There ARE lawn weed killers approved for use in Canada (and specifically, Ontario). Look for Scott's 'Eco Sense Weed-B-Gon. And many find a quick trip across the border very useful as well :-)

Your only other option is manual removal. You can also try vinegar (pick a good sunny day) but that is a nonspecific type of herbicide and will also kill off any turf grass it manages to come into contact with. And is not all that effective against deep rooted perennial weeds like dandelion and burdock, as it only kills off the foliage by dessication.

Gardengal. could you look at the thread Time to Fix the Lawn? They're in Washington and want advice. Crushedpurple, sorry to interrupt your thread.

"If you pull up the weeds, you will only expose more weed seeds to grow."

Argh so I wasted all my efforts on pulling out weeds thus far :(

So if stop pulling out weeds for now and wait until August to do a thorough manual de-weeding and the use an overseeder to plant grass seed in the fall how effective would I be in curbing weeds for next spring? Is using weed killer necessary? If yes, what's the best kind and when's the best time of year to apply it?

How about throwing down some super fast germinating annual rye? In Ontario I'm guessing the summers aren't too brutal and the grass might make it through the summer. I'm assuming your lawn is sparse and this might be a cheap way to increase the density until you are ready to do a proper reseeding in the fall.

I'm thinking about ordering this: https://www.amazon.com/gp/product/B001OENXRI/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Anyone have experience with it? Just wondering if it's good for forget-me-not too. If not, I want to get rid of those before they self-seed, when is the best time?

I've accepted forget-me-nots in my garden. They're wildflowers to me, not weeds...just very, very, very, very exuberant wildflowers. I've encouraged them to grow in certain places, and they are very pretty to look at. As long as they don't bother the other plants, I let them be. I have lost the forget-me-nots war, and graciously accepted defeat.

I like them myself ...but at the same time don't want them to take over. I realize that I probably can't ever get rid of them....I have also noticed at least 2 different types of white flowering plants/weeds/wildflowers

I'm in Ontario too so I know that finding herbicides can be a challenge. Having said that if you take the time to search the web you can find almost all the herbicides you see talked about on this site from places in the USA that will ship to Canada. If you don't want to go the route of selective herbicides why not just round-up the hole lawn and do a full reno? Although round-up concentrate isn't sold at the big box stores, you can easily get the pre mixed round-up in spray bottles. Spray the area and start again. Also be careful what seed you buy if you go that route. I've used scotts seed for years and although it's not bad there can be a fair amount of grassy weeds in the mix. Poa triv/annua, Quackgrass can be in a bag of scotts seed. I'm going to be doing a full bewitched KBG reno this year as i'm about done with overseeding my nomix lawn every year.

I feel kind of bad for doing this as I know there's a reason for the ban but I went ahead and purchased 2 bottles of this stuff - supposedly it's safer for the environment than the other stuff: https://www.amazon.com/Spectracide-Crabgrass-Killer-Concentrate-HG-95703/dp/B001OENXRI

I'm hoping that if I'm able to kill off the existing weeds and prevent any new growth for this year, that overseeding will choke most of the weeds for next year so I won't have to use anything.

My only concern is that if I do it now, I'll need to remove all the dead weeds which will leave huge patches (I have a huge section of crab grass), which will be unsightly considering that I'm not overseeding until Sep.