How much warmer are they? - Page 2

Mudman · May 17, 2012

Quote:

Originally Posted by Jaysan

I am considering a cold frame to start seedlings in instead of indoors under lights.
If it would keep enough warmth to work starting about mid March, and it can get below freezing in mid March in southern VA, I think I could do it.

Anyone use theirs for that purpose?

I think this would definitely work for you. If it is well insulated you can easily keep it warm enough in March. I can, and I live in a much colder climate than you. And if the forecast ever looks really bad you can cover it with a blanket or add a light bulb etc.

Tracydr · May 17, 2012

You can also add heat mass with water bottles and other types of high mass items like rocks.

habitat_gardener · May 18, 2012

I've started tomato seedlings in mid-March in a cold frame: bubble wrap over a wire frame (tomato cage placed horizontally), surrounded by gallon water bottles. It usually doesn't get below freezing in March, though it's often in the low 40s at night. (Right now it's about 53F, and it's supposed to get down to 45F tonight.) They germinate and grow slowly.

Jaysan · May 18, 2012

I might have to give it a try next year.

Lcottomsvcs · May 19, 2012

I had a grandfather who started all of his cold-crop seedlings in the cold frame. By this I mean the broccoli, cabbage, etc. I do not remember him starting the tomatoes there, but my memory is not perfect. It seems that the limiting factor would be hours of sunlight available in the cold frame in March. Would the seedlings get too leggy? Just wondering.

Mudman · May 19, 2012

Quote:

Originally Posted by Lcottomsvcs

Would the seedlings get too leggy? Just wondering.

Mine were getting leggy soon after I started them indoors. I moved them to the coldframe and they got plenty of light and got stocky because of the wind they were exposed to when it was open. I will say they are a challenge to keep watered once they get bigger. With the wind and high heat on some days they dry out very quickly. My first year using the cold frame I cooked a lot of seedling.

tgplp · May 29, 2012

My hoophouse can get really hot, depending on if it is sunny or not. A couple weeks ago, when it was 70 degrees for two days, my hoophouse got to 110 degrees inside! Yikes! When I opened the door, a wave of humidity hit me, it was like a sauna! I had to open up the door and window for a long time to cool it down in there. Poor lettuce plants.

Unfortunately, the hoophouse has been causing my tomato plants a lot of stress and yellowing of their leaves. I think it is because it gets really hot in the hoophouse during the day, and then plunges at night. I took a Green Zebra that was completely yellowed and dead looking out of the hoophouse for a week, and now it is green, lush and healthy again. Weird, huh?

Taryn

Granite26 · May 29, 2012

I had more trouble with heat in my makeshift "greenhouse" (some 2x4's and plastic) this year than I did with cold. In the past I had many more issues with them getting leggy under grow lights. It was a non-issue out in the "greenhouse" and in the sun provided they had space to grow and were not cramped together. I constructed this to start my seedlings and it has worked well. I only grow out about 3000. I germinate them inside my heated shop and then move them out when they get established some and have true leaves.

Another big benefit of this mild and early spring was that I had started some toms @ the first of the year and moved them out to the house in March and enjoyed my first ripe ones last week.

Cole_Robbie · July 18, 2012

I built a 14x48 high tunnel over the winter. I put in a gravel floor and used it to raise plants. The covering is a double layer of 6-mil poly inflated with a blower. The ends are a single poly layer. We bought a Clearspan kit, but it basically only comes with the metal pipes and brackets. The baseboard is 2x6, the ends are 2x4s, and the roll-up sides require a 2x4 down each side. All the lumber is treated, which was a pain because I had to paint it.

To answer the original question of 'how much warmer are they?" the answer is of course 'it depends.' On a sunny day with little wind, I got as much as 50 degrees of solar gain. On a cloudy day, I still got about 30 degrees of gain. That part was great.

What was not great was trying to heat a poly structure at night. I used wood heat and built a remote tin shed to house the furnace. I packed a giant furnace with wood three times a night and made a fire so hot that I couldn't hold my hand over the air vent coming into the greenhouse. I think the best I ever did was about 17 degrees above the outside temp, typically it was 12-15 at the most. The r-value of poly just stinks. Even with a double layer it's like 1.6. A typical 2x4 wall in a house uses R12 and ceiling takes R16. Plus with the roll-up sides, it is hard to seal out the wind.

You have to ventilate anything you cover, and it is remarkably easy to cook everything when the sun comes out. The smaller the structure, the faster it will heat up in the sun. If you have high humidity it actually helps plants tolerate it when it gets too hot. I had a trough of fish in the greenhouse and used the tank's aeration to create humidity. Wood heat tends to dry air.

meadowyck · July 18, 2012

cole robbie have you thought about the water barrels to help with holding the heat at night? or there is something new that I was just reading about and it is the same type of principle, they have this what looks like a flat container that fits behind in the side and runs the length of your green house you fill it with water and it aids in gathering the heat during the day and releasing during the nighttime. I'll go look for the link, I think I saved it, and come back and post it.

