At this time of year, when we long to be out in our gardens, many may be thinking of adding a greenhouse. They are great for extending your growing season, starting seeds, and providing stability and flexibility for more tender plants. While greenhouses can be a beautiful addition to your garden, there are a few things that should be thought about before diving in. We hope these will help you decide if a greenhouse is right for you.
Types of Greenhouses
The type of greenhouse you need is going to depend on your location and climate. They range from cold houses to hot houses with options for in between. On one end of the spectrum, cold houses help protect plants and extend your growing season by allowing you to start crops earlier in the spring and grow them longer in the fall, but the temperature in the greenhouse can still go below freezing due to no supplemental heat source. Hot houses on the other hand have supplemental heat sources and are mostly used for tropical plants since the temperature inside can be controlled. In the PNW, you’ll know that we have a lot of gray days in winter, so the sun is sometimes not the best to rely on for a sole heat source.
Location on Property
While having a flat spot to put your greenhouse is very important, you’ll also want to consider large shade trees that could potentially block sunlight along with water and electrical needs. In general, the best spot is going to be a south or southeast facing location that’s sunny and gets sun in fall through winter. If you are placing the greenhouse farther away from your house, you may need to run water and install a hosebib at the greenhouse location. You may also need to run electrical and install outlets in the greenhouse if you are adding a heat source or any other controls.
This category includes things like heating equipment, ventilation, and watering systems. If you choose to not have any automatic environmental controls, you’ll need to think about how you’re going to heat the greenhouse (if needed), how it’ll be ventilated, and when and how you’re going to water. The conditions inside a greenhouse need to be monitored regularly so coming up with a schedule to water and care for the plants inside is important and depending on size, can take up a substantial amount of time.
If you do a quick google search for greenhouses you’ll see that there are an unlimited amount of choices for greenhouses out there. This is because greenhouses can be made from several different types of materials (wood, metal, plastic, etc) and covered in several more different materials (glass, plastic, polycarbonate, etc). Depending on the options you choose, you could be landing yourself with more maintenance than anticipated. The frame itself is important to consider. Both wood and metal frames will be heavy making them a good fit for permanent locations. If you opt for a wood frame, make sure to look for high quality wood like cedar that has a natural resistance to things like moisture and insect damage. Coverings like double or triple layered polycarbonate or glass glazing are more expensive up front but will last the longest while providing diffused light in. Unless you are doing a non-permanent or moveable greenhouse setup with a collapsible frame, you may want stay away from polyethylene film as it is thin and needs to be replaced regularly.
Whether you decide to have a supplemental heat source or automatic environmental controls or not, it’s imperative that you monitor your greenhouse frame and coverings along with any other additional systems routinely to keep up on maintenance before anything gets out of hand.
While a greenhouse is a closed environment for the most part, pests still manage to get in (usually from new plants being brought in). To begin with, if you have an area where you can keep new plants for a week or so before entering the greenhouse, you should be able to keep most insects out. Monitoring new plants for a week allows you to watch for any potential insects and deal with them if need be before introducing them to your collection. Another area where pests can be introduced is any plants growing close to your greenhouse. Keeping the area around your greenhouse well maintained is just as important as the inside.
If you were on the fence about a greenhouse, we hope this post has made it a bit easier to make your final decision. While greenhouses are an investment in both time and money, they can be so useful in the garden and not to mention pretty to look at when the snow is falling.