Question
i would not mind trying an approach to rid my lawn of weeds by getting rid of chemical use. i have a large yard, and have been using chemicals to control most of my weeds. and to be honest, i don't have a huge problem because i do spray every spring, and then spot treat as needed during the summer. approx. how long does it take for the sugar to start working to keep weeds from growing?

Answer
David, David, David....

What is it you are spraying every spring to control weeds on your lawn?  Tsk, tsk!

But first things first.

There is absolutely no evidence whatsoever that sugar - ANY sugar in any form - will kill weeds or keep them from growing.

The term "sweeten the soil" means changing the pH.  Although there are some people who have been led to believe that Sucrose should be applied to their lawns as a means of weed control, it is not something any university lab or cooperative extension endorses, for reasons that seem obvious to me.

Much university research however has been conducted with respet to the very bad things that weedkiller does to you, your soil, your grass, your pets, your children, blah blah blah!  Thick, lush grass will crowd out most of your weeds.  You don't need chemicals for that.