Building a Greenhouse?

Building a Greenhouse?

My 2008 garden is now brown and barren, and so my thoughts turn to my 2009 garden.

We will probably have to do some construction work in our backyard next spring (e.g., build a new deck), and I thought I might take the opportunity to construct an attached greenhouse. I’m thinking of building out from our exterior basement door, which is located below ground level but leads up to ground level, has good drainage and easy access to water and electrical. I’m not thinking of a huge greenhouse structure, maybe just 10 X 20, but perhaps larger.

A greenhouse would provide an opportunity to get seedlings going early (maybe February?) and then next winter, I’d may be able to get keep root veggies growing until very late in the year (I’m thinking maybe through most of December and maybe even later). In this way, I would be without a garden only a few months every year.

During the summer, I might try to grow some plants that require high humidity, but the main use for the greenhouse would be November - April.

I have not run this idea past The Wife yet, but I thought I’d try a dry-run here.

I was thinking of doing a cold frame type thing next year. Not sure of the design yet. Made of some flimsy wood and a double-ply clear plastic. So that I can take it apart when the weather warms up. Should add a couple of weeks on either side of the season.

Today, since the snow/rain warmed up my garden and perked up my celery to the point that I think it might make it to Thanksgiving dinner, I overturned a large clear plastic bin over it. Wish I'd thought of that last week! I'll see if it works.

Mhays wrote:Today, since the snow/rain warmed up my garden and perked up my celery to the point that I think it might make it to Thanksgiving dinner, I overturned a large clear plastic bin over it. Wish I'd thought of that last week! I'll see if it works.

The celery in my garden was sooo bitter and rough, I found it suitable only for soup. I assume you're using it for stuffing (where I'd think it would also be fine).

I'm still keen on the green house idea, but if that fails to pass The Wife test, I will probably do a hoop house next winter.

Just some random notes, David, that you may well have thought of.

Our home had a small greenhouse in the yard when we purchased it so we've taken it over. It is a blessing in the Stockholm region of Sweden where the cool springs and early autumns make things like tomatoes and basil impossible without its help.

I've had some frustrations with it, though.

Most of them are due to its small size. Greenhouses get hot (even in Sweden - more so in Chicago, I'd imagine) and that extra heat that is so welcome in spring and autumn can be problematic in the summer. That's, of course, handled with proper ventilation. However, many small greenhouses are too small to really get a good amount of venilation. The single-pane window and open door on mine is sometimes too little. Sure, I could always pluck out a pane or two of glass but I never do. So, think about ventilation.

Another difficulty is keeping the greenhouse inhabitants happily watered while we are away. (This could be a Sweden-specific problem as our vacations are normally 5-weeks long and we nearly always travel away from our home...) A kind neighbor usually gets pestered into helping us in this regard.

Finally, keep in mind that the humid and damp environment that a greenhouse creates is tough on wood. The previous owner of our house had put some 2x4's between the greenhouse and its foundation. It finally rotted out completely last year and the repair work required to fix the situation was pretty time consuming.

If I were to build a new greenhouse, I'd have several openable windows for ventilation, a fan or two, perhaps a temperature-controlled motor for opening and closing the windows as well as an automatic watering system built into it. However, the cost of these solutions (at least here in Sweden) are what keep me using the greenhouse we currently have.

Bridgestone wrote:
Most of them are due to its small size. Greenhouses get hot (even in Sweden - more so in Chicago, I'd imagine) and that extra heat that is so welcome in spring and autumn can be problematic in the summer. That's, of course, handled with proper ventilation. However, many small greenhouses are too small to really get a good amount of venilation. The single-pane window and open door on mine is sometimes too little. Sure, I could always pluck out a pane or two of glass but I never do. So, think about ventilation.

That's an excellent point; thanks, Bridgestone. We're in the "pre-design" phase now, and I'll definitely want the place ventilated. I'm thinking a fan and also wing-like upper windows that could be opened during hot days.

Another consideration would be heat-loss during the night...and I'm not sure how to address that. Perhaps some kind of insulated covering that would be dropped down like awnings every evening and rolled up in the morning.

