Thats the kind of visqueen I use on my cold frame. Although I have a cold frame that has a hinge on the top, kind of like a box, so I open my cold frame in the morning, and then close it in the evening.

If you're going to open the cold frame during the day then it shouldn't matter, but the "clear clear" plastic will just rip to shreads in a month or two when a storm comes up.

If you're dead set on the thin 4 mil crystal clear stuff, use a double layer =)

Ok thanks. That's what I'm going to do, I bought three hinges to put along the top and I'll open it during the day and close it at night, although for now at night, I'll probably bring the lettuce in. I just wanted to make sure this was the right stuff to use, it wasn't what I was expecting. Here's a link to the plans I'm using. It's only going to be 4' x 3' though.

Here is a link that might be useful: cold frame design

You should not have to start lettuce in a cold frame now in zone 5...safe to direct sow!

I bought my 6 mil plastic from an agriculture supply and it is treated to resist the sun. I expected it to last 5 years and it is now going on 8 years. Al

I had some left over that I had in the shed so I got that on the sides, front, and back. I didn't get the plastic on the top but the wood is together and I just need to add the plastic tomorrow.

I know to put seedlings outside they have to be hardened off first but do I also need to harden them off or put them in the cold frame gradually? I put 4 trays in the cold frame while I was working on finishing it so they were outside for about 4 hours today. Inside the cold frame they are protected from the wind but do I need to do something to protect them from too much sun?

The forecast for Monday is partly sunny and 58. Today it was partly sunny also, inside the frame in the sun it was 70 and that was without the top.

I think that is what I bought. Although in the 6 mil you can only get the 10x25 roll. But I got it at Walmart for $6 cheaper than HD. It's not completely clear but I think it will work fine.

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I�m a little confused. I thought this plastic would allow sun through the sides and front of the cold frame. Is it just supposed to allow light through? When I put the seedlings in this morning, some are shaded by the sides. Is that how it is supposed to work? I guess that is why I thought I needed the clear plastic, to allow sun through the whole thing.

Nice work! That looks awesome!

It looks as if your cold frame is facing to the east, with the back of it to the west. correct me if I'm wrong. At high noon the cold frame should have 100% direct sunlight inside, over all the plants. Yours looks just like mine, same plastic and all.

The back should be on the north, IE, the cold from should slope downwards toward the south. However, there should be plenty of light that gets in the cold frame through the plastic sheeting. I know it doesn't look like it, but the dull light is perfect for brand new seedlings (like a week old, yours look older than a week)

At the bottom of your last picture, the lettuce looks like its getting good light through your plastic, is the wooden frame itself shading the other guys in there?

and to answer you about hardening off, seedlings only take me at most 3 days to harden off. I leave them outside in the cold for an hour and then bring them in, and the the next night increase the time by a couple hours. By the third night if it isn't too cold (like below 45) I'll leave them out all night. In a cold frame they should be well ready for a night outside in a windless cold frame.

The real bad thing about hardening off isn't the green leafy part of the plant getting cold, its the roots, which are susceptible to shock. soil temperatures, even near the top inch stay pretty even keeled, and change gradually. leaving a plastic potter out overnight meant the root system has to go from 60 or 70 degree soil to 40 or 45 degree soil in the space of a few hours.. its a tough trick to turn if they aren't used to it.

Lettuce will germinate right down to freezing temperatures, its incredibly cold hardy. while it takes months at 33 degrees to germinate, the plant itself doesn't need to be hardened off, at least not cautiously so. give it a couple hours in the nighttime cold and then they'll be ready to stay outside. I've never lost a lettuce seedling before, and I've forgotten more times than I can count. I did lose a couple tomato starts to shock one year though...

Which part of zone 5 do you live in Chele? If I may be so bold as to ask. I'm on the southern edge of 5, almost to zone 6.

Sorry for being a chatterbox.

Here is a link that might be useful: My blog, if anyones interested

You are a step ahead of me, but a zone ahead of me too. I was planning on putting one together last weekend, but didnt quite get to it, and we have 4" of snow predicted for Tuesday so waiting is probably good.

Are you planning on putting any kind of heat sink in there?

Timing on hardening off depends so much on your weather and the placement. I have a screened in porch (screen roof too) which is perfect. It softens the wind and the sun enough that even on the first day of hardening off, if it is close to 50 or above I can leave them all day. The past few days I have had to leave everything inside, so the hardening off will start all over again next week.

Thanks Chris. Unfortunately I didn't get the top finished last night. I had screwed the frame to a piece of wood i attached to my porch post and once I tried to put the lid on it was hitting the wood so I had to take it off and cut the wood so there was enough clearance. I did get the hinges marked and installed so tonight all I have to do is add the plastic to the top.

The front is facing the south. Those pictures were taken at 4pm Sunday so on the 2nd one, the sun was behind me and I'm most of that shadow. The frame is only 2x2 so it should not be blocking that much of the sun. I own a duplex so luckily I'm on the side that faces south.

I understand what you mean about the plastic diffusing some of the sun. I thought about it at work yesterday and if it were completely clear plastic, they would probably get fried in there.

The reason I ask about gradually putting them out is that while I was working on this over the weekend, I had brought the lettuce outside. The bigger ones did fine but my younger ones were sitting on the shed floor with the door open to block the wind but give them some sun. They weren't out long but I noticed a few of them had black leaves so I thought the sun had fried them because they were too tiny and not ready for it. It was cloudy off and on though so maybe it was something else.

Unfortunately we are getting rain today and tomorrow and since I don't have the lid on yet, I don't think they can handle pouring rain directly on top so they are staying inside today. One good thing is that they have been growing in my basement where it is cool so they haven't been exposed to temps much over 60, more like 55.

I'm in southern NH, about 45 minutes north of Boston. I like your blog, btw. I wish I had all that space!

I love New Hampshire! Your state motto gets me every time: Live free, or DIE!!!

I haven't heard of lettuce turning black before, I'm stumped. I usually try and get my seedling trays outside for a few hours the very first chance that I have sun and temps above 50 though, so I wouldn't be the one to ask.

I live about 4 hours south of chicago, and this last weekend they had 3 inches of snow. I think if I lived much more north than zone 5 I'd start to twitch if I had to deal with snow on April 18th.

Our last snow was April 1st. Heavy wet snow. Of course later that afternoon it all washed away and the next day was around 60 I seem to remember. That's NH! One year we had snow in May.

I wasn't planning on heating it but by the time the end of the season comes, who knows? I was only going to use it to harden off the seedlings and maybe grow some lettuce in the fall. I don't know how well it will hold up to the snow around here so I was going to take it down and put it in the shed for the winter.

I had some of the Bibb lettuce with leaves that turned black, maybe from too much watering. I didn't notice these leaves before I put them outside so I don't remember if they were like that before or not. Some of them were coming in dark and then they faded back to green. Plus some of what I have growing is red looseleaf.

The trays that you see in the frame are only 1/2 of what I have growing just for lettuce. I have 3 more trays in the basement still under lights. Plus the peppers and tomatoes. I figured some would die so I planted extra and now I'm running out of room. The other day was so warm in there I think I could have put some of the peppers in there to give them extra light and brought them back in when the sun went down.

I just started a cold frame box woth the 6 mil visqueen. I fot a slight cut in it. Is there a fod way to repair it? Can I duct tape a little piece on top of the slice? Or is it better to leave alone.