Is a Greenhouse for You?

Greenhouses provide shelter from wind, extreme cold, hail, and most large pests.

Do you have a short season? If so, a greenhouse of any size will provide the the extra days needed to grow a wider variety of plants. Factors to consider when choosing a greenhouse:

Cost

Plastic and aluminum are more affordable while steel and glass cost more. A budget is a good starting point when deciding what type of greenhouse your need.

Your budget will breakdown to include costs such as building permits, excavation, footings and foundations, materials (frame, glazing, doors, fans, electricity, and plumbing), labor for assembly, imported soil/amendments, and finally, seeds and plants. The longer you plan on keeping and operating your greenhouse, the greater the initial cost pays for itself. If you are unsure if a greenhouse is for you, you can start with a more cost effective high tunnel, cold frames, or small hobby greenhouse.

Size

Is this for hobby, commercial, or somewhere in between? The larger the greenhouse, the greater the thermal mass. Larger greenhouses take longer to heat up and cool down. Because a greenhouse can fluctuate more than 60 degrees in one day, the size is important to consider! A cool but sunny January morning may start at 20ºF and end up at 80ºF within hours. The ability to capture this thermal energy lowers heating costs and stress on your plants. By harnessing heat, the greenhouse greatly improves growing potential. Make sure to leave plenty of space for plants, a work table, and walking paths.

Glazing Material

Glazing material is what covers the frame of the greenhouse and provides protection between the outside world and your plants. While glass can be a very attractive option, errant rocks from a mower, large hail, or falling limbs will keep you replacing panes and pose a danger for you and your plants. Single layer plastic or glass will not provide much protection from cold, but it will for wind, rain, and most animals. An 8mm, double wall polycarbonate is a great choice for northern greenhouses as it is capable of withstanding heavy snow loads, high winds, flying debris, and provides good insulation while maintaining light transmission. Adding a solid insulated wall on the north side of the greenhouse also aids in reducing heat loss.

Framing Material

Galvanized steel is the strongest and most durable framing material, especially necessary in snow and wind prone areas. Pressure treated wood is a viable alternative depending on the size of your structure. For snow areas, framing should be spaced at 4ft intervals to help support heavy snow accumulation and guard against damage from wind.

Planting Medium

Three main options for planting mediums include:

• Direct planting in the soil,

• Raised boxes or pots

• Hydroponics (planting in water).

The last two options are better suited for a standard fixed foundation greenhouse. Hydroponics greatly decrease the need for water (up to 90%), and reduce pests, growing space, weeding, and add greater control over fertilizing. While the benefits of hydroponics are numerous, there are greater infrastructure and operating costs. For those gardeners who love the smell of warm earth, the discovery of earthworms, frogs, and an occasional praying mantid, or they if want perennials in their greenhouse, hydroponics might not be the best option.

Enjoyment

Is your objective purely production, or is this a sanctuary for your plants AND you? There is nothing quite like basking in a tank top and shorts in an 80ºF greenhouse on a sunny day in February when it is below freezing and there is snow on the ground.

Options in Summary

High Tunnel

Pros: less expensive, flexible, no need for electricity and plumbing, extends growing season by protecting plants in the spring and fall.

Cons: plastic glazing usually is replaced after 4 years or less, may not handle high winds and heavy snow, harder to provide accessories such as electric fans or automatic watering systems, plastic sheeting must be raised and lowered manually according to weather conditions, and there is less protection against pests.

Fixed Foundation Greenhouse

Pros: Great for year-round use with durable glazing, capable of withstanding wind and snow, greater resistance to pest invaders, capable of adding automated vent fans and watering system, and a greater range of plants can be grown.

Cons: more expensive initially, additional electrical costs for heating and ventilation.

For in depth information glass vs. polycarbonate see here. For information about heat loss and R-Values see here .

Young turkeys enjoy the shelter of the greenhouse while eating bugs.