In NY you get to subtract the tax for the mulch when you pay the sales tax. Because you'll be paying the tax again on the bill to the customer. You need to track your business expenses. Like on Schedule C.
Equip and Supplies -separate out suplies for landscapping that are left with the customer
Maint and repairs
In NY plowing is taxable service.and it appears you have to pay tax on the gas twice. At the pump and in the contract.