Q:

Using upside-down plastic cups as outdoor seed/seedling protection?

I have a little problem - somebody is eating my Echinacea's seed that I sow outdoors. As recommended, they are just placed on the ground, they germinate way easier if they have light. Their length is 2-3mm, fairly large seeds that I gather are too heavy for ants. I guess it might be birds that are having a healthy meal of Echinacea's seeds.
Does it make any sense to protect each seed by covering it with an upside-down positioned transparent plastic cup (used for human parties, etc.)? If yes, should I poke a hole for ventilation, so that I don't cook the seeds?
Some similar ideas can be found here, but this is for indoor seed starting.

A:

I would have thought plastic cups would blow away very easily in even a medium strength wind, as well as being fairly easily knocked over by determined birds; and yes, ventilation could be a problem, along with conditions inside the cup being a lot warmer than outside, meaning, once germination occurs, your seedlings will be shocked by the temperature once you remove the cups.
You could consider just sowing more so the birds have their share, or spreading any kind of seed elsewhere, but not too far away, that the birds like in an attempt to distract them from your Echinacea seeds. Alternatively, row covers or cloche like covers https://www.rhs.org.uk/advice/profile?PID=904 would do the trick, but again, sudden exposure to outside temperatures on germination could be an issue if outdoor temperatures are still low.

