contracts are essential, if the client doesn't want a contract, then you dont want that client.
You are a landscape contractor, contractors have contracts.
The bad thing about contracts is if they are written badly.
A contract can be as simple as something written stating "I will cut your grass, every time I do you will pay me $X.00" sign here.
You can get contract lawyers to help you write more intensive ones. You can get green industry consultants to help you. You could get me to help you.
Unless you find an angel, or do it yourself, It will probably cost you some money. But if so many successful companies are all using contracts, do you think it's worth paying to get them drawn up?
I would say, resoundingly, yes!