Having read some of the comments about gardeners and what they charge.
I myself since 2000, been self-employed as a gardener, and have
charged by the hour.
But have been losing out on travel time,etc etc

You might sit down and write up your costs and the prices you charge,
both so you can make a good estimate and also show prospective clients
that the work *isn't* priced on the same basis as a 40-hr job in a
shop. And don't think charging for the job instead of an hourly rate
is fool-proof. In that case, you must be *very* careful about
estimates and get everything in writing. You could estimate 2hrs
(actual) work for a task, base your charge on that, and find that the
client wanted to follow you around and chat, or you had to spend 30
minutes finding someone to take charge of a dog. *Every* job has
overhead. :-)

You have to be very careful if charging by the job. Put your estimate
in writing and make sure you specify clearly what is included. My
experience is that I often get asked "while you are here can you just
do this extra bit of pruning/ weeding etc? " Before you realise it you
are doing a lot more than initially agreed. Unless I can clearly
define exactly what is to be done I always try to charge by the hour.

The rate you can charge depends also on the competition. In my area
there used to be some recently retired people around who did some
gardening to supplement their pensions. Their rates were cheap because
they paid no tax or insurance. To make matters worse most were also
competent gardeners, some had worked in the local Parks Dept when they
employed skilled staff.

David