Don't think of your CV as a list of your experience or what you have archived but more of a presentation of what you will bring to the position that is being offered.
Look at the details of the advertised position and try and match your skills in an ordered fashion, matching your skills with the employers requirements - The prospects website offers good advice on writing your CV.
One of the things, as an employer that I would instantly look for is loyalty to previous employers.
Having several previous jobs or even a career change will certainly not be held against you but a regular turnover of positions will be regarded as a big black mark.
Bearing in mind that gardening and landscaping is a seasonal craft, I would pay attention to dates or more specifically, timings of career changes - believe it or not, there are 'fair weather' gardeners who would switch to inside jobs in the winter.
I have had an unfortunate experience of taking on a working manager of our garden maintenance division who had been in education for the seven years previously. On paper, his qualifications in horticulture had made him an ideal candidate.
The seven years should have rang a warning bell because as it turned out, practical and hands on skills were non existent.
I realise that every one must start somewhere but serial education and lack of gardening experience is too one sided for an employer to take a chance. Try to get experience early on and clearly mark it on your CV.