FPF, has a good grasp on Brugmansias! Thank you for taking time to educate!
I read this, this morning but had a busy day so I'm just getting here.
AnnaZ, what is your goal for next year? What varieties do you have? Did you know some Brugmansia no matter what you do will be shrubs where as some are tree form. I have been hooked since 1995 when a friend brought me one to over winter due to his client didn't want the hassel. When he returned there was the mom plant and 6 babies.
You asked how far back you can cut. This year we put ours out right after our last frost date in the PNW and we got below freezing and snow! So we have been cutting back dead tops for the past month to get them to take off. Here are some photos to give you the ideas. First one is cutting back to 6 inches above the soil for the older brugs. If done right they should start shoots from the roots. But remember they need to grow, Y before they will bloom, maybe by fall if you push for growth until it Ys and then push for blooms with a bloom booster fertilizer.
I like the tree form so most of ours have been trained that way and a lot of trimming to keep them that way.
Sorry the Clematis are behind, so zoom in.
Here is our B. Frosty Pink and she is a shrub form.
I would recommend you allow them to just grow, fertilize and in the fall move them to bags and lay them on their side as recommended. While they are out of the pots, make sure you have good soil available to repot them. You know you can shave off some of the outer roots? Repot in good dirt. I would also take some of the newer limbs and root them. Do it in soil once the nubs form as it will make for a better plant.
Yes take them above the Ys as they should bloom for you the first year!
Some of us went to the publishers of the German version of the Brug Bible when we were at Yahoo to get the book published in English. I highly recommend the book called Brugmansia and Datura / Angel's Trumpet and Thorn Apples by Ulrike and Hans-Georg Preissel a Firefly Book. I have a first printing in English!
Scream if you need added information. Happy Growing!
There were two post before I could get my finished. AnnaZ, I dug up my west area to plant 128 varieties and you are right it was a huge pain to dig up so we went to the 5 gallon pot in a 5 gallon pickle bucket to move them easier with a appliance dolly. Save your back!!