Can we prune magnolia grandiflora in winter?

Hi Augusta,
I am not in your part of the world, but you need to cut back hard, some of the branches and tie in others to give light to the other residents. I would say you are similar to us, coming up to winter and if I was cutting back this evergreen shrub it would be at this time of year.

NO!!! Magnolias should not be pruned when there is a threat of frost. Wait until spring before cutting it

Yes Andrew, ideally in the summer, but this tree needs to be cut back to allow light into their neighbours windows.
I have had to do it on a very large Magnolia in November growing against a house and putting in a cable to support it after wind damage.

I know of a Magnolia Grandifora which was pruned hard and which took 6 years to get back to a height where it flowered again.

With plants like this, magnolia, azalea, camelia and rhodedendrons, wait until it has flowered then prune before the plant uses its energy to produce more leaf growth which they usually do after flowering. A Magnolia Grandiflora should never drop its leaves as it is evergreen. It may sulk for a while after pruning as magnolias tend to do this when moved or pruned and you may miss a couple of seasons flowering, but it will be worth it for the neighbours. Don't prune now whilst there is a threat of frost it could be fatal.

Evergreen yes, but they lose leaves all the year round and often flower for a long period of time

Yes, I should have said it isn't deciduous and will drop a small amount of leaves like a human with hair. That is what I meant by 'shouldn't drop its leaves'
We have to bear in mind this site applies to different members from different climate zones and they may prune at different times to people in the UK depending on the season and temperatures, the shrubs may even flower at different times than the UK. Vancouver being Zone 5, this would be similar to the climate in the UK and I would certainly bear this in mind. I'm sure if you explain that you will give the tree a good prune after it has flowered, or in the Spring, I'm sure they will understand.

In my own experience growing this Magnolia in the Pacific Northwest, I find that it flowers sporadically throughout the growing season so I would not worry about waiting for it to finish flowering to prune it. I would recommend this for your situation: Decide how much you think you want to prune off, (remember try and be conservative as pruning severely will not be good for the tree and will look terrible) then take one third of this amount off now and then wait until late spring to do the other two thirds.
If there is not too much pressure from residents then do all the pruning in late spring.
Do not expect it to flower in copious amounts in 09'.

Cheers,

Podocarp