How long can you freeze plant material?

If i take stems and leaves and put them in the freezer for making hash later, how long do they last ?

longer than you should ever need

As has been stated, you can freeze it for as long as you like. Make sure it is fully dried/cured before you freeze it so the cells don't rupture.

You can freeze it, as long as you want, but freezing does degrade THC slowly into CBN. IME a few weeks wouldn't hurt trimmings and stems that much more than freezing it a day, but it would be noticeable to a dab expert.

I'm making hash from trim I accumulated in 2011 and 2012. Material has been in freezer for 3 to 4 years. I just germinated some mystery seeds that have been in my 'fridge for 2-3 years. About 50% of them popped up.

BigSteve.