As you say, there are no hard and fast rules, but early June will be pushing it. My last frost date is April 15. Planting zinnias out any earlier than that would very likely be disastrous. Not only do you need to be frost free, but you need reasonably warm soil for them to thrive too. Typically, with my 4/15 plant date, zinnias are at their very best by the first week of July. You might have some cuttable ones by mid June if you plant enough of them. For the large flowered zinnias, I don't think there is any advantage to starting them inside early. The ones planted in good, well prepared, fertile ground will grow so fast that they quickly catch up to, and even pass the ones that were in pots.

The greenhouse I drove for a few years back grew thousands. By the fall they had reached perhaps 6 to 7 inches. The variation came in the branching rather than height. In the fall they were de-leafed and sorted from one bloom to five blooms and over and stored in coolers at 39 degrees Fahrenheit. Once they were returned to the warmth of the greenhouse after Christmas they grew fantastic. The five bloom and above reached at least 2 feet high by the shipping time. Today while walking I saw 2 Nikko Blue Hydrangeas in gallon pots out for the garbage man, I took those home in a hurry. They'll look just dandy next spring I hope.

Will try again with pictures. I dug down so that a brick could be put under the pipe and the pipe would be below the level of the sod. Outward to that I lay two bricks side by side against the fist brick to expand the floor. At the end of those two bricks I laid a couple of more bricks so the floor is about 3 bricks long. Starting at the pipe I laid a brick on each side of the pipe, creating a walls around the first brick, I laid two more bricks to create walls for the two floor bricks, so that the spill way expands as it gets further from the pipe. I just left the last bricks to lengthen the floor without walls. This is a work in progress and it has been so hot I have not mowed the yard in a week, but I think you can see what the intent is. As you can see in the second picture it is nearly invisible. and completely disappears from the house. (No comments on the quality of the grass. It is green and I have worked hard to get this to grow in the Carolina clay. ;-)

The dead branches were in the middle of the canopy. It kind of looked like the tree would split. When my arborist came over and saw it as he was giving me a bid on my trees, he said it may be dying IIRC. A few months later, a crew was there for two days taking down two trees. It must have been expensive. I've had trees half their size cut down for $500 decades ago. The trees were far enough from my property that only the paper-light top branches fell on the fence - no damage. The fence belongs to the neighbor who repaired the other damaged side of his fence promptly. I'm still not 100% sure that they won't trim the trees back to stump (which was carved out) but they are allowing the growth now. My concern is that soon it will be impractical for them to trim the trees without a professional team. I don't know if they consulted the arborist on the potential health of tree limbs that would grow back. The bigger tree had a seat carved out, turning it into a natural chair. So growth would be around the perimeter of the trunk. Does that jeopardize the structural integrity of fast regrowth? (I know almost nothing about trees, but I have seen maple and apple trees with multiple trunks and they seem strong as ever.) BTW this is my best neighbor - I need them to stay.