I could be wrong but I don't think Monarchs care much about spacing. lol I tend to let Mother Nature take its course too. The strongest plants will survive and a lot of the smaller ones will die. If you'd rather have a few large plants that flower well, you may need to thin them out. If your main goal is foliage for the monarchs, I'm guessing it doesn't matter how thick they are.

Are there other types of plants mixed in with your milkweed? If so, they may get crowded out.

Which milkweed do you have that's reseeding so heavily?

Did you still get your certificate?

Christie,
Thanks for the reply. Yes, I have my certificate. I just want to make sure I'm providing the optimal conditions for diverse wildlife. I have a mix of Asclepias incarnata, tuberosa, and another called "Red Milkweed" from Seed Savers Exchange. The incarnata is the one that reseeds so vigorously. I did have a horrible infestation of aphids this summer, so I don't know if that could be due to overcrowding, or if it's just the weather/humidity/cyclic changes, etc. I guess I'll wait to see how next year goes. This was by far my best year for Monarchs, though they were here and gone very early. I don't think I saw a single Monarch after the first of August, and that's about when the aphids really took over.

Oh, well. We'll see. Thanks again.

Martha