Greenhouse: Planning

‘Who loves a garden loves a greenhouse too.
Unconscious of a less propitious clime,
There blooms exotic beauty, warm and snug,
While the winds whistle and the snows descend.
William Cooper, The Garden

Got a Greenhouse in this year. Before I start I should point out that a lot of people on projects like this are excited when they finish building but readers don’t know how it’s working for them a year later. For this reason, a full evaluation would be premature. This series is just about how the thing came together, and why I bought what I did. Next year I’ll do an update and we’ll evaluate it. 

Here are some of the planning questions:

Where will the greenhouse live?
Why do I want it?
Is it worth it?
Should I ask the city about permits?
How much food can I grow in it?
What brand of greenhouse?
How big should it be?
How much will it cost?
What other costs are will there be?
How long will it take to put together?
What tools do I need?
What can I get done in advance?

Where will the greenhouse live? Factors being sunlight, prevailing wind direction and load, access to water, access from home, need for a level base, nearby trees/branches that might shade it out or land on it in a windstorm. It can rain and blow for weeks at a time here, especially in fall, and we get dramatic changes in seasonal light–18 hours of sun on summer solstice means 18 hours of dark on winter solstice. At spring equinox we’re gaining 5 minutes a day, fall equinox we’re losing the same. So, it’s good to watch how the light plays on your yard through the seasons as you plan.  One gardener told me I should cut down all my big trees and put in a 40 foot greenhouse. I like the trees for privacy and birds, so they stayed. The greenhouse gets morning sun in one end, afternoon sun in the other. It’s a balancing act.
People are more likely to spend time in the garden or greenhouse if it’s close to home. That said, you don’t want it so close beside another building, wood pile, dead truck, etc. that snow can compact between the two and stress the greenhouse. Worth researching (discretely) if there are any city ordinance issues about putting it where you want it? (See note about city bureaucracy below)

Why do I want it?  A:  More control over what gets into the garden; keeps out birds, deer, slugs and all that eat seeds or plants. Keeps out heavy rains can also wash out seeds and shorten the growing season. Expand the growing season by a few weeks either end. A few weeks makes a big difference in the harvest. Gardening tools and pots can spend the winter in there.
And not least, it’s great head space. Even on the nastiest day, when it’s been raining for weeks on end, it’s great to go out to the greenhouse with your morning coffee, even before there are any plants in it. Just to sit and listen to the wind and think, “This is great.”

Is it worth it?  A: Yup. Any three dimensional activity that keeps us away from the flat-screen wasteland of the internet is worth it.  Plus you can spend time there with the kids and grand kids. Give them seeds, some pots, dirt, and they’ll see that their food isn’t born in little plastic bags at the supermarket.

How big should it be? A: One of the most common comments from people buying greenhouses is, ‘Buy the next size up from the one you think you’ll want’. Some, like the Planta Sungrow are expandable after you build them. Originally I planned to get the 13 foot long Urban but went with the next size up at 20 feet.

Should I ask the city for permission? A: Up to you but my experience says don’t if you can avoid it. Except for those with a lot of money, “Can’t” is to city government what “OM” is to Buddhists. A mantra. “You can’t.” “I can’t.” “We can’t.”  Om mani padme can’t.  Given that the world food supply is more tenuous every year, and that there’s no road into Juneau, and that nearly all our food comes in by barge, and that our town was better prepared for a food crisis 100 years ago than it is now you’d think city officials would do all they can to support growing food locally. You’d be wrong.
Look at the photo above. In our town you don’t need a building permit for sheds and outbuildings under 200 square feet. My plan was the 10 x 20 greenhouse extending to the edge of that raised bed you see on the outside.  The end is several feet inside our property line. Trying to be a good citizen, I made the mistake of asking a city official where the set back was. Typically the rule is an outbuilding wall has to be at least 5 feet from the property line, a roof at least 3 feet. So I was golden, right? Wrong. Got a message from a town bureaucrat who said the set back on that side of the house is 17 feet. Which is crazy. She provided no reason for it. I asked a few contractor friends who’d never heard of such a thing. They all wanted to know, “How’d they find out?” When I said I’d asked, they looked me like I had two heads and said, “You did what?” I could have applied for a variance. Maybe would have got it, maybe not.
Not wanting to go all Marvin Heemeyer on this, I ended up splitting the difference. Size is now the size of the Sungrow Urban.

How much food can I grow in it? A: Depends on gardening experience, what you’re growing, weather (unless you’ve got light and heat in the greenhouse). We have people in town who grow enough food to give plenty away to neighbors but, for most people a garden or backyard greenhouse typically augments home food supply rather that grows your whole food supply.

What brand of greenhouse? A: Because of where we live, my top criteria was something that can take wind and a snow load. After spending years looking at various greenhouses I settled on a Planta Sungrow.  It’s sturdy; has an arch design that sheds snow, is rated for 98 pounds/square foot, rated for winds to 65 mph.  Other greenhouses in the price range (some almost twice as expensive) were rated for the same loads or less, and didn’t look like they’d hold up. With global warming we get wet snow loads heavier than that, and winds higher than that, so we’ll see how it goes.

Planta workers weigh in on how sturdy these are.

How much will it cost? A: Click on the link at the end for the current price for an Urban. As of Fall, 2023, they’re around $3,000. Next size up is $3,800  Planta runs specials regularly, especially during winter that will save you between $150 and $250 depending on size. You can order it and have them send it in spring. If you’re planning to extend, there are kits to do that, but it’s cheaper to order the larger model at the get-go. There are lots of extras like heaters, roof vents that automatically open and close, running electricity and piping, etc. that add cost if you want them.

What other costs are will there be? A: In my case extras were: shipping–which is expensive here (about $400), compacting gravel for leveling out a base ($200), tight construction grade yellow cedar foundation (about $1,500) (worth it, didn’t want pressure treated wood near my vegetables), wood and fastenings for raised beds ($300), pots, the usual garden stuff which I mostly had: soil, seed, plants, fertilizer… I also bought heavier, longer self-tapping screws for the  bands that hold the metal straps to the base. Had most of the tools but bought a metric tape measure and a couple other tools I’ll go into in ‘Things that helped’. Also bought extra greenhouse tape ($120) got a metalized tape for sealing the top panels, and a special tape that lets water from condensation weep out the bottom). * too expensive, it’s all relative. People pay more for big TV sets, or a cruise to Alaska. Anyway, you don’t need to (shouldn’t) go into debt for a greenhouse. They do layaway plans like our parents used back in the day.

How long will it take to put together? A: Everybody’s different. Some with a work party do it start to finish in a weekend. Mine spent the winter partly assembled in the shed. If you get to a point where you’re all amped up and agitated because you want to get it done by winter and it’s about to snow, relax. Let it go until spring.

What tools do I need?
See the post on ‘Things that helped.’
What can I get done in advance? Put in the gravel pad. Build the base. Assemble the arches. It’s fun to do a couple of those on winter nights.  You can stack them until you’re ready to put the whole thing together. That way you’re ready to hit the ground running when the days get longer.

*As always, I don’t take any money, free stuff, or perks of any kind from companies I mention.