Hmm, I believe the lid helps them to heat, and protects from wind temp.
Have you tried taping the saran wrap down? Duct tape would do it. I have a 14$ heat/embossing gun and I use grocery bags and others and shrink wrap them over my containers.

Define lid...

Milk jugs & 2L bottles shouldn't have them.

Other wide-open containers such as deli flats and dairy containers should have them with slits made.

Best way to do the saran-wrap thing: Cut the center out of the dairy lids (don't cut the edges where it hooks on the container). Put your saran wrap over the container, then put the lid on top of the saran wrap. Slice a hole or two. Use this same method for ice cream boxes (like the ones that Breyer's comes in that the lid is tight).

Deli containers (like harder plastic)- Slice one or two good size 'V' shapes in the lid. Fold back just a small amount of the tip of the V to start, then gradually fold back more of the V when you need to start doing so.

HTH!

Hey Sunny! Let's talk vocabulary. Lid, Caps, Tops. They get used interchangeably around here, but it's important to understand the difference. Lids and caps are most commonly the things you find on top of milk and 2 liter bottles. They screw or snap on. Lids and caps should be disposed of immediately.

Tops on the other hand are important for many reasons. Tops are the upper half of whatever container you sow in. They can be the upper half of a milk jug or soda bottle, or the saran wrap held in place on another container. They hold in moisture and they protect seeds from being eaten by birds. They can also prevent a seed washout in heavy rain. Tops stay on until germination is complete.

Another way to keep plastic wrap on is by using the lid that came with the container. For example, if you cut a hole in a Cool Whip container large enough to leave a 1 inch perimeter, you can lay plastic wrap over the container, then use the lid to hold it in place.

Keep those questions coming.

You can slide your container into a clear plastic bag and use something to tie it close or put excess under part of the container or use clothespins to keep the bag attached. Clothespins work really great and is what I mostly use now. I use bags from grocery produce, newspapers, etc.,any that are clear. I don't use rubber bands because in my area rubber bands break fairly quickly due to the elements.

Part of their purpose is to keep the moisture in the container as well as some heat. Ventilation helps keeps air flowing and allows water, rain/snow to enter as well as allowing excess heat to escape.

Thanks for the responses.
Some of the containers are Styrofoam and I broke the lids bad when trying to remove them. SO I can probably stick those in a grocery bag and not seal or tape it? If I do that it won't get any rain water though.

Sunny, you might try the plastic treat bags they sell at Dollar Tree. They are generally 24-30 for a dollar. Use the twisties, then snip little holes for ventilation.

Sorry, I forgot to say to put slits, holes in the top of the bags for ventilation and moisture as well as in the bottoms for drainage. I use the clothespins rather than twisties because it is quicker and easier for me. Especially with cold fingers.

Clear pastic and seed starting, well that just scares me..yeiks fried plants.
My favorite is milk jugs, but......
In my quest to be pot ghetto organized, last year I bought one of those Sterlite storage opaque containers, drilled holes in the bottom for drainage. Made plant plugs from 3in high plastic bathroom cups with slits on the bottom and filled the container. ( don't use paper ones, they don't hold up)
The lid that came with the container was solid white, tossed that and replaced with 5 mil semi clear plastic used usally for winter window coverings, attached with binder clips on the sides and made slits in the top of the "lid" for rain water.

This way I was able to get 40 some containers all in one big container and was easy to open with the binder clips.

this container also double dutied for some perennials I didn't get in the ground till fall, I filled 1/2 way with soil, planted the seedlings and let them in there the entire summer till I planted in the fall.

when I was looking at storage containers last week in WalllyWorld I saw they now have the opaque plastic shoe boxes with opaque, not solid lids for 1.88 each. I really like those to make mini greenhouses.

Essential to cover!
The best covers for me are the bags that grapes come in.
They already have holes in them, and they are the right size for the containers I use:
1/2 of a gallon plastic water bottle.

They just fit over the top.
They last from year to year.

When I cannot eat enough grapes, I use a stronger plastic like the kind that is sold to put over windows in the winter to keep out the drafts.
It is transparent, but much easier to work with than Saran Wrap. I would imagine Saran Wrap is too fragile to last thru the elements.

I poke holes in it, I secure with those big rubber bands that are sold 12 to a pack at Staples.

Sometimes the rubber bands last, sometimes not, but to me it is the easiest, and I don't mind buying more. I tried taping down the top of the plastic jug, some people do that with success, that did not work for me.

with rubber bands, I can easily open them up, as the weather warms, to see how dry they are. And the Plastic is easy to enlarge the holes, as it warms up.

Eat more grapes!