Olive tree in winter/fleece jacket
 

I was given an olive tree (Europaea) 4 or 5 years ago for mothers day, its now around 5 ft tall. I have it in a sheltered sunny (when we get sun) corner of my patio in a large pot. I have brought it indoors for winter each year but now it's getting too wide for the door so I will have to leave it outdoors.

The books tell me it's frost hardy to -5. I live in SW Scotland and we sometimes go below that so I've invested in a fleece jacket to protect it. It's like a large drawstring bag. I'm ubsure whether I tighten the drawstring round the trunk of the tree or the lip of the pot? Has anyone used these before?

We've had a few frosty spells already and the tree is still thriving without any extra attention. I'd appreciate any tips and advice.