Thoughts on hiring experienced workers ($$$), or newbies ($) for a new/small business

I am a small fine gardening business and am seeing the  need to hire someone to take over the lions share of my day to day position out in the field. I have a part time person who works with me 2 days/week and they came to me knowing very little of the work. I don't trust them to go to sites without me over and over because their knowledge and skills are not there yet. 

Question is: do I spend more money and hire a knowledgeable person with extensive horticultural knowledge that I would have more confidence in (but also a higher risk of them leaving to go work on their own as many of us do in this biz), or do I find another newbie and try to give that a go again? 

Thank you! The goal is to free up my time to do more business and design work in the office rather than be out in the field every day and do office work in the evenings.