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will this maybe work for a greenhouse ?

Posted by leava z7OK (My Page) on
Fri, Dec 21, 12 at 14:36

on the back of our studio which is old house next door there is a tiny enclosed porch.cement slab,window,door to outside.for now i just want dedicated space for raising seedlings for spring.i think i could work with it........
besides the heat issue i am wondering if i need ventilation ?? is this a crazy idea ? she who is avoiding buying a greenhouse she may not use ............


Follow-Up Postings:

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RE: will this maybe work for a greenhouse ?

You didn't say what direction your window faces. If it faces north you may need supplemental light. And yes, you will probably need ventilation. I used an east facing glassed porch as my seed starting space for over 20 years. DH built a tall bench with a sand bed and heating cables in the sand. It had a frame over it which I hung fluorescent lights from. Then I covered the frame with plastic on very cold nights. I also heated the whole porch on those nights. But on warm days the area got too hot, so I opened windows and uncovered the bench.


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RE: will this maybe work for a greenhouse ?

the window faces west,no obstruction but small window,this is maybe 6 by 8 or 10 foot space,my patient dh does not want my seedling adventure in house this year.of course it is overflow storage with a ton of junk to clear out........sigh but am willing :)would be safe from critters etc.not to sound dense but how would i do ventilation ? like a vent in wall or ????
my middle name is clueless on this one


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RE: will this maybe work for a greenhouse ?

did you grow plants in the sand or in pots and flats on the warm sand?


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RE: will this maybe work for a greenhouse ?

Leava, I start in pots in flats on the warm sand. I still use the same seedstarting bench, but we moved it to the greenhouse. West facing window will still need extra light, I think to get strong seedlings. I always use lights and put them on a timer to come on at 2am. That gives enough dark time in January and February and the lights also heat the frame a bit on cold nights. Does the window open? What about the door? Is there a storm door that opens like a window? Can you open the door into the house? You can buy screening to cover doors without storm or screen doors. It hangs like a curtain.You would have to monitor it closely, but it should keep out any critters and would be easier to install than having to cut a vent through the wall.


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RE: will this maybe work for a greenhouse ?

I'm hoping the window opens because that would be easiest. I agreee with Dorothy that even with a west-facing window, you might need some sort of supplemental lighting. It could be something as simple as a shop light that holds a couple of fluorescent tube lights. You would need to suspend them by hooks and chains so you can raise them higher up as the plants grow. I keep my lights so close to the seedlings that they almost touch them, and raise the lights as the seedlings grow, always keeping them close to one another. If the lights are too far from the seedlings, the seedlings stretch for the light and get leggy. My light shelf, which is pretty large, has 20 tube lights (4 for each shelf that it lights up) and they heat up the 10' x 12' bedroom so much that I have to close off the heating vent to that room and it still gets hot enough from the lights and the sunlight that comes in from the east-facing and south-facing windows that I have to open up the windows for ventilation in that room on even the colder days. So, on a small porch, just a couple of tube lights likely would generate good enough heat to keep the seedlings from freezing.

That window screening that hangs over a doorway like a curtain is cool. I have those for my greenhouse, so I can leave the plastic-covered greenhouse doors open for ventilation without having every flying insect in the county come and hang out in the greenhouse. I bought mine at Wal-Mart where they were on a hardware-type row near painting supplies and tools. I don't know if they have them on the shelf year-round, but I bought them in early spring.

I'd hang a Min-Max thermometer on that porch with the seed-starting setup from Day 1 and track the outside highs and lows along with the inside highs and lows. That will let you see how well that porch holds in the heat at night so you'll know if you might need to add a little space heater if a really cold spell of weather hits.

Our unheated glassed-in sunroom on the west side of the house has been staying 10-20 degrees warmer than the outside air on cold days and nights this fall and winter. How warm it stays at night depends on how much it heated up during the day and on how much we went in and out that door and let warm air out and cold air in. I could raise seedlings on it, but I don't because the dogs and cats hang out there on cold, windy days and I have found that cats and flats of small seedlings don't mix well.

I don't raise seedlings in the greenhouse because I don't want to heat it, but as soon as I could last year, I moved them out to the greenhouse. Likely that was sometime in February and I left them out there on some freezing nights. The greenhouse stayed just above freezing, but I did have a double layer of floating row cover over the seedlings to help them stay a little warmer by holding in the heat. This works best if you put the row cover on them during the afternoon when the greenhouse has hit its peak heat. If you wait until evening to put the row cover over the flats, some of that heat already has dissipated.

I think what you're wanting to do will work but you will have to monitor the weather and be prepared to put a small space heater on that porch or carry the flats indoors to stay warm if an especially bitter cold spell hits.


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