via fans and heaters. We like using Inkbird temperature controllers, but its important to pay attention to power draw as most models can only handle 10 amps. This becomes really important when heating as many 1500 watt space heaters will exceed this value. (We had great luck with a single 750 watt heater!) So, be safe!
The beauty of building out of PVC is you can store it outdoors, through our harsh winters, without any concerns whatsoever. The last thing most of us need is more stuff that has to be inside! It might be wise to remove the plastic each year. But, we do think these things can take a bit of snow load, assuming you’re interested in experimenting and could stomach replacing the plastic outright if you’re wrong!
So, if you’re looking for an interim step between a full blown greenhouse and throwing your plants into the cold void, this was a solution that worked well for us!
