thanks for adding me to your gardening with friends group

Msorganic if you are asking your questions because you are taking a horticultural course and are about to sit an exam I would suggest your go back to the course itself or google for the info. We are a large group of gardeners some professional, most not, your examiners will be looking for a specific answer in both cases.

If these are not questions for exams or test then I apologise but they certainly sound like it and we receive such every year...

Welcome, Msorganic!
I've already written an extensive rant on "exam pirates", and it doesn't bear repeating here. In precis, It goes like this:
If you want to actually do the job that you are training for--a prerequisite for getting paid--you will need to actually understand the course material. The best way of doing that is to search through the course material for the info that you need, and think about why and how it works. Cutting and pasting our answers may be less obvious as cheating to the instructor, but will not further understanding as well as the brain sweat involved in formulating your own answers.
If you run into material that you just don't understand, we will be happy to provide our own experience and/or a different perspective to further your understanding.
One of the things that makes us suspicious of your motives is the fact that you don't ask what kind of preparation you want to know about. Best read back a few sentences in the material to find that out first, then see what the following paragraph or two says.

Well said Tugb.!