Every spring I have a patch of Clovers and Dandelions. Every Spring I put down a broad leave herbicide; they all die off. Then the following spring I do the same thing all over again. How can I end this cycle of them coming back?
Usually, having lots of weeds of any type is symptom of a lawn that is not thick and dense. If it is, it will block out most weeds on it's own. Still you will always have some, but they should be easily treated with some minimal herbicide applied via a tank sprayer. That minimizes the herbicide, which is better for the environment.
I'd start by analyzing what kind of grass you have and what shape it's in. Aerating, overseeding, proper fertilization, PH, etc could be appropriate steps to not only help keep the weeds out, but make it look better too.
I aerate every fall and over seed, I use Lesco Team Mates seed and my yard looks like a thick shag carpet. I have no other issues with the lawn other then what I said in the OP. Honestly, my yard looks better then EVERYONE else's in the neighborhood and most of them use a landscaper (Except for right now)
No one has mentioned "neighbors" yet as a contributing variable. If none of your nieghbors do anything to handle dandelions in their yards, then you'll be fighting them in your yard every year.
I was also wondering if the lawn is in such great shape, why is it that he's overseeding every Fall? That should only be required infrequently, it the lawn is thinning out from some problem. I'd also try backing off on the aeration. Aeration can be a good thing, but it does rip up the soil, which presents an opportunity for weeds to enter.
I'm not really sure why I over seed every year.. I guess I thought it was the thing to do to keep your lawn looking nice every year. I've been looking where the clovers grow, I now see that I need to thicken it up some more.
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