If you work somewhere that buys the big plastic canisters of coffee (typically 2# and 3# sizes), the empty canisters make ideal temporary planting pots simply by drilling several 1/2" holes in the bottom for drainage. I've started numerous small red oak trees by filling the empty canisters with a 50/50 mix of plain soil and potting mix, adding an acorn snuggled in about 3/4" deep and then setting outside for the duration of winter. The plastic weathers well and can be reused several times.
Steve
Just an FYI for planting pot substitutions
I use all kinds of plastic containers, including large yogurt and large styrofoam cups, it is all good.
Great idea, Steve! I use large yogurt and sour cream containers, but my container of choice is a 16 oz solo cup.