Nj, if I've got it right, you are planning a higher-6" to 8"-mowing just for this coming growing season, and perhaps the one following, to interupt weed seed cycles. IF that is so, it is indeed a normal part of meadow establishment. I guess to answer your question, the only one that will flower despite this early-stage mowing is what you've already identified-Rudbeckia hirta. Not saying none of these others won't also, just that in my experience R. hirta is one that can be dependably counted on to flower despite these early-stage mowings. The thing I'm not getting though is the presence of the tree and shrub species within this mix. Not at all saying I don't like them, just I don't see how you can have a meadow in which woody plants are purposely part of the mix. Are you intending to have these woody species around the perimeter? That could work. Then, once you've got your meadow up and running, fire is the best tool, but timely mowing can and often does suffice, depending on other circumstances. Or, one can purposely let the meadow undergo natural succession. That's what happens in nature, in areas of the country like yours and mine which were formerly primarily forested. Meadows would indeed exist, but as a seral stage following a disturbance of some kind. When we create these things, we have to bring the disturbance to them if we want it to remain as meadow, prairie, etc. Quite an extensive plant list BTW. +oM

Do you know when your mowing will take place? I like to have things mown in the late fall or late winter (although this isn't the best thing for wildlife) and then not mow again until July or so. This timing isn't great for fall blooming native plants, but keeps the grasses under control and looks neater imo. I'm trying to avoid having goldenrod take over. Most of the later plants like bluestems and asters come up again and bloom normally, just a bit later and shorter.

It depends on your site and what your ultimate goal is for the area. Eliminating existing competition from whatever is growing there now will most often give you the best results if you want to promote a dense planting of native wildflowers and grasses. Think about this way. Whatever is growing there now has already proven its ability to outcompeted native vegetation. That's why those species are flourishing there instead of native plants. If on the other hand, you have a significant amount of native species, then it might be reasonable to work with what you have. It is also possible that you may be satisfied with not going totally native and to just have a meadow look with the option of introducing additional species to add color and interest; albeit, hoping that those introduced species can coexist with the existing vegetation. The advantage of going the later route is that it will be a lot less work. You have to check with local weed laws to see if any of the above options are viable.

I am 3 yrs in to a similar project to what you plan to do. Establishing a tallgrass prairie (1/2 -2/3 of a acre) on our property in the country. We have a heavy deer population in our area as we live next to a large block of land that does not allow hunting. I maintain firebreaks through, and around, the entire area. This way I can kill off and plant one small area at a time. Also, when burning, I can burn one or two areas without burning the entire prairie. One thing I am doing differently is actually planting young plants. I winter sow them in containers over the winter to stratify the seed and then plant them out when they are big enough over the course of the summer and fall. Big job, over 1000 plants so far, but that's another story. Back to the deer. From my experience, with over 100 species of forbs and grasses native to the midwest, the deer are a BIG problem. They will not touch any of the sedges or grasses, but, they will eat just about any new growth on forbs...especially this time of year (in the spring). Here, there are certain plants they will devour at any stage of growth - asters, oenothera, and all of the native legumes. I have several dozen small cages I've made from 2' and 3' fencing and I put these over small seedlings as I plant them out - I keep them in place with long landscape staples. After they become established I remove the cages and use them on new plantings. The one thing I've not heard anyone talk about is where they walk. I have lost more plants to them crushing small plants than I have to plants they have browsed too heavily. This could be a problem in your case, not planting seedlings and sowing seed? Make sure to plant at least 50% grasses, not only will deer leave these alone, but they will be the backbone of your project. Not gonna lie, it's going to be tougher than you think it will - woody vegetation, weeds, deer, weather, etc. - but, it is very rewarding. Amazing, the variety of wildlife we see enjoying our tallgrass prairie area.