As a general rule with native plants...when they would normally fall from the parent plant. You may or may not see any "babies" until next spring, though.

Most native plants need some kind of stratification before they'll start growing, so if you collect seeds now...plant them now, and let nature take it's course.

Here's some more info that may be helpful.

Here is a link that might be useful: Indian Paintbrush

plant them as soon as u harvest them. fresh!

froggy