I use the wire bread ties. I save them up from different brands and from different grocery store's produce twisties, and from trash bag ties too.They are free and you can use them from one season to the next. I use them just like Juli describes using the wires. I'm small-time so it works for me. When I run out of colors I just twist 2 different colors together and voila, a new color. My family has gotten real good at saving the different colors for me. It is surprising how many colors are out there.
If you enlarge this pic from last year, you can see a green tie in the lower left around a baby pod, look closely and you can see a white tie, and 2 blue ties as well.
