First time using my little greenhouse

platys · March 1, 2011

This is our first spring in our new house. The previous owners had built a little "mini greenhouse" off the garage - mainly, its a small room with mostly glass on 3 sides. It has a whole seed starting setup, including working shop lights and shelves. It was one of the selling features of the house to me.

The previous owners probably used the gas heater that is built into the room. However, we've been advised to not touch the thing, given that it hasn't been inspected, and there's no reason to think it would pass inspection.

So, I'm realizing that I'm going to have a serious cold problem. In May in my area of IL, the average night time temps will still be below 40, but not by much. I read that having the seedlings be cold can be good, but is 35-38 too cold? I'm assuming the shop lights will put out some heat. If I add heating pads, would that help?

I know I'll have to start the seeds inside the house, no matter what. I have four cats, so finding a spot will be a challenge.

laspasturas · March 1, 2011

Lots of people who grow in hoop houses also use row cover inside for an added barrier from the cold. Something like that might work in your set up.
I'm jealous, by the way! It would have definitely been a selling feature for me, too.

puttgirl · March 1, 2011

Lucky you! I'd love it, too. If the area's not too large, I'd just go with a small ceramic heater. It doesn't have to be too warm, and you can get the heaters pretty cheap these days.

platys · March 2, 2011

I had someone tell me I could put cans of water in there, and it would act like a solar heater at night. I think I'll start monitoring the daytime temperatures, and see what happens. I doubt that right now, it retains any day time heat at all.

I'm thinking a ceramic heater would work, if I can convince my husband I won't burn down the neighborhood.

dice · March 2, 2011

You could use one or two brooder lights pointed at a stack
of bricks. The bricks would absorb heat from the lamps and
radiate it out into the mini-greenhouse. (I do not know if this
would be less expensive than a ceramic heater, either to buy
or to operate.)

Brooder lamp:
http://www.amazon.com/Designers-Edge.../dp/B000E8OTTQ

RayR · March 2, 2011

Lot's of good ideas, heating mats would definitely help much too. If you keep the soil temp around 60 or better and the air temp over 50 at night, you'll be OK.

kath · March 2, 2011

Last year I draped aluminum foil from the shop lights next to the shelving to enclose the seedings, reflect more light, etc. A heat mat inside of that, not directly touching the roots of plants, in addition to the lights, really warmed things up quite a bit. That way you wouldn't be trying to heat the entire space, as with a space heater. Folks use other things like cut up mylar emergency blankets, styrofoam sheets, etc. to accomplish the "enclosure".

erlyberd · March 3, 2011

Well, for a correctly designed passive solar gh the recommened gals per sq. ft. of southern glazing is 1-3 gal depending on climate.

Is there a way for you to just close off one little area of this gh to heat? Keep it low and long and insulate the north, east and west walls. Then add a night blanket. Like a gh inside a gh? With that type of setup and a heat source you'll be golden. With double coverage you won't need to turn on the heat until outside temps reach below freezing depending on if you had sun that day and how much thermo mass you have if any.

I'm sure you can work out something being so close to the house makes it that much easier. Good luck with the GH and the new home. Sounds like you picked a winner!

David Marek · March 3, 2011

Congratulations on the greenhouse. What are the dimensions? Make sure you nose around the undercover gardening section. Bottom heat is very effective, especially when the pots are in carrying trays. Heating the soil instead of the air allows for lower air temp- which means less heat lost through the roof. I use a fan forced electric heater (connected to a thermostat) in an 8 x 12 attached greenhouse to keep a minimum air temp of 60F. If the insulation blanket is not on at night, when outside temps go below around 20F I need 2 heaters on separate circuits. I do not have room in there for water barrels, or anything else that doesn't have chlorophyll, for that matter. I run it all year and the heat usage in April is negligible compared to December or January. I start tomatoes under grow lights in the basement, though.

Is your gas heater vented to the outside? Tomato plants are a good indicator for improperly burnt combustion gasses, usually noticed when they are close the heater.

b54red · March 3, 2011

Why not have someone who is knowledgeable check out the heater. Surely you know someone who is and engineer or even a good mechanic who could check to see if it is safe. If it doesn't leak and burns properly and isn't near enough anything that it could ignite why not try it out. I also have a small attached greenhouse and I now use a small propane heater in mine and have for years with no problems other than the cost of propane. I wish I had natural gas but live in an area where it is unavailable. I used to use electric heaters but became worried by the things running at full blast for hours on end when the nights were really cold and the heaters electrical cords would become so hot they would nearly melt. I even got a commercial grade 220 volt heater to use on the very cold nights but the power usage was through the roof but it did keep it warmer and didn't have to run constantly like the smaller heaters. The advantage to a small gas heater is it can put out so much more heat even when burning at a very low rate.

kevinrs · March 3, 2011

You can have a natural gas appliance like a heater checked for leaks for free by your gas company generally, check on that. My sister did that and they fixed a leak in her oven, (at the valve inside, little gas smell, as it collected in the oven, could have been a big boom situation if she'd turned it on when the gas concentration was right) and a bigger one at the valve for the gas lighter for the fireplace (not noticed due to high ceilings) in the 15 year old house she bought.
The worst they can do is red tag it as unsafe, and turn off the gas valve to it. Then you either get it fixed, or just don't use it, as you are doing now.

