Native wildflower meadows can be tricky things. There is more to it than many realise, certainly off the shelf mixes are rather hit and miss. If appropriate maintenance is available and your site is suitable then getting the seed mix right in the beginning will improve the long term performance of the meadow. These schemes are predominantly grasses and are predominantly perennial. Annuals and biennials might be included in certain situations. Even if your soil is rich there are some species that will work if management is put in place to prevent the big competitive natives taking over. Most urban sites have been altered beyond recognition so simply selecting plants 'native' to the area is not necessarily going to work. Plantforms can advise so get in touch to discuss your plans for a wildflower meadow. I can help you put together a mix that will suit your conditions and therefore do better in the long run, as well as setting up a suitable management regime.