Cold Frame...Portable Greenhouse for seedlings.

seymour_man · January 6, 2017

I am not growing for market but I thought this question might be answered best here.

I am in Indiana zone 6a. I have always started my tomato, pepper and other garden seeds indoors under lights using a spare bedroom. I had enough stands and lights so I was able to start a couple hundred plants or so and keep them indoors until time to harden them off to plant outdoors.

I am losing most of the spare bedroom to my wife for her use (she is my best friend so its OK) but now I need a new plan. I will have 1 lighted 4 shelf stand with 2' x 4' shelves. That is still plenty of room for seed starting several hundred vegetables and flowers. But when its time to pot up they will need to go outdoors in early spring. I usually start things rolling around March 1 with some earlier and some later. Which means they will need to go outdoors a few weeks later.

I am thinking about a passive heated cold frame or portable greenhouse to be used only for spring seedlings 4-6 weeks a year. I might be building a permanent heated greenhouse but that is 2-3 years away.

Does any one have any suggestions on these things? Buying? Building one?
Brands?, etc.

Any advice is appreciated.

jmsieglaff · January 6, 2017

I bought this 5 years ago and have been very pleased. http://shop.readydogkennel.com/Auto-...-RGH-4322K.htm

I line the slides with spray painted black 1/2 gallon milk jugs (filled with water). I also built a polystyrene cover for it that is covered with a tarp (polystyrene foam boards are not UV stable) that I put on at night to retain heat much better. It is on my deck up against the house facing south. Empty it holds 4 flats, but with the 1/2 gallon milk jugs on the sides it holds 3 flats.

I use it to hold my cool season crops before they are planted out. And then once those go into the garden my peppers and tomatoes enter where they live for about 3 weeks until it is plant out time. The auto-vent is essential for me since I'm not home during the day. On windy days the auto-vent can flip around, so I secure it with a piece of twine to one of the milk jug handles so that doesn't happen.

It doesn't sound like this would be big enough for your uses, but they do offer a double sized one. Not sure our situations will line up exactly, but maybe the concept will be helpful.

rhines81 · January 6, 2017

You did not mention how handy you are or what sort of space you might have for this temporary outdoor set-up. I doubt it would be too portable, but it could be disassembled/reassembled each year.
For 100 plants, you could definitely use about 50 linear feet of preferably south-facing shelving. You could go with wider 18" shelving and double up and get away with 25 feet perhaps. One shelf at 2ft high and another at 4ft high and you are down to about 12 feet of south-facing wall.

3 steps:

1) Put 3 standard pallets (48"x40") on solid level ground, fasten them together side-by-side so you have a 40"x12ft platform and cover with 1/2" plywood.

2) Build a 6-8ft high 2x4 stud frame around it and incorporate (2) 12 foot long x 18" wide shelves on the south wall at 2ft and 4 ft high.

3) Wrap the entire thing with thick poly-film using staples, do the ceiling last to make it more drip proof. Make sure your open seam is on the back of the structure so you can untie it and walk in.

Your structure is built, you have the shelving you need and 12ftx22" of open space to allow watering and care. It will be heavy-duty enough not to tip over, but strong winds could shred the poly.

Dak · January 7, 2017

Quote:

Originally Posted by jmsieglaff

I bought this 5 years ago and have been very pleased. http://shop.readydogkennel.com/Auto-...-RGH-4322K.htm
.

Thanks so much for posting your link. Like seymour_man, I'm looking for a way to start my seeds outside this year. Since I want to be able to keep them in there for up to 3 months I found something else on their site that should work great for me, their 4 shelf mini greenhouse: http://shop.readydogkennel.com/4-Shelf-Mini-Greenhouse-IS-66402.htm
I've seen similar ones, but they generally look cheap to me. This looks like it will stand up to some use. Looks like a good company, though their shipping is much more than I usually consider paying.

So thanks for sharing your experience with this company and your suggestion to use plastic jugs.

Cole_Robbie · January 7, 2017

I make my high tunnels out of chain link top rail, connected with metal conduit fittings. Top rail is about $1 a foot, and you can build anything with it, structure-wise.

rhines81 · January 7, 2017

Quote:

Originally Posted by Dak

Thanks so much for posting your link. Like seymour_man, I'm looking for a way to start my seeds outside this year. Since I want to be able to keep them in there for up to 3 months I found something else on their site that should work great for me, their 4 shelf mini greenhouse: http://shop.readydogkennel.com/4-Shelf-Mini-Greenhouse-IS-66402.htm
I've seen similar ones, but they generally look cheap to me. This looks like it will stand up to some use. Looks like a good company, though their shipping is much more than I usually consider paying.

So thanks for sharing your experience with this company and your suggestion to use plastic jugs.

