Covered Wagon.... plastic what?

I am setting up my first sfg and I'm trying to build a covered wagon but I have two questions.... so far. I tried to buy plastic to go over it at a big box store and was sent to the paint section. There were five or more different types of Polyethylene Sheeting with varying thicknesses.... I have no idea if this is the right thing to use nor do I know if it is what thickness I should get. Any suggestions?

Also, if I use a covered wagon, does this mean I can plant before my last freeze date? If so how much earlier? Should I be using the average frost date or safe date?

Thanks for any help... second year gardening ever and first time actually researching it first... lol.

Here's what I've learned so far....

6mm CLEAR contractor's plastic. You can buy thinner, but it's noticeably less durable on windy days, but it's fine, too. Yes, it's in the paint section. Buy it big enough you can close the ends by rolling and clamping the plastic. If you have a 4 by whatever garden, you likely need a 10 foot width of plastic to get enough overhanging the sides to weigh down with bricks or whatever. That's hard to visulize. I hope it makes some sense.

If not a wide enough sheet of plastic, you may need to cut some of the length off your PVC hoops. That will drop the height a bit and allow more plastic to reach the ground....giving you more overlap to put bricks on.

Yes, you can plant before your frost/freeze dates. However, you need to monitor the heat retention in your hoophouse. That plastic really stinks at holding the heat once the sun goes down. Your inside hoops and outside hoops temps will match very quickly......within minutes.

So, now we get into HOW to tweak things to hold in the heat overnight better. If you are just intereseted in keeping frost off, your job is likely done. But, if you want protection against a random 28 degree night, you need to tweak your covered wagon. You can do this in several ways...

- Floating row cover inside the hoops.
- Thermal mass....milk jugs (lots of them) filled with water to release their daytime heating slower than the air throughout the night. Really, though, I mean a lot of them.
- Combination of both. (Personally, this is what I did. I had the jugs in the squares around the perimeter of my garden and they held the row cover a little above the soil creating about a 12 inch layer of warmer air.
- Christmas lights. Some here have put their lights inside their hoops and kept things quite warm through some pretty cold nights. I can't offer any advice here because I haven't attempted this yet.
-Blanket over the top of the wagon. Again, not something I have done. But, I have seen it mentioned with success.

Bottom line is you need to really trap that warm air inside because a single layer of plastic won't. And, if you don't get sun for a couple consecutive days, you need to be extra vigilant because the hoops won't get too much warmer inside than outside. On a sunny day, I can get a 40-50 degree differential by noon. However, on a cloudy day, I get 10-15 degrees tops.

If your daytime temps get to 40, you may want to consider opening the hoops and letting things ventilate. The last thing you want is lettuce and spinach getting to 100 degrees.

Sorry this is so long. But, lastly, how to determine your new frost dates?

If you are trying to beat hard freezes consistently, and are successful after monitoring things closely, you can get a full zone of benefit from a covered wagon. What I did was went looking through the maps and found cities the next zone and looked up THEIR frost dates. It takes a little research because I found hardiness zones and frost dates don't always coincide.

I live in 6a, went to 7a, and found Ripley, TN. I live in St. Louis, MO. I really played around with frost dates from this site.... http://davesgarden.com/guides/freeze-frost-dates/index.php?q=63126&submit=Go and found one I thought was right. But, it's only a guess that will change any given year, of course, and I likely overthought it.

Hope this helped.

Thank you so much! It did really help!! I live in a desert so it's kind of random frosts at this point.... I'm ready to garden though! I've had friends who started last year in February, how, I'm still wondering.... Again, thank you! I'm anxiously excited about this new adventure in my own backyard.

krazikandiland wrote:Thank you so much! It did really help!! I live in a desert so it's kind of random frosts at this point.... I'm ready to garden though! I've had friends who started last year in February, how, I'm still wondering.... Again, thank you! I'm anxiously excited about this new adventure in my own backyard.

No problem. Stay excited. And, please report back about what you experience in your HoopHouse....good or bad. We are all still learning.

Also, search around. I have another thread called Hoop House Issues...Please Solve, or something very close to that. A bunch of us bantered around and it helped me tremendously to talk with others about my experiences, and ask questions.

That is the whole idea of this forum.