William L. Rose wrote:
"simy1",

With your 100' x 12' vinyl, you get a tunnel, that, in a perfect world,
can be no more than 3.82' tall, with a width of 7.64', right?
Practically, what is it? What grade and o.d. PVC pipe do you use for the
hoops? How many and what kind of clamps do you use, and where have you
found it most advantageous to place them? Double clamps? What's that?
Any special fold in the vinyl to seal the tunnel? What important
question didn't I ask?

Yes, the tunnels are low enough that you can crawl under. The beds are
about 25 ft long, and 4ft wide, so one sheet, cut into three, covers
them all with a few feet of waste. You need the sheets to be several
feet longer than the beds to tuck the ends properly.

You buy the PVC pipes at Home Depot that are, from memory, 3/4" thick.
You also buy the 100X12 rolls of clear plastic from the Paint section.
I prefer 4mils, but 6 or even 2 will usually do (I have tried all
three). The PVC pipes are 12 ft long. You cut them at an angle at the
tips, bend them, and stick them one foot into the ground on either
side. Total hoop length: 10 feet.

You can either put a hoop every four feet, which makes it a bit
difficult to maneuver a wheelbarrow, or every 7 feet, like I do, and
them put an extra pipe on top of the hoops for extra strength, secured
to the hoops with cable ties and a screw to avoid slipping. The top
pipes are connected to one another with PVC cement and a connector,
exactly as if you were building your plumbing.

Once you have all the hoops in place, and I leave them there, summer
and winter, you garden the beds normally until it is time to cover
them. The clamps can be found at Territorial Seeds and are half
cylinder that clamp onto the pipes tigthly, grabbing the plastic. They
are excellent. The one foot of plastic on either side (12-10=2) can be
held down with bricks. The ends, too, can be held down with bricks. The
secret to keep the tunnels going in windy weather is to make sure as
little air as possible comes in. Specially the ends, I put down a
continuous line of bricks to eliminate air leaks. If there is snow on
the ground, no air comes in and the seal is perfect.

The plastic I am suggesting is not UV-treated and is not indicated for
summer use. In my case, I use it for about 3-4 years, and typically I
toss it due to various mechanical tears, like when I try to get ice off
of it. There is negligible UV degradation in the winter. I cover on the
Thanksgiving weekend and uncover on April 1.


So that give you an ideal maximum protected surface area of 352.79 sq.
ft. with no vinyl to lay the bricks, concrete, heavy somethin' on. What
is the reality? What measurements do you have for height, width, and
usable surface area in your green house?

How is the accessabilty? I'm about 6'2" and 250 lbs, Am I going to need
a mechanic's platform dollie to get in and out of the tunnel?

It will be a bit harder for you to crawl under for winter harvest.
Undoing a tunnel is a chore,
so in the winter I harvest once a week, filling a couple of buckets of
greens. I undo only a section, on one side, then get under the plastic
on my knees. You should, like I do, get organized and have the greens
laid out so you harvest one section at a time. That is, if you have
carrots, beets, radicchio, and collard, you should have one row of
each, so you only need to uncover that section for a complete harvest.
Then there is no need for crawling up and down the bed, and no need to
uncover more than one section. Opening a section means removing the
clamps on two consecutive hoops on one side only. The plastic will have
enough slack to let you knee under it.

Tunnels are much better than greenhouses. They are cheaper, much warmer
for the same insulation, the thermal ballast is the soil itself (you
must not mulch), and they never run out of CO2, as greenhouses do,
because soil with high organic content will give off plenty of it. In
Michigan, the soil under the tunnels freezes for time periods of order
one or two days, but one sunny day is enough to unfreeze it. Outside
the tunnels, the soil freezes for about 10 weeks straight. I have two
hoophouses as well, but for a starter, tunnels are the best. Also, if
you seed under the tunnels in march, stuff will come up much earlier.


Sorry for so many questions but I already have enough chores and I'd
like to avoid re-inventing the wheel.

Thanks for your time,
- Bill

In article . com,
"simy1" wrote:

James wrote:

Huh? A PVC pipe for each hoop costs $1.60. 100 feet of 12 ft poly costs
$27. The clamps will cost you another $20, and you have to have some
bricks to hold down the poly on windy days (concrete chunks will do as
well). If treated well, the poly lasts three years and the clamps and
hoops last forever. You are looking at $15 per winter harvest.

Works if you don't live in a windy area. It's easier to hold down the
poly than to keep it from tearing. Hoop tunnels 2' or 3' may work
better in windy areas.


I live in a fairly windy area. It took me a couple winters to get the
tunnels down pat. You need clamps, double clamps at the end of the
tunnels, and a smooth tunnel with some poly laying on the path, wieghed
down by bricks, so that no air can get inside. I never had a blowout
when there is deep snow, it seals the tunnels perfectly.