Plants for North/West Facing Balcony

I don't know how big the balcony is, but we have found climbing hydrangea to be very useful in deep shade. Obviously, it climbs but is easy to control and will produce white flowers in spring/early summer and has dark green glossy leaves throughout the year. Primroses are also shade tolerant, and there are some lovely colours these days. Do advise your granddaughter to consider the weight of earth/water before doing anything! Happy gardening!

Thank you , the balcony is part of the building not sticking out
from the building,

Climbers are out, no wall, difficult to explain, the balcony is
the length of the living room / kitchen so all glass no wall.

If it gets some sun, there are petite versions of hydrangeas such as Anomala, which is white and would brighten up a dark space. Also a small pot so not too heavy. Some ferns would add interesting texture and a variety of green shades. Although they would have to be watered often.

My daughter used to grow veg In pots, plus geraniums, pansies and any bedding plants that she could find.