Our Residents Association is looking to plant a load of flowers on a
roadside embankment (approx 100mtrs long) to brighten it up a bit.

The embankment soil isn't fantastic and it faces eastwards.

We have already planted some daffodils and primrose which are naturalising
nicely.

Can you recommend any other naturalising flowers which will help us cover
the embankment with a sea of colour during the growing season? And also any
bulk seed/bulb suppliers.