BlackestKrim · March 3, 2011

At what temperature should you heat the greenhouse at night? I have recently gotten a little greenhouse and was wondering how much it needed to be heated (if at all) if I used it over the winter to grow tomatoes. I am curious about the minimum temps for both young and mature plants.

erlyberd · March 3, 2011

BKrim,

It depends on how deep your pockets are and what varieties your growing. What are you getting for night-time lows?

I'd shoot for 50 degrees without knowing. But With cool-tolerant plants you could bump that down quite a bit I would think. Depends if there are flowers presently showing also. Some like Siberia claim to be able to set fruit at 38 degrees but I was'nt impressed with the flavor very much. Most of my plants were'nt overly effected by one 40 degree night that I noticed anyway.

platys · March 7, 2011

I'm probably overstating by calling it a greenhouse - its just a little room of mostly windows (but solid roof) off the garage. It's maybe 6 feet by 4 feet. Oh, and full of junk right now:

Mini greenhouse by knittergail, on Flickr

We bought the house from an estate - while the lights still work, I'm not sure its really been used since the 80s, when the husband died. It was full of the old storm windows and random boards when we bought it.

Here's a close up of the heater. As far as we can tell, the gas line runs under our backyard, into the garage. The garage isn't attached to the house.

Greenhouse heater by knittergail, on Flickr

platys · March 27, 2011

I finally got my seeds planted this weekend. I bought a heat mat, plus a temperature controller for it. The tray is inside now, happily cooking away at 80 degrees - my house is at about 67, so I think I'll be fine with getting +15 degrees of heat, at least - the thermostat keeps turning off the mat to keep it from going higher.

It's freezing in the Chicago area right now, but when I compared the outside temp to the inside temp of the "greenhouse", it was 17 degrees over the outside temp at 4:30 pm - that's without direct sunlight into the back, where the grow lights are. And, i didn't have the door shut or the lights on. So I think I'll be fine - my current plan is the heat mat, plus start out with enclosing the shelf with foil. If its particularly cold, I can put my ceramic heater in there.

I checked out the gas lines in my basement, and the line going out to the garage is closed shut.

March 1, 2011	#1
platys Tomatovillian™ Join Date: May 2010 Location: Naperville, IL Posts: 176	First time using my little greenhouse This is our first spring in our new house. The previous owners had built a little "mini greenhouse" off the garage - mainly, its a small room with mostly glass on 3 sides. It has a whole seed starting setup, including working shop lights and shelves. It was one of the selling features of the house to me. The previous owners probably used the gas heater that is built into the room. However, we've been advised to not touch the thing, given that it hasn't been inspected, and there's no reason to think it would pass inspection. So, I'm realizing that I'm going to have a serious cold problem. In May in my area of IL, the average night time temps will still be below 40, but not by much. I read that having the seedlings be cold can be good, but is 35-38 too cold? I'm assuming the shop lights will put out some heat. If I add heating pads, would that help? I know I'll have to start the seeds inside the house, no matter what. I have four cats, so finding a spot will be a challenge.

March 2, 2011	#5
dice Tomatovillian™ Join Date: Jan 2007 Location: PNW Posts: 4,743	You could use one or two brooder lights pointed at a stack of bricks. The bricks would absorb heat from the lamps and radiate it out into the mini-greenhouse. (I do not know if this would be less expensive than a ceramic heater, either to buy or to operate.) Brooder lamp: http://www.amazon.com/Designers-Edge.../dp/B000E8OTTQ __________________ -- alias

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March 1, 2011	#2
laspasturas Tomatovillian™ Join Date: Feb 2010 Location: Oklahoma Posts: 57	Lots of people who grow in hoop houses also use row cover inside for an added barrier from the cold. Something like that might work in your set up. I'm jealous, by the way! It would have definitely been a selling feature for me, too.

March 1, 2011	#3
puttgirl Tomatovillian™ Join Date: Aug 2008 Location: SW PA Posts: 281	Lucky you! I'd love it, too. If the area's not too large, I'd just go with a small ceramic heater. It doesn't have to be too warm, and you can get the heaters pretty cheap these days.

March 2, 2011	#6
RayR Tomatovillian™ Join Date: Jun 2010 Location: Cheektowaga, NY Posts: 2,466	Lot's of good ideas, heating mats would definitely help much too. If you keep the soil temp around 60 or better and the air temp over 50 at night, you'll be OK.

March 2, 2011	#7
kath Tomatovillian™ Join Date: Jan 2010 Location: zone 6b, PA Posts: 5,664	Last year I draped aluminum foil from the shop lights next to the shelving to enclose the seedings, reflect more light, etc. A heat mat inside of that, not directly touching the roots of plants, in addition to the lights, really warmed things up quite a bit. That way you wouldn't be trying to heat the entire space, as with a space heater. Folks use other things like cut up mylar emergency blankets, styrofoam sheets, etc. to accomplish the "enclosure".

