Lynn,
You'll find the plastic ones will STICK TO YOUR SEED and it's tough to get them out of the envelope. Glassine is a treated paper and the seed seems to repel off from it so it facilitates planting. If you can't find glassine envelopes, you can use coin envelopes although you want to fold them and keep the seed towards the bottom as the seeds seem to want to come the top of the envelope. I sometimes pack the glassine envelopes in coin envelopes, because the glassine envelopes are rather flimsy.
I keep forgetting that I've done this for 50 years and I think everyone knows these things! I had a very good teacher in Polly.
Kevin
