Posted: 08/10/2014 at 09:44
I have done lots of penstemon cuttings, never used a bag.
I wonder now if its a bit late to leave them in your greenhouse, if they were already rooted it would be ok, can you put them on a unheated windowsill indoors, out of the sun.
You could try some in a little glass of water, I did my michaelmas daisys like that and they all root.
When you do take them, just pinch out the growing tips on the cuttings then you wont get a tree.
Keep them only just damp through the winter or they will rot.
You will soon get the hang of taking cuttings and find whats best for your area, its really satisfying to say that you have grown that plant rather than just going out to buy it when someone else has grown it.
I am totally hooked on self propagation and after you sed your successes, so will you be. Good luck.