Questions about Greenhouses

Questions about Greenhouses (post #16061)

Londonhouse on Mon, 01/04/2010 - 19:31

General Gardening

I am interested in setting up a greenhouse, but not sure how to go about it.
How much daily exposure do you need to sun?
How do you heat it (and how expensive)? (It would be free-standing and not attached to any building.)
What is the best size (I would like to start seeds and maybe overwinter a few plants)?
What type of foundation does it need?
Do they all have some type of venting?
Is there a high risk of glass breakage during winter due to snow and ice?
Are they English Setter-proof :) (Our dog is 9 months old and his name is Spencer, but we nicknamed him Dennis the Menace, I think he must be somehow related to Marley.)
Anything else I should know?

I like the Hartley style greenhouses, but don't really know that much about them.

I went to a home and garden show last year and saw some, but the salesperson only explained how they were constructed.

Would like to know your ideas, experiences and knowledge on the subject. Thanks!

It is suggested that a basic

by Astrid Churchill in reply to Londonhouse [original] on Tue, 01/05/2010 - 13:16

It is suggested that a basic greenhouse be aligned with the course of the sun across the sky for the most light to be captured, basically east to west.
If you have need for shade you can try a more complicated placement, possibly shade cloth.
Measuring carefully before buying and constructing is very important. Avoid placing a greenhouse under trees because of the element of tree limb breakage. The main direction of air movement is also something to consider for preventing mold etc.

A sure light in the heavens.

Thanks - that is helpful for

by Londonhouse in reply to Astrid Churchill [original] on Tue, 01/05/2010 - 15:54

Thanks - that is helpful for placement. On the east side near the open field there are no trees. Wind direction is usually west to east. I live on a very big hill (can see mountains in all directions) so very windy. This is also the high side of the property so drainage is good.

I just built one in NC and

by Karen in reply to Londonhouse [original] on Thu, 01/07/2010 - 16:43

I just built one in NC and spent over a year before that reading and planning. My needs are somewhat different from yours since I'm so much farther south, but a good starting place is to decide as specifically as possible what you want to do in the greenhouse. In particular, what plants do you want to overwinter -- that will give you an idea of what internal climate you'll need to maintain in the winter, which will guide your choices with respect to covering, frame, heating, etc. Do you have any intention to use it in the summer? Up in NH you might be OK with roof vents, but down here I've got evaporative cooling. I found a lot of very useful information from various Cooperative Extension Services throughout the southeast when I was planning. Georgia and FL had esp good sites for me. If I were you I'd check out your NH CES website, but also adjacent states, to see what they recommend. Some of the info targeted at commercial operations is more useful than you might think. For example, here's a discussion from UMass of how roof and side vents work together to cool in hot weather. http://www.umass.edu/umext/floriculture/fact_sheets/greenhouse_managemen... Finally, I called and spoke with several greenhouse companies before I bought my 'kit'. I ended up with a company in South Carolina that was most in touch with my climatic challenges.

North Carolina - zone 7

Depending on what you want to

by TomHigby in reply to Londonhouse [original] on Mon, 02/08/2010 - 17:56

Depending on what you want to grow, many of your questions may have several answers.

We built onto our house an 11' x14' Lord and Burnham curved eave structure about 40 years ago. It had a small gas heater, roof-vents (some thermostatically controlled), a 3'masonry wall.

We thought that we would grow tomatoes in the Winter--impossible without huge cost in heat. (Michigan) We shifted to growing cacti and succulants, with good success, much more tolerant.

Controlling sun-light has been a big poblem,now solved by aluminum roll-up blinds, and a large shade tree that wasn't there when we built the green-house.

We are still growing some cacti, but now more into orchids,with many now in bloom. We have a larger heater, table and chairs, and take most of our meals among the flowers. With the shade-tree, we no longer use the roof-vents, and are no longer bothered by over-heating except in Spring before the leaves are out.

As you can see, controlling Winter cold, Summer heat, and intensity of sun took us a while. In spite of all that we would hate to be without our green-house.

One must remember that green-house plants are like babies, require mothering, and do not do well left alone. In earlier times we took vacations, always experiencing severe plant loss, even with supposedly capable baby-sitters.

Good luck
Tom

Thank you for your helpful,

by Londonhouse in reply to TomHigby [original] on Sun, 02/14/2010 - 18:02

Thank you for your helpful, informative comments. There is a lot more to this than I realized. I will need to re-think the greenhouse.

I live on a very windy hill (great mountain views though!).
Positioning the greenhouse as a freestanding structure in the back of the property (the only flat area) would be difficult due to trees.

If I attach one to the house, the only side that can accommodate it would be the side facing North - northwest, which is cool in the morning and hot in the afternoon with only about 3-4 hours of direct sunshine during the peak of summer and protected from high winds.

The cost of heating sounds pretty scary - if you pay that much down south, it sounds like it would be astronomical up here, which is probably why I don't see any greenhouses in use during winter except for a few commerical ones!

I would like to start bedding plants to mix in with hardy perennials (i.e., "Profusion" zinnias) and overwinter some tender plants, such as Rex Begonia "Red Tango" and "Magma," mandevillas and ivies.

I have a few houseplants, but my passion is outdoor gardening.

Researching further with the UNH Cooperative Extension Service is a good idea. However, I am open to other ideas as well! Anyone else garden up north?? (Zone 4)

It takes a lot more heat to

by Karen in reply to Londonhouse [original] on Tue, 02/16/2010 - 11:20

It takes a lot more heat to grow and fruit tomatoes through the winter than to start bedding plants early or overwinter tender perennials, so don't let that scare you off. Your biggest winter problem in that location sounds like it might be light, but you could start seedlings under supplemental lights if that's the case. If you just want to overwinter the begonias and mandevilla and don't need them to do any growing, you can do that in fairly cool, lower light conditions. Before I finally built my greenhouse I routinely wintered both of those in the garage, where the minimum temps were between 35-40 degrees and the light came from just a couple of windows. They weren't what I'd call happy with the situation, but they lived and grew again just fine come spring.

Here is a links to another gardening forum with photos of a New Hampshire greenhouse. I don't know what he grows in there or what his heating bills are, but if you post in that forum he might be able to help you.

http://forums2.gardenweb.com/forums/load/strucs/msg0110314831144.html

North Carolina - zone 7

Greenhouse

by StorageShedSmart in reply to Londonhouse [original] on Fri, 04/02/2010 - 18:39

I recommend that you choose a greenhouse that will be easy to assemble and is made of weather-resistant materials. There is one that I know that will protect your plants even through the winter. This is the Poly-Tex Snap and Grow Greenhouse. It can be built on a wooden or concrete foundation. It is made of polycarbonate panels that are transparent but are not breakable like glass.

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