No! No! No! It's not done by squirrels or rabbits or groundhogs. It's a weevil (the "Sunflower Head-Clipping Weevil). I removed the one below from my purple coneflower and brought it in the house for a picture. I also killed 20 of his friends. What you have to do is walk around your garden and when you see a flower deadheaded 2 inches from the top, put your hand (or cup) underneath the flower and squeeze. These weevils will fall out into your hand or cup, and you can kill them with prejudice. They don't bite. :) You will also see them on top of the flowers and sometimes crawling up the stem. I've manually removed them every few days, and the problem is mostly resolved. I also found more details just now at: https://bygl.osu.edu/node/816 Good luck!

Your question about coneflowers overwintering was asked previously in houzz. HERE is the link to that question and the answers given. Unfortunately, I also have been unable to get coneflowers to come back for a second year. There are at least 6 species of the genus Althea, but I always picture SHRUB ALTHEA (Hibiscus syriacus) which grows 12 ft tall and nearly as wide. This althea tends to get pot-bound. If your water is hard it's also likely alkaline which can make your potting soil more alkaline over time. Shrub althea prefers a pH between 5.6 and 7.5. Although shrub althea needs 1 inch of water a week, it also does not like to be wet. Too much water causes lower leaves to yellow and die. What is good for the petunias may be killing the althea. Ideally, it should be planted in a prepared, well-drained bed with added peat and compost. Fertilize in the spring and fall, and use a fertilizer for acid-loving plants if your soil or water has a pH over 7.5. Water deeply, but allow the soil to dry between waterings.

I second Cathy's winter sowing suggestion. I've started many native wildflowers this way, using milk jugs. Echinacea purpurea doesn't require a cold stratification period, so you've got some time to put this together. You could try the Winter Sowing forum, or Trudi Davidoff's site for tips. Wintersowing is like having tiny cold frames, so the seedlings can get an earlier start with more even temperatures. You do have to keep an eye on them once temps start to rise, taking the tops off on warm days, and making sure the soil doesn't dry out. After the seedlings have hardened off, you can transplant them into the large (and hopefully deep) pots where they'll spend the summer. I also think cooper8828's advice would work although it's more risky if the weather is really roller-coasty in the spring. Also -- you might try posting this to the Perennials forum. It's a busy forum and plenty of Echinacea experience there.

Killing plants is all part of the process! Starting plants from seed is a great way to increase your plant options and can save you a lot of money too. Both echinacea and gaillardia are fairly easy to get going in regards to starting from seed.. So that’s good. Bad news is that if you bought common purple echinacea seed… they most likely won’t bloom the first year. Some of the newer seed varieties can bloom the first year if started early (indoors) to get a nice long season… though it won’t be a prolific bloom by any means. So if you are looking for a nice bloom show in pots.. Purchasing plants would be the way to go. If you don’t need the immediate show… you could do as you mentioned and get them into the pots early spring… make sure they don’t dry out.. And let nature do it’s thing. You will need to keep your eye on them though since they are in pots raised off the ground…. From drying out quickly… late freezing… etc. Another option is to scratch up a seed bed somewhere in your garden… drop the seeds down and lightly cover them... again let nature go to town. In the second year, you could transplant them out of the ground into pots if you want. OR…. you could try your hand at starting them right now indoors in seed trays and a simple bank of fluorescent shop lights. This method gives you more control of their conditions and you get a big head start on the season… and it keeps you busy in the winter! These could just then be transplanted to the pots or garden once the weather allows.