David Hammond wrote:Another consideration would be heat-loss during the night...and I'm not sure how to address that. Perhaps some kind of insulated covering that would be dropped down like awnings every evening and rolled up in the morning.

Many greenhouses take advantage of a south facing brick or block wall. The masonry will absorb the heat during the day and typically have enough heat to last until morning during the mild months. These are typically lean to greenhouses and are installed off of your home or garage.

Here's a link to the lean to greenhouse from a site that sells greenhouse kits and supplies: http://www.greenhousekit.com/julianalean-to.htm

Keep us posted...

tyrus wrote:Many greenhouses take advantage of a south facing brick or block wall. The masonry will absorb the heat during the day and typically have enough heat to last until morning during the mild months. These are typically lean to greenhouses and are installed off of your home or garage.

This is my experience as well.

The original owner of our current home was an "organic tinkerer" and had built a small, maybe 10 X 15' greenhouse off the side of the house. The base, maybe waist high, was brick with the framing and glass panels built on top. He had installed temp-sensitive glass panels in the top that would automatically open when the heat reached a certain degree.

Unfortunately, we are the third owners of this house instead of the second - the "middle" owners had let this little greenhouse fall into a state of disrepair that couldn't be salvaged. But to the point, I still remember how warm that space would remain even into the fall evenings, probably in large part to the brick foundation. The greenhouse was off the north facing side of the house as well. Those top panels, in their final months, would still automatically open to let heat escape even into the evening hours in the fall due to residual heat from the brick.

Best of luck selling it to your better half!

DeathByOrca wrote:Best of luck selling it to your better half!

I got a bid last week. $180K. Perhaps I will wait until the recession recedes a bit...or I'll build it myself (unlikely but not inconceivable).

David Hammond wrote:I got a bid last week. $180K.

Holy Smokes! I'd love to see the specs on that bid. How big is the wet bar?!

DeathByOrca wrote:

David Hammond wrote:I got a bid last week. $180K.

Holy Smokes! I'd love to see the specs on that bid. How big is the wet bar?!

We asked for a lot, expanding the original concept significantly to what would basically be an addition on our house (and more a solarium than a simple greenhouse, per se). I'm sure we could scale back and do it for a lot less.

Given the downturn in the construction market, I was hoping to get a more reasonable price from the contractor, but I think that perhaps because the business is hurting so much, some construction companies are trying to squeeze more revenue out of each project.

Hi,

Is this but one estimate? If yes, then consider getting several more bids. I am a rule of threes (or fives) person who likes to get several quotations, which can vary wildly. If you don't have drawings, each contractor will approach your project differently, which could be educational though for comparisons: apple, grapfruit, orange. If you have rendered drawings, then at least it is a more level playing field to evaluate their estimates.

It is also worth tracking teardowns for the occasional greenhouse that could be disassembled for materials.

A potential wild card variable in your cost of materials may be steel. In the last year has been very expensive, though I have heard it is coming down. You may want to suggest to your contractors, if material costs come down they should alert you.

Regards,

Hi, David and Cathy and others, I'm very happy to see this subject on LTH. Regarding greenhouses/coldframes. I have a coldframe that I bought years ago for maybe $125. It's fairly primitive, but has a vent that automatically opens when it gets hot outside. How does it know!?! Now it's certainly NOT a greenhouse but it does allow for setting out a few tomato plants earlier and growing salad greens a bit later.

My fave gardening offseason item, though, is a seed starting table. I have workbench with regular florescent lights hung overhead on chains so they can be raised and lowered as the plants grow. This is a huge help in our climate and really easy. You don't need grow lights, just regular florescents. For the first season I attached a timer to turn them on and off, but that was too hard, so for the last two years I just left them on 24/7 and that seemed to work fine, tho it did use a bit more electricity I guess.

I'm already burying myself in gardening catalogs this year since the weather has been so depressing. Anybody got any favorite seed/plant sources?

Marilyn

A friend of mine is building one with the double walled lexan sheets and timber frame.

