I agree that those two books are more ‘folksy’ stuff, but there are a few tips to pick up.
Do you have a lot of squirrels and chipmunks in the area? That could be your Sunflower issue because they will dig up the seeds to eat and nip off the seedlings before you can say, ‘Bob’s Your Uncle!’
They seem to leave established plants alone, so I generally start a bunch of varieties in flats and put them in the garden when they have four leaves (two seed leaves, two adult leaves). That has worked for me.
It’s always something! ;)
We used to have lots of the cute little brown squirrels here, but some idiot introduced the Eastern Grey, and now the indigenous ones are being displaced. There are a few greys here, but only perhaps a half dozen in the immediate area (square mile or so).