March 3, 2011	#8
erlyberd Tomatovillian™ Join Date: Jan 2011 Location: CT Zone 5 Posts: 186	Well, for a correctly designed passive solar gh the recommened gals per sq. ft. of southern glazing is 1-3 gal depending on climate. Is there a way for you to just close off one little area of this gh to heat? Keep it low and long and insulate the north, east and west walls. Then add a night blanket. Like a gh inside a gh? With that type of setup and a heat source you'll be golden. With double coverage you won't need to turn on the heat until outside temps reach below freezing depending on if you had sun that day and how much thermo mass you have if any. I'm sure you can work out something being so close to the house makes it that much easier. Good luck with the GH and the new home. Sounds like you picked a winner!

March 3, 2011	#9
David Marek Tomatovillian™ Join Date: Jan 2010 Location: St Charles, IL zone 5a Posts: 142	Congratulations on the greenhouse. What are the dimensions? Make sure you nose around the undercover gardening section. Bottom heat is very effective, especially when the pots are in carrying trays. Heating the soil instead of the air allows for lower air temp- which means less heat lost through the roof. I use a fan forced electric heater (connected to a thermostat) in an 8 x 12 attached greenhouse to keep a minimum air temp of 60F. If the insulation blanket is not on at night, when outside temps go below around 20F I need 2 heaters on separate circuits. I do not have room in there for water barrels, or anything else that doesn't have chlorophyll, for that matter. I run it all year and the heat usage in April is negligible compared to December or January. I start tomatoes under grow lights in the basement, though. Is your gas heater vented to the outside? Tomato plants are a good indicator for improperly burnt combustion gasses, usually noticed when they are close the heater.

March 3, 2011	#10
b54red Tomatovillian™ Join Date: Sep 2009 Location: Alabama Posts: 7,068	Why not have someone who is knowledgeable check out the heater. Surely you know someone who is and engineer or even a good mechanic who could check to see if it is safe. If it doesn't leak and burns properly and isn't near enough anything that it could ignite why not try it out. I also have a small attached greenhouse and I now use a small propane heater in mine and have for years with no problems other than the cost of propane. I wish I had natural gas but live in an area where it is unavailable. I used to use electric heaters but became worried by the things running at full blast for hours on end when the nights were really cold and the heaters electrical cords would become so hot they would nearly melt. I even got a commercial grade 220 volt heater to use on the very cold nights but the power usage was through the roof but it did keep it warmer and didn't have to run constantly like the smaller heaters. The advantage to a small gas heater is it can put out so much more heat even when burning at a very low rate.

March 3, 2011	#11
kevinrs Tomatovillian™ Join Date: Feb 2011 Location: Littlerock, CA Posts: 218	You can have a natural gas appliance like a heater checked for leaks for free by your gas company generally, check on that. My sister did that and they fixed a leak in her oven, (at the valve inside, little gas smell, as it collected in the oven, could have been a big boom situation if she'd turned it on when the gas concentration was right) and a bigger one at the valve for the gas lighter for the fireplace (not noticed due to high ceilings) in the 15 year old house she bought. The worst they can do is red tag it as unsafe, and turn off the gas valve to it. Then you either get it fixed, or just don't use it, as you are doing now.

March 3, 2011	#12
BlackestKrim Tomatovillian™ Join Date: May 2009 Location: Austin, Texas Posts: 147	At what temperature should you heat the greenhouse at night? I have recently gotten a little greenhouse and was wondering how much it needed to be heated (if at all) if I used it over the winter to grow tomatoes. I am curious about the minimum temps for both young and mature plants.

March 7, 2011	#14
platys Tomatovillian™ Join Date: May 2010 Location: Naperville, IL Posts: 176	I'm probably overstating by calling it a greenhouse - its just a little room of mostly windows (but solid roof) off the garage. It's maybe 6 feet by 4 feet. Oh, and full of junk right now: Mini greenhouse by knittergail, on Flickr We bought the house from an estate - while the lights still work, I'm not sure its really been used since the 80s, when the husband died. It was full of the old storm windows and random boards when we bought it. Here's a close up of the heater. As far as we can tell, the gas line runs under our backyard, into the garage. The garage isn't attached to the house. Greenhouse heater by knittergail, on Flickr

March 27, 2011	#15
platys Tomatovillian™ Join Date: May 2010 Location: Naperville, IL Posts: 176	I finally got my seeds planted this weekend. I bought a heat mat, plus a temperature controller for it. The tray is inside now, happily cooking away at 80 degrees - my house is at about 67, so I think I'll be fine with getting +15 degrees of heat, at least - the thermostat keeps turning off the mat to keep it from going higher. It's freezing in the Chicago area right now, but when I compared the outside temp to the inside temp of the "greenhouse", it was 17 degrees over the outside temp at 4:30 pm - that's without direct sunlight into the back, where the grow lights are. And, i didn't have the door shut or the lights on. So I think I'll be fine - my current plan is the heat mat, plus start out with enclosing the shelf with foil. If its particularly cold, I can put my ceramic heater in there. I checked out the gas lines in my basement, and the line going out to the garage is closed shut.