I have worked for one of the best Garden Designers in the UK. Also I researched and restored a Gertrude Jekyll garden, plus Chelsea flower show. If in this country you were to give a client a computer designed and printed design you would be laughed at. It must be done by hand and in our case watercolours are used.
The trouble is too many people use some software that shows them plants and what to grow. It does not work, you must know about Horticulture and the science of it, before you should use anything like that!
I had one boss who had a degree in Egyptology, who thought he could design. He was wrong, knowing about Egypt is one thing, knowing about plants and what the client wants is another.
Doing a seven year apprenticeship wher I did everything from hard landscaping to soft landscaping and everything in between that is the way I learnt!
What about pH of soils? I have seen so many expensive projects go sadly wrong. The wrong plants from a computer have been used. You must know your plants , soils, location, weather and look around the area. You will soon see what is growing and what does not. How many designers look at the native plants, as they soon tell you, what will survive and what will not!
So many designers around here, have no idea at all.
Regards from a cold England.
Neil.