I use half gallon milk jugs whenever I can get them..they are just fine! I imagine the selzer bottles will be fine too. Just plant a little less seeds than a 1 gallon!!
Joann

So size doesn't matter... ;) What about color? I know people use styrofoam cups in baggies, and someone mentioned white milk jugs with windows put in.

I have several `dark red plastic coffee containers, and wonder if they will work with a clear cover. Has anyone used something like this-- would they overheat?

Thanks for all the advice, I'm glad I can use them since I have so many. Silver cat I would think that not enough light would reach the seeds in the red containers only high noon sun would reach them. That's just MHO. Those red containers are great for scooping out soil from the bag tho!

Hi ten steps and silver cat.

I LOVE the 1/2 gallon milk containers, wish i had a truck load of em.
I cut mine lenght ways,you can get more seed in that way.

Silver cat, I have used the red coffee cans also, no problem with mine.Don't use the black lid that come with it.
I use a clear piece of plastic i buy from the fabric store,over in the tablecloth section.

This year, i used cardboard boxes,I placed a 12-16 oz.plastic cup in each corner,layed my 1/2 gallon containers in the box,side by side,and covered the whole box with one piece of plastic,the cups hold the plastic high enough for head room for the babies to grow.
I am sure by the time i am ready to plant, the boxes will be ready for the recycle,but will last for what I am doing.Good luck,have fun,and I wish I had your milk cartons.:0)
cAROL