Can they be planted in containers (flower pots) and what to do to winterise them. I live in Newfoundland Canada
Potentilla, often called shrubby cinquefoil, comes in different ultimate sizes but most will grow to be 3 ft (1 metre) tall and wide. It would need to be in a big container to hold a plant that size. There has to be enough soil so that hot or windy weather doesn't rapidly deplete the soil of moisture. If you are near the coast, your winters are moderate. The biggest risk is the soil drying out. Cold, windy weather robs plants of moisture even when they are dormant. That means you may need to water it if rain and snow are scarce. Choose your container wisely; it needs drainage holes and may crack if it is ceramic or terra cotta. A large foam-type container will provide some insulation. Wrapping the container in bubble wrap or tying bags of leaves around the container offers a degree of protection from frequent freeze and thaw cycles. Mulch the surface. It is going to be large, awkward and heavy so moving it to the garage or a sheltered (shaded and less windy) place will be difficult but is still advisable. Consider buying a plant stand with wheels. If you can't move it out of the wind, wrapping it in burlap will slow down moisture loss. Don't forget to add water if the soil seems dry. Where winters are harsher, cinquefoils suffer some tip die-back. I think your shrub will be OK if you don't let it dry out.