Advice for overwintering this standard

Afternoon folks so I bought this standard daisy tree/ shrub in mid-summer from local garden centre for €10 and it gave us a second blossom of flowers. Now the season is ending and I would like to keep this over winter for next year so what advice or tips does anyone have?

I can store in my wooden garden shed.

 

I think they are Canary Marguerites (Argyranthemum frutescens subsp. canariae.)
If they are, they must be kept above 5C and won't survive frost, so may not survive in a shed.