Greenhouse Thoughts Part II
ringing a greenhouse into your life is a commitment for sure. One caveat, though, if you don’t want to garden a lot or for a good portion of the year, think twice. A greenhouse, even a cool one needs attention. They cool down fast at sundown and heat up even faster when there is a break in the clouds.
Ours has served as a classroom, my daughter learned to read by deciphering seed packets. She also learned the value of garden work too, there are many chores in a greenhouse that can be handled by small children. Besides chores, valuable life lessons can be taught. Observing your food from seed to table comes to mind.
While we choose to not “grow” vegetables in the winter that require protection, winter harvesting is a compelling reason to have a greenhouse. Any of Eliot Coleman’s writings can lead you in that endeavor.
However, our chickens enjoy their small greenhouse during the winter.
And they get their start in a small greenhouse too.
Styles vary, commonly you see semi-gable like our large greenhouse or quonset and semi-quonset like our smaller brooder greenhouses. Both have pros and cons. We have found the semi-quonset to be stronger in snow storms than the semi-gable. However, you can order or make trusses to strengthen the semi-gable structure. A good place to peruse styles is the FarmTek catalog, you can familiarize yourself with the terminology and get an idea of what is available, but I would recommend buying from a local company if you can.
Basically you determine the width you want, and you can customize the length by buying more bows. One of the determining factors in this part of the design is the plastic width and length. Our 30 x 72′ greenhouse uses one roll of 48′ x 100′ roll of Tufflite IV, this covers the entire top and sides and leaves enough for endwalls.
Site consideration is very important for several reasons. Questions to ask yourself when you’re picking your potential greenhouse site:
♥ Are there any trees that will cast shade on your greenhouse? Winter time is a good time for this exercise when the sun is the lowest in the sky.
♥ Is there easy access with a vehicle, so you can deliver supplies, and remove your harvest easily?
♥ What do you want to grow, tall crops, short crops? And when, summer, winter or both?
♥ Do you want to use part of your hoophouse for tool/equipment storage or only for growing?
♥ Visit growers in your immediate area and pick their brains, do they like how their greenhouses function, what would they do differently? What are their biggest weather concerns…heat, wind, snow, flooding, hail?
♥ Orientation? Winter crops will do better with an east/west orientation since that will give you a little more heat in the winter, north/south will give you more light to all your crops during the growing season. Even with an east/west orientation in cold winter areas you will still need additional heat and/or additional covers for plant protection.
Our greenhouses are oriented north and south for maximum light to all the crops during the growing season. Our gardens are the laid out the same. This is where you get all sorts of opinions and reasons for east/west orienting versus north/south. Remember this is a blog post about our farm and our experiences which may be different from what you know or think or have seen in practice. It’s now recommended by the USDUH that any hoophouse constructed north of the 40° parallel be constructed on an east/west axis. I will disagree (we are at the 45 parallel) for several reasons. You can gain a little more light through the sidewall than through the roof if you are oriented east/west, but that is more of a winter consideration and fails to be even noticeable in the summer. I would say if you’re wanting to grow in winter and need to retain heat, east/west axis is more important, however be prepared for that greenhouse to be too hot during the summer without adequate ventilation. Length plays a part on that too, any hoophouse longer than 48 feet without much sidewall or end wall ventilation may get too hot for most crops, especially if it is oriented east/west. Roll-up sides and adequate vents can help with that. I know growers with houses oriented both ways, and the east/west folks are mostly concerned with winter growing for their hoophouses, but they orient all their summer outside vegetable rows north/south. A neighbor who has an east/west hoophouse for personal use is now wishing she had built hers the other way. She grows tomatoes and peppers mostly in her hoophouse and now realizes that she is committed to always having her tomatoes on the back side, since she discovered the second year in her rotation that if she planted her tomatoes on the south side of her greenhouse, they shaded all the other plants by August and severely diminished her harvest on all plants shaded by the tomatoes.
For us, the north/south axis works great, even though we may be sacrificing a little winter heat. The south end wall provides enough shade I can still start plants in the greenhouse during the summer as the seeding bench on the north wall gets too hot by June. Likewise, the hot north end in summer becomes the warm north end in winter and is perfect for my over-wintering greens. Just like any garden, seek out the different micro-climates.
Other things I consider important in our greenhouse. They may or may not apply in your situation.
♣ No formed beds – this means it’s pretty easy to add amendments and work the soil. Even if you don’t have a tractor, you don’t need to commit yourself to a lifetime of amending your soil with a wheelbarrow. You can hire someone to till for you and haul in your compost at the beginning of the season. No fixed beds keeps your options open.
♣ Wide sliding doors for easy access. Hinged doors are heavy and are always in the way and hard to open, soil and debris build up over time making a swinging door hard to use. When designing your doors, think of how you are going to use it, at least wheelbarrow width plus for a minimum.
♣ High side-walls so I can work the soil with equipment. The taller roof also helps with ventilation. Lower styles are nice too, but they do get wicked hot for plants, and the workers. We used our greenhouses for winter laying hen housing, and cleaning out the deep bedding was much easier with taller side-walls.
♣ Roll-up sides for cross ventilation. Not necessary, but it’s really a nice feature.
To conclude, these items were/are important to us when deciding the what, where, and how of siting our greenhouses. You may have more factors to take into consideration for your own project, but hopefully this is good food for thought.