When buying cascading petunias, plants produced by a gardening establishment should be selected, who has the right to reproduce or sell a given group of these plants. Why is it so important? Petunias often suffer from a dangerous viral disease, causing the deformation of shoots and a strong inhibition of flowering. It's hard to tell at the time of purchase, whether the plants are infected, because the virus only makes itself felt then, when petunias begin to bloom.
Warranty, that the seedlings are healthy, we only have then, when they come from specialized plants, which are licensed to produce cascade petunias and reproduce them in vitro (under sterile conditions, in the laboratory).
Manufacturers use different markings for their products. Some people place signs in their pots with information, where the petunia was produced, others use stickers on flower pots, they place large boards at points of sale.
Sometimes illegally produced seedlings appear on the market. It is against the law, moreover, plants can be sick.