Dimensions are way too small for practical use for tomato/pepper plants anyhow... Overall dimensions: 66" H x 40" W x 20" D

10/20 trays need about 16" x 24" of space for breathing room. I have seen a bunch of small (and well designed) green houses that fall short on practical dimensions. Why the hell are they only 20" deep? I don't know why they do not design these for 48wx24d so you can comfortably fit 3-4 trays per shelf and close it up nicely. Come on, give me 4-6 more inches! 4 shelves with 66" of height???? If you are growing out tomato and pepper plants, you can only practically use 2 shelves (1-2' from the ground and another at around 3-4') ... these plants need some vertical space too. This might be great for a few trays of 4-6 week old seedlings, but then what? I think these are more suited for people that grow flowers and not vegetables.

Rajun Gardener · January 8, 2017

Go bigger for more plants!! Here's a cheap option with more space http://www.ebay.com/itm/8-Shelves-Gr...0AAOSwLa9UWfcJ

Farmette · January 8, 2017

I start hundreds of seedlings indoors in my living/great room on a 6 shelf metal rack unit that is 4 feet long. I attach my grow lights. When it is time to pot up and move outside, I have a Spring Gardner greenhouse that I put up on my deck. It's 6 by 8 ft., has zip doors on opposite sides as well as velcro windows on the long sides. I break down my shelf metal rack into two 3 shelf metal racks and put each one inside the greenhouse along the 8 ft. side. I can fit another shelf unit along the back. The greenhouse I bought at Blairs Farm and Fleet for under $200 and I had the metal racks and lights. So far, so good. I can put a portable heater inside along with a thermostat. The only thing is I wish I had bought the 8 by 10 ft. unit. They always say, go bigger and that is true. For the last few years, I have been starting at least 800 seedlings for myself and others. When I whittle that down, the 6 x 8ft. unit will be more than enough.

greenthumbomaha · January 8, 2017

Farmette, do you insulate the bottom or keep the "natural" floor. I used styro in mine and it helped keep the temp a few degrees warmer. Maybe the sun hitting the ground compensates for the cold being radiated form the earth.

- Lisa

Dak · January 8, 2017

@Rajun Gardener and @rhines81
Thanks to both of your for pointing out the shelf problem. Rajun, I looked at the one you linked and while I really like the price, I'm skeptical about that cover. What do you think of this one? It doesn't come with shelving, I can improvise that pretty easily, but the venting system looks like a great feature.

Rajun Gardener · January 8, 2017

I bought a bigger green house with that cover and it lasted 2 seasons but it was in the sun all year, I think you're gonna have the same problem with the one you posted and for that price you can get a bigger one. I'm warning you now, green houses are as addicting as growing tomatoes, once you get one, you'll want a bigger one. You can always replace the plastic as needed about every 4 years is normal even with good green house plastic.

Grow bigger!!!!

http://www.ebay.com/itm/New-Hot-Gree...EAAOSwcvdXO8vO

Dak · January 8, 2017

Go bigger! I started just looking at cold frames, LOL. At this point in my life I want this close to the house so space is a factor, I just don't have a lot of space if I factor in convenience and access to electricity, as I plan to use my heating mats. Got to say though, some of those double wall polycarbonate paneled greenhouses look awfully nice.

Rajun Gardener · January 8, 2017

Well I tried to help you make the plunge. LOL Harbor freight has some poly GH's. Did you see this one? It's small and has room for what you need. http://www.ebay.com/itm/New-7-x3-x6-...cAAOSwQaJXQ~sZ

Dak · January 8, 2017

I do appreciate your help and certainly can see how size can be a very slippery slope. I did look at Harbor Freight, let me see how well this works this year. At the moment, I see myself only using this until May, it will be too hot to do anything at all in a greenhouse over the summer.

Rajun Gardener · January 8, 2017

The summer heat is a problem for me too probably more than you. I use the GH from Sep-April to extend the fall season, over wintering plants, growing hydro tomatoes, starting fall seeds and raising Spring seedlings. It was a nice 78 inside there today with outside temps in the 40's. Good Luck with whatever you decide and have fun and a good season.

January 6, 2017	#1
seymour_man Tomatovillian™ Join Date: May 2007 Location: Indiana Posts: 48	Cold Frame...Portable Greenhouse for seedlings. I am not growing for market but I thought this question might be answered best here. I am in Indiana zone 6a. I have always started my tomato, pepper and other garden seeds indoors under lights using a spare bedroom. I had enough stands and lights so I was able to start a couple hundred plants or so and keep them indoors until time to harden them off to plant outdoors. I am losing most of the spare bedroom to my wife for her use (she is my best friend so its OK) but now I need a new plan. I will have 1 lighted 4 shelf stand with 2' x 4' shelves. That is still plenty of room for seed starting several hundred vegetables and flowers. But when its time to pot up they will need to go outdoors in early spring. I usually start things rolling around March 1 with some earlier and some later. Which means they will need to go outdoors a few weeks later. I am thinking about a passive heated cold frame or portable greenhouse to be used only for spring seedlings 4-6 weeks a year. I might be building a permanent heated greenhouse but that is 2-3 years away. Does any one have any suggestions on these things? Buying? Building one? Brands?, etc. Any advice is appreciated.

