Annual wildflowers on thin soil?

Hi All,
I dug up the paving stones in my south facing front garden in the hope of sowing some annual wildflowers until I had more time/ideas.
Underneath the slabs I found a mixture of small pebbles/sand on top of membrane.
Under the membrane I found a layer of larger pebbles and concrete
The concrete has a large hole in the middle and is in disrepair. I left the layers I disturbed.
If I mixed up the gravel/sand mixture with some clay soil from the back garden - would I be able to still grow the annual wildflowers?
I haven’t detected any puddles after rain and the pebble/sand mixture is about 4-5 cm thick and just a bit damp.
The annual wildflowers are:
Californian Poppy, Common Corncockle, Moroccan Toadflax, Wild Chamomile.
It’s probably a silly idea but I would like to sow something there now I’ve got rid of the paving stones and it’s open to every weed in the world!
Thank you
Ax
I dug up the paving stones in my south facing front garden in the hope of sowing some annual wildflowers until I had more time/ideas.
Underneath the slabs I found a mixture of small pebbles/sand on top of membrane.
Under the membrane I found a layer of larger pebbles and concrete

The concrete has a large hole in the middle and is in disrepair. I left the layers I disturbed.
If I mixed up the gravel/sand mixture with some clay soil from the back garden - would I be able to still grow the annual wildflowers?
I haven’t detected any puddles after rain and the pebble/sand mixture is about 4-5 cm thick and just a bit damp.
The annual wildflowers are:
Californian Poppy, Common Corncockle, Moroccan Toadflax, Wild Chamomile.
It’s probably a silly idea but I would like to sow something there now I’ve got rid of the paving stones and it’s open to every weed in the world!
Thank you
Ax
0
Posts
In the sticks near Peterborough
I was also thinking Common Knapweed.
I was thinking mixing rich clay with the small stone/sand mixture is what clay soil needs and it has been covered up for years with the paving. Annual wildflowers could grow on this mixture and deplete it for perennial wild flower planting in autumn?
My only worry was that approx 8cm might be too shalllow for the annuals and instead I create a super mix for weeds.
It’s super sunny and the shallow soil might get dry very quickly.
We shall see and I guess actually trying to grow something will teach me more about the plants.
Thanks Ax
In the sticks near Peterborough
patchy but I can build on it Year after year
Thank you for the encouragement and inspiration that I get on the forum x
not that we want thanks as such, it’s just good manners.