Creating a wildflower meadow
I'm new to this site but would love to ask more experienced gardeners for some advice. We would like to create a wildflower meadow in our field in an area approx 5 metres by 15 metres. The main issue we have is that our house is on the site of an old school and the area of field that we own is where the tennis courts were built. The tarmac for the courts has never been removed, and over the past 35 years a thin layer of soil (perhaps 5 cm) with accompanying moss and grass has settled on top of the tarmac. I am aware that meadow plants thrive on poor soil, but will this be too poor or shallow for any wildflowers to grow in? Should we add some soil to the area? Or should we dig up the tarmac? The tarmac itself is so old and soft it could be dug up easily, but there is lots of rubble underneath which is trickier to remove. Also, this area is underneath one large crack willow tree and a few smaller trees- would this also be a problem. Thanks in advance for any tips or advice!