I use easily moveable metal hoops and sheet plastic for a cover.

For my purpose I need a cold frame that lets me open and close the top to avoid freezing or frying seedlings. It also functions as a raised bed. The hoop scheme is mainly to zone-push planted crops, right right?

I use the hoops to carry winter lettuce through the winter. On warm days I open the plastic a little.

Look for Charring wood technique.

I use the boards of used free pallets. Burn them over a charcoal grill, or a fire pit, then paint them with free used cooking oil from a local restaurant.

My raised beds from these boards had working several years for now without any damage.

Plain, untreated pine lasts 10 years here as raised beds. Though I'd prefer Suzy's concrete blocks.

A person after my own heart. Avgusta, that's generous , not to mention environmentally friendly plus saving material from going into landfill.

If you need something now and it is fast. Straw bales. If you bag them tight in large contractor bags, they can last a couple years. But if you just want to give yourself some time to build something more proper, unwrapped bales stand up strong over a winter.

Do be careful with using pallet wood. They have markings on them to indicate if they are heat treated (HT) or kiln treated(KT) or debarked(DB)- all OK. But if they have markings on them like MB- that's a pesticide and toxic. It was banned in 2010, but sometimes still turns up. International stamps can be treated, so safer not to use those. Completely unmarked ones are likely domestic. Otherwise, the charred wood thing is really a wonderful thing.

https://extension.oregonstate.edu/gardening/soil-compost/pressure-treated-wood-raised-bed-construction-willamette-valley

I personally wouldn't hesitate to use pressure treated wood for building the cold frame. It's cost effective and rot resistant. You can read more about it at the link above.

I wouldn't use pallets. They can be a nuisance to take apart and their wood is usually thin, warped, or split. And even if the pallet was only heat treated you can't really be sure that oil or other random chemicals weren't spilled on it at some point.

Rodney

Pallets are used for delivering diferent things. I 've found mine on a local craigslist, a facebook marketplace; they 've been used for delivering horse food bags. The boards were thick and fresh, smelled nice like fresh cut pine, to disassemble them wasn't been difficult, a hammer and a crowbar did it easy. It was good physical exercises and free. Do not need to pay for a gym :))

If I use cement blocks, how do I make the top tilted toward the sun? I guess i make the slope part of a wooden frame that fits on top?

You can slope the 'foundation' the blocks sit on. So the blocks are set on a slope.

You can build a more complicated wooden frame if you’re handy - or you can shovel out a sloped base before you lay the blocks. I’m handier with a shovel than a saw 😬

PVC frame then pex curved for roof with clear plastic over it. Very cheap and lasts a long time light and easy to move. Only pic I have is them with a blanket over them on a cold night. I build a square base with 2" pvc then in middle on 2 sides a "T" with 2" pvc up and then top middle 2" pvc to other side. Arch pex at 90 degrees from base, over top then down to other side. Easy to move cheap and works fantastic.

Do you need it to be tiltled? My cold frames were just four boards (not sure what kind of wood but I'm pretty sure they weren't cedar) put together with those L-shaped brackets. Old storm windows I got free off of craigslist for the top, laid just flat on top.

The beds worked for me for five years or so, and that length of time was only because I stopped growing greens over the winter. I still have the wood - not in fabulous shape but still usable for probably a few more seasons. I use the frames now for my dahlias in spring - put the potted up dahlias in the frames on the driveway and cover with windows for added heat.

:)

Dee