Expert: Viktoria Serafin - 7/8/2002

Question
I have a sunroom facing East.  The south facing windows look out into a highly shaded section (shaded by house next door and its tall arborvitae.  The sun does not penetrate.  I would like to plant something that would be green, about 6 feet tall.  My own arborvitae grew tall and lost all leaves up to about 10 feet (I think due to no sun penetrating.).  I would be happy with a perenial so that I would have green all summer. I don't care about the winter, as the sun room is not used then.  
So, what fast growing very leafy perenial could i use?
Thanks in advance for your advice.

Allan

Answer
Japanese knotweed.

No, no, no, just kidding!  This is one plant you definitely do not want.

Few perennials grow to that height.  You could grow Aconitum (Monkshood), Digitalis (Foxglove, biennial), Thalictrum (Meadow Rue) and Cimicifuga (Bugbane), and with lots of water and fertilizer they might reach that height but are more likely to be 4-5'.  Some of our native ferns grow fast and tall; Cinnamon and Ostrich ferns get quite tall, 4-5', as does Goldie's fern, but again you need to provide lots of water, especially to the first two.  Fertilizer is less important for ferns, and they can actually be damaged by excess.

You could also plant a Hydrangea Vine (Hydrangea anomala petiolaris) to climb up your Arborvitae.  It will not damage the tree.