Good morning and W elcome. Really need to break up the soil maybe with the tiller and amend with leaf mold or coarse compost. I would not put just sand unless it is very coarse grain. I grow iris and I till the cedar chip layer from the year before back into the soil before I plant. All wood needs to decay 1 to 2 years or it will poison the area for that planting season. But as far as fert, I don't use much more than bone meal, the nutrients are there.