Cole_Robbie · July 18, 2012

Thanks, but I researched it extensively. Mass is good, because it holds heat. That's part of why I put in so much gravel. Water barrels would work for me, because my heat energy is almost free in the form of a wood fire. Water is not a good idea for people heating with propane or electricity at night, because the water becomes a heat sink after the air warms up faster in the morning. Your expensive heat would then have to work harder to raise the temperature than if the water barrels were not there.

I had a lot of great ideas, but most of them cost too much money. Using the wood furnace to heat water instead of air would be smarter, but I did not have the money to do it. I was given the forced air wood furnace for free. Farm-tek has the long water bags you are talking about, but once again the issue for me is cost.

May 19, 2012	#20
Lcottomsvcs Tomatovillian™ Join Date: Apr 2012 Location: Southern Indiana Posts: 123	I had a grandfather who started all of his cold-crop seedlings in the cold frame. By this I mean the broccoli, cabbage, etc. I do not remember him starting the tomatoes there, but my memory is not perfect. It seems that the limiting factor would be hours of sunlight available in the cold frame in March. Would the seedlings get too leggy? Just wondering. __________________ Gardening is not a rational act. Margaret Atwood

July 18, 2012	#25
meadowyck Tomatovillian™ Join Date: May 2012 Location: Brooksville, FL Posts: 1,001	cole robbie have you thought about the water barrels to help with holding the heat at night? or there is something new that I was just reading about and it is the same type of principle, they have this what looks like a flat container that fits behind in the side and runs the length of your green house you fill it with water and it aids in gathering the heat during the day and releasing during the nighttime. I'll go look for the link, I think I saved it, and come back and post it. __________________ Jan “Do what you can, with what you have, where you are.” -Theodore Roosevelt

May 17, 2012	#17
Tracydr Tomatovillian™ Join Date: May 2011 Location: Laurinburg, North Carolina, zone 7 Posts: 3,207	You can also add heat mass with water bottles and other types of high mass items like rocks.

May 18, 2012	#18
habitat_gardener Tomatovillian™ Join Date: Apr 2008 Location: California Central Valley Posts: 2,540	I've started tomato seedlings in mid-March in a cold frame: bubble wrap over a wire frame (tomato cage placed horizontally), surrounded by gallon water bottles. It usually doesn't get below freezing in March, though it's often in the low 40s at night. (Right now it's about 53F, and it's supposed to get down to 45F tonight.) They germinate and grow slowly.

May 18, 2012	#19
Jaysan Tomatovillian™ Join Date: Apr 2012 Location: Virginia, USA Posts: 167	I might have to give it a try next year.

May 29, 2012	#22
tgplp Tomatovillian™ Join Date: Jan 2011 Location: Pacific North West, zone 8a Posts: 510	My hoophouse can get really hot, depending on if it is sunny or not. A couple weeks ago, when it was 70 degrees for two days, my hoophouse got to 110 degrees inside! Yikes! When I opened the door, a wave of humidity hit me, it was like a sauna! I had to open up the door and window for a long time to cool it down in there. Poor lettuce plants. Unfortunately, the hoophouse has been causing my tomato plants a lot of stress and yellowing of their leaves. I think it is because it gets really hot in the hoophouse during the day, and then plunges at night. I took a Green Zebra that was completely yellowed and dead looking out of the hoophouse for a week, and now it is green, lush and healthy again. Weird, huh? Taryn

May 29, 2012	#23
Granite26 Tomatovillian™ Join Date: May 2009 Location: Western WI Posts: 359	I had more trouble with heat in my makeshift "greenhouse" (some 2x4's and plastic) this year than I did with cold. In the past I had many more issues with them getting leggy under grow lights. It was a non-issue out in the "greenhouse" and in the sun provided they had space to grow and were not cramped together. I constructed this to start my seedlings and it has worked well. I only grow out about 3000. I germinate them inside my heated shop and then move them out when they get established some and have true leaves. Another big benefit of this mild and early spring was that I had started some toms @ the first of the year and moved them out to the house in March and enjoyed my first ripe ones last week.

July 18, 2012	#26
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	Thanks, but I researched it extensively. Mass is good, because it holds heat. That's part of why I put in so much gravel. Water barrels would work for me, because my heat energy is almost free in the form of a wood fire. Water is not a good idea for people heating with propane or electricity at night, because the water becomes a heat sink after the air warms up faster in the morning. Your expensive heat would then have to work harder to raise the temperature than if the water barrels were not there. I had a lot of great ideas, but most of them cost too much money. Using the wood furnace to heat water instead of air would be smarter, but I did not have the money to do it. I was given the forced air wood furnace for free. Farm-tek has the long water bags you are talking about, but once again the issue for me is cost.