Everything.
I've seen old boots, blue jeans, and broken down cars turned into containers. Practically anything could work if you get creative enough!
Funkiness aside, there are some pretty good standbys that thrifty container gardeners fall back on often...
- Food grade buckets. Sometimes you can get these for free from food establishments, and they're a good size for plants that need a little more room to spread their roots.
- Big plastic tubs. Again, these can come in good sizes for plants that need legroom. Some people have also converted them into DIY Earthboxes.
- Trashcans as huge planters. Some of the larger tomato plants could even flourish in a big enough trashcan.
- Two-liter bottles. Check out this older post wherein I illustrate how to turn one into a pot with drainage.
- Plastic butter/spreadable cheese/yogurt containers, for smaller plants. Reserve the lids to use as water trays, but be sure to water slowly to avoid overflow.
- Soda bottle, upside-down, as a DIY Topsy Turvy. Is there nothing these plastic beauties can't do?!
- Really ugly pots that you already have or find free/cheap.... just turn them upside down and spray paint the pots to spiff them up. (Avoid getting paint inside the pots.)
If you want to find "real" pots at good prices, there are usually plenty of cheap options at discount stores like Big Lots and Wal-Mart. The dollar tree often has really cute little pots, but they usually need to have drainage holes drilled in them. End-of-season sales are a great way to find deals at local businesses, which we should all support whenever we can.
Plastic is usually the cheapeast option... But if you'd like to avoid plastic, terra cotta is probably the cheapest way to go.
And take care of your pots so you don't have to spend money replacing them. Put them away when not in use (especially over winter) and treat even the plastic ones as breakable.
I know there are a million and one other tips out there, so please share yours!