My yard is overrun with weeds. Went to Menards and asked what I should use. I was directed to Roundup and told to spray it everywhere.

I'm not a landscaper, but even I know that's the worst thing to do.

Is Preen a good brand? What should I look for?

Not that simple.
http://www.randylemmon.com/lawns/fertilize.html

For short term broadleaf anything from Walmart will work. For long term you have to follow a schedule.

I think OP is way up north (not Texas). Randy Lemmon will not be the program to follow.

Go to Neil Sperry's site and he has great recommendations for all areas of Texas. His advice is simple and it works. Stay away from Randy Lemmons recommendations unless you have lots of money to burn. He sells himself and his show to the highest bidder. You can also call Neil on Sunday mornings on WBAP 820 8am to 10am and he will talk to you live.

Here is link

http://neilsperry.com/

OP is in Montana

Histag, what kind of grass do you have? 2,4-D is usually a good option that is cheap. Just make sure you add a surfactant to it. A little bit of dish soap will usually do the trick.

Tried 2-4-D. Didn't kill anything umfortunately. I believe we have a blue mix, not sure though. Mainly trying to get rid of the weeds so we can assess the grass and decide if we.can just seed in, or if we should go nuclear and start over.

Yes, I am in Eastern Montana.

Did you add a surfactant to it? The stuff at the store doesn't have one in it. They really should add one in there because 99% of people don't think about it.

If you did and it didn't work try some trimec

I may try that if I can find it. It was ridiculously hard to find 2-4D

Domyownpestcontrol.com

Free shipping.

I will look into that. I know the state has restrictions on what private individuals can and cannot buy.

Any opinions on Preen? We decided to try that. (The stuff you use in a spreader, not liquid)

What was the active ingredient on the bag?

Preen has a few products now where their only product used to be a preemergence product only.

2-4-d
Propionic acid
Dicambia

Those are the 3 listed as active ingredients. We did not get the preemergent

Those AI's should work on a wide spectrum. If you haven't applied yet, I would do it in the morning when there's a little dew on the weeds. Will help to get the product to stick to them and then solubilize on their leaves. For sure follow the directions the packaging for best results. You want actively growing weeds for auxin-type herbicides. If rainfall has been lacking or overly hot/cold conditions there's a chance of poor control.

I'm not a fan of ganulars for postemergence applications as they can be difficult to get good results (lack of coverage compared to liquid).

We put it down today. We watered heavily last night (part of instructions), and put it down while it was still slightly damp.

We will see how this does. We have pretty much tried different things every year and have d3cided if this doesn't work, we will likely go the nuclear option

It seems to have killed my grass (or at least yellowed it), and the weeds are still thriving