He didn't quite finish it before the winter hit -


He initially had thoughts of moving a glass and steel greenhouse that was going to be torn down, but the contractors quotes just for plans and permits were 10k. So far the major expense was the shipping charge for the lexan - over a grand.

$1000 for shipping? is it the two ply corrugated lexan that looks like this: http://www.lexanegypt.com/lexanegyupt(EN)/images/lexan%20sheets.jpg or were they solid? you could buy a whole greenhouse kit the size of your friends' for that price.. (costco.com sells them, in fact, which includes shipping costs).

...this whole post came about 2 months too late for someone wanting freebies. we had a 5x8 greenhouse on our roof that we had purchased from one of those kits... the metal frame just wasn't sturdy enough for chicago winds (or rather, for chicago winds atop a 40' building...?). it was a POS as far as durability and every time it got really windy it was a mad rush to repair and anchor it better... eventually it blew to pieces when we had those 90mph winds last winter.... i threw the metal frame out, but kept the plastic lexan sheets thinking i'd rebuild it stronger with wood.... never happened.. and the day we were moving out after selling the place i left all the plastic sheets in the alley. i picture in my head them blowing away like a tornado had hit the alley, but maybe some keen eye caught them in time. there wasn't enough time to really dig around for a good taker though :/

...that said a few tidbits...

i made it extremely sturdy by siliconing all of the joints with silicone caulk... (the real problem them is that made the thing into a giant sail, so when it finally broke away it didn't fall apart, but rather ripped the bolts out of the concrete wall that were anchoring it...).

the air temperature is a real issue though. the same things that insulate it when you need will make it get too hot when you don't need. in the summer we had to keep the door wide open or it would be too hot. it really served no useful purpose in the summer, except we could've had bananas and other tropical stuff that wouldn't otherwise grow. also, some plants prefer a really warm day then a cooler night, and it's harder to control that in a greenhouse... my next point of modification was going to be replacing one of the panels with a screen and mounting a fan for ventilation... then somehow being able to re-insulate that area in the winter would be essential.

in the winter, it actually did a surprisingly nice job keeping its temperature. we bought a very small outdoor greenhouse heater (electric powered, looks basically like just about any other space heater really... probably any "garage" heater would be an equivalent..) and had it plugged into a thermostat switch that would turn it on when it dropped below a programmed level. we were surprised to find that we had a hard time staying in the greenhouse long enough to see if/when the heater came on. we know it did at some point, but it wasn't on enough to even notice it really. and more importantly we never noticed an increase/decrease on the electric bill... had we kept it around a bit longer i would've probably hooked it up to something to measure exactly how often it came on. (we did have a wireless outdoor thermometer gauge placed inside, but the temp readout of that showed the temps were relatively constant).

i did a lot of research on "passively" heating the greenhouse... the problem is i didn't really get too involved in caring about that until it was too cold to really be outside working on it. so as a temporary passive measure i filled old wine bottles with water and left them sitting in various spots within the greenhouse... (theory being that water holds temps longer...). i have no idea how well this helped and would have liked to have done more real measuring of it in a temperature where it wasn't so extreme, but i don't think it hurt either ... (if you do this and then ever let the greenhouse get outside air temps, remove the bottles or they'll freeze and shatter)

but if you google around, there are entire greenhouse plans for passively heated greenhouses... some people have built home-made water heaters almost that circulate to heat... (think a grid of wine or beer bottles attached to a board, interconnected by tubes, placed on the inside roof, or a back wall, etc). i've seen some that use hay bails as a wall, which somehow helps.

$1000 for shipping? is it the two ply corrugated lexan that looks like this:

I definitely misquoted him. That was the total, and included some of those big plastic barrels - for passive heat retention. This lexan is the heavy duty stuff, and this thing isn't going anywhere - you could stand on this stuff with confidence.

I think the next issue is electricity for lights and the small water heater. The power in the garage it's next to probably isn't enough. Getting a professional of course is the only way to run a new line, and that brings up permits and whatever crazy zoning a little house probably bans.