If you can get 6-foot rolls, cut them in half with a hack saw +before+ you unroll it.

That makes it a lot easier to do.

I haven't tried them yet, but I was hoping that slitted row covers would accomplish the same thing without the work of having to vent them by hand.

Here is a link that might be useful: slitted row covers

I am going to try the California method because I think you can lower one or both sides and hoe the weeds for the month they will be under plastic. (I don't want to use plastic mulch.)

This method should be much less costly than a high tunnel.

can you use wider plastic and then slit it down the middle after its in place?

You might be able to find some high quality poly remnants
and use them year after year. I bought some from , I believe it was, grower's supply.

Perforated 6' plastic works best. Install over wire hoops spaced 4' apart and anchor with hoops 8' apart over top. You can access either side by merely pulling the plastic up....the outer hoops will hold it. Also pull up for extra ventilation if needed.
Anchor ends with a heavy stake driven into ground with plastic
pulled very tight and tied around stake. Double or triple the end hoops to handle the tightening load.
The two piece, open in the middle, is a disaster! I tried it.
Even a slight breeze balloons it open and pins/clips go flying. Handled carefully , cover can be re-used.
Good Luck!
Bud

How tall/wide are these if you're only using 6ft wide plastic? Only leaving on for a month (at beginning of season)? Not for season extension, just for early start? What crops? I tried Googling California hoop and just got basketball results ;-)

Bud - do you have a picture?

I still want to build a HT now that I have area leveled but this system sounds like it would work well for setting out early tomatoes, peppers, etc. at lower cost, and also better than the netting (would use row cover) with clothespins on hoops that I used for strawberries last year - how hard is it to open for picking, and would it keep the squirrels out?

Sorry everybody, I have been offline.

My low tunnels would cover just a single 30 inch bed. That would be one row of just planted tomatoes or a double row of peppers. And if I have enough plastic I would start squash/zuchini etc.

Thanks for the advice on the wind opening up the plastic. I can see that happening here in SE Ohio because I live in a windtunnel of a ridge valley.

Plan B is single 6 foot wide plastic squeezed between two wire hoops with the crest supported by a stout wire stretched between short stakes spaced 10 feet apart. For ventilation I would pull up one side.

These single row hoops are way cheaper than a high tunnel and I hope to use them for early season extension since everything is so short then. Also the low tunnels won't effect the row spacings of the raised beds.

I hope this makes sense. I'm not the best person for explaining things. I'm a retired engineer after all. LOL

A low tunnel design I have thought about for permanent beds goes like this:

Form and pour end walls in concrete, with heavy footing with rebar reinforcement. These would be in the shape of a
emt hoop and as short or tall as you want them.

Embed eyebolts in the concrete end walls when you pour it Place 4 or five of them in the shape of an arch.

Run wires between the opposite end eyebolts like a clothes line. Use a strong single strand wire and turnbuckles to make them very taught.

Hang plastic ,row cover, or bird netting, over the wires. Maybe put poly pipe over the wires, or pvc, or old hoses over the top wire.

Remove wires when they are in the way, and coil them up to use later.

If it sags, which it shouldn't if the endwalls are heavy enough, just put a hoop in the middle.

Could be done with very stout wooden end walls too.

Forgot to mention....clothes pins or spring clamps would be good to hold the covering onto the wires...can be buried at the bottom or just pinned the lowest wire.