January 6, 2017	#2
jmsieglaff Tomatovillian™ Join Date: Jan 2014 Location: Southern WI Posts: 2,742	I bought this 5 years ago and have been very pleased. http://shop.readydogkennel.com/Auto-...-RGH-4322K.htm I line the slides with spray painted black 1/2 gallon milk jugs (filled with water). I also built a polystyrene cover for it that is covered with a tarp (polystyrene foam boards are not UV stable) that I put on at night to retain heat much better. It is on my deck up against the house facing south. Empty it holds 4 flats, but with the 1/2 gallon milk jugs on the sides it holds 3 flats. I use it to hold my cool season crops before they are planted out. And then once those go into the garden my peppers and tomatoes enter where they live for about 3 weeks until it is plant out time. The auto-vent is essential for me since I'm not home during the day. On windy days the auto-vent can flip around, so I secure it with a piece of twine to one of the milk jug handles so that doesn't happen. It doesn't sound like this would be big enough for your uses, but they do offer a double sized one. Not sure our situations will line up exactly, but maybe the concept will be helpful.

January 6, 2017	#3
rhines81 Tomatovillian™ Join Date: Mar 2015 Location: Zone 5A, Poconos Posts: 959	You did not mention how handy you are or what sort of space you might have for this temporary outdoor set-up. I doubt it would be too portable, but it could be disassembled/reassembled each year. For 100 plants, you could definitely use about 50 linear feet of preferably south-facing shelving. You could go with wider 18" shelving and double up and get away with 25 feet perhaps. One shelf at 2ft high and another at 4ft high and you are down to about 12 feet of south-facing wall. 3 steps: 1) Put 3 standard pallets (48"x40") on solid level ground, fasten them together side-by-side so you have a 40"x12ft platform and cover with 1/2" plywood. 2) Build a 6-8ft high 2x4 stud frame around it and incorporate (2) 12 foot long x 18" wide shelves on the south wall at 2ft and 4 ft high. 3) Wrap the entire thing with thick poly-film using staples, do the ceiling last to make it more drip proof. Make sure your open seam is on the back of the structure so you can untie it and walk in. Your structure is built, you have the shelving you need and 12ftx22" of open space to allow watering and care. It will be heavy-duty enough not to tip over, but strong winds could shred the poly.

January 7, 2017	#5
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	I make my high tunnels out of chain link top rail, connected with metal conduit fittings. Top rail is about $1 a foot, and you can build anything with it, structure-wise.

January 8, 2017	#7
Rajun Gardener Tomatovillian™ Join Date: Jan 2014 Location: Tomato Cornhole Posts: 2,550	Go bigger for more plants!! Here's a cheap option with more space http://www.ebay.com/itm/8-Shelves-Gr...0AAOSwLa9UWfcJ

January 8, 2017	#8
Farmette Tomatovillian™ Join Date: May 2009 Location: Wisconsin Posts: 985	I start hundreds of seedlings indoors in my living/great room on a 6 shelf metal rack unit that is 4 feet long. I attach my grow lights. When it is time to pot up and move outside, I have a Spring Gardner greenhouse that I put up on my deck. It's 6 by 8 ft., has zip doors on opposite sides as well as velcro windows on the long sides. I break down my shelf metal rack into two 3 shelf metal racks and put each one inside the greenhouse along the 8 ft. side. I can fit another shelf unit along the back. The greenhouse I bought at Blairs Farm and Fleet for under $200 and I had the metal racks and lights. So far, so good. I can put a portable heater inside along with a thermostat. The only thing is I wish I had bought the 8 by 10 ft. unit. They always say, go bigger and that is true. For the last few years, I have been starting at least 800 seedlings for myself and others. When I whittle that down, the 6 x 8ft. unit will be more than enough.

January 8, 2017	#9
greenthumbomaha Tomatovillian™ Join Date: Nov 2011 Location: Omaha Zone 5 Posts: 2,514	Farmette, do you insulate the bottom or keep the "natural" floor. I used styro in mine and it helped keep the temp a few degrees warmer. Maybe the sun hitting the ground compensates for the cold being radiated form the earth. - Lisa

January 8, 2017	#10
Dak Tomatovillian™ Join Date: Mar 2009 Location: CA Posts: 494	@Rajun Gardener and @rhines81 Thanks to both of your for pointing out the shelf problem. Rajun, I looked at the one you linked and while I really like the price, I'm skeptical about that cover. What do you think of this one? It doesn't come with shelving, I can improvise that pretty easily, but the venting system looks like a great feature.