Had the same problem. Two things that worked for me: 1. Get a weed hound or hog i forget the exact name. Take out as many as you can now and before they release seed. I did that for 4000 sq feet one spring. Hard work but great as it takes out the tap root and aerates the lawn and its kinda satisfying after a crappy day at work. 2. Weed b gon max. It works. Every weekend i would go out and spray any dandelions i saw (the ones i couldnt be bothered to take out using the weed hound), it takes a few weeks to work but keep at it and go back and respray every week. It kills it from the root. I kept mowing over the yellow flowers b4 they turned to seed and im guessing that helped as well. I did both of those one spring, and by the following spring you could count the number of dandelions i had on two hands. This year i have a few but i use the weed hound when im feeling fit and i spot spray every week until they die as well. Now under control With regards to the seeding. Im unfamiliar with the scotts steps, but i bought some pennington smart seed and threw it down in the fall after i killed off all the weeds in spring and it grew great by winter. Now i just fertilize every 6 weeks with scotts turfbuilder BUT never in summer and everything looks good. Good luck, im sure the experts here will give you some more detailed advice!

Probably is Ground Ivy, "Glechoma hederacea" and using any glyphosate product is overkill because they are very broad spectrum poisons that will kill everything they contact. Ground Ivy can be an indicator of a soil problem since they tend to want to grow. Generally Ground Ivy preferes a soil that is a bit too moist for most turf grasses and although they will grow in full sun they do prefer shady areas. Since these seed prolifically you most likely will not ever be rid of it.

Maifluer has the best solution given you don't want to hurt the clover. If you paint the centers of the dandelions with the herbicide, you should little or no damage to the clover, and if there is some, the clover should quickly spread to fill in any gaps. When painting it on, be careful not to let any drip from the brush onto the clover, and use a more concentrated solution than used in a hand sprayer. For example, if your directions say to mix 2 tablespoons of the weed killer per gallon of water, then mix it 50/50 or 40/60. When you put it on, you don't need to cover the entire plant, just dampen the center of the dandelion. Glyphosate will work well and leaves no soil residue that will hurt the clover. You can also use products containing 2,4-D or dicamba, although these can release vapors that may affect nearby clover (though it won't necessarily be killed). You may also need to make a couple repeat applications before completely killing the plants. Dandelions are particularly invasive where the lawn is thin, so be sure to correct the conditions causing thin areas to help prevent the dandelions from getting going in the first place.

To get a healthy lawn that will resist what we call "weeds" you need to start with the soil. The University of Illinois Cooperative Extension Service does not do soil testing but they can supply you with a list of labs that do. What you need to know from that soil test is soil pH and the amount of major nutrients, Phosphorus, Potash, Calcium, and Magnesium, and the balance of those and what you need to do to correct any deficiencies. Then dig in with these simple soil tests to see what else might need to be done. 1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top. 2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drainsâ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up. 3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart. 4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell. 5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy. It will take time to get to that healthy soil and then grow a good thick lawn that will make it difficult for the "weeds" to grow, and this will not prevent all "weeds" from growing, but the thicker the grass is the fewer of those unwanted plants there will be. Also mow the grass high, 3 maybe even 4 inches, because the more of the grass blade exposed to sunlight the more nutrients will manufactured to feed the roots which will then grow more grass.