You don't. You just dig 'em out and buy new plants next year!

I like to propagate plants, but I haven't had any real success in over wintering surfinia. They are reasonably priced in the spring time anyway, but if you have some that you would like to save for next year you can grow them on as I have done.

Take cuttings just under a leaf node, and remove the lower leaves leaving about 2 inches of stem.

Dip the stem in a hormone rooting powder, and plant into small plant pots or trays containing a multi purpose compost.

Apparently surfinia is a registered trademark and propagation is technically illegal, however it is generally assumed that you can propagate plants for their own use.

Surfinias are produced from cuttings under copyright, and seeds can not be purchased commercially.

I have tried to grow surfinias from seeds that I took from my plants after they flowered, but they never came true and seemed to revert back to petunias.

Hope this helps?

Myron

I find some survive outside over winter, although my balcony is southfacing - I even had one that survived the winter before last - but all were killed last year. I haven't the room, but have often wondered if they were brought inside in the same way as pelargoniums whether they would grow just as well the following summer.