The dollar weed is the one you have worry about first. There are three kinds of plants that grow in lawns. One is classified as grass or your target turf grass (these include common lawn grasses like turf type fescue, Kentucky bluegrass, St Augustine, hybrid bermuda, centipede, zoysia). Another is broadleaf weeds (clover, dichondra, pennywort, spurge, horse herb, black medic, creeping charlie, and others). The third category is grassy weeds which do not tame well (sedges (nutgrass and ), Johnson grass, crabgrass, common bermuda, barnyard grass, annual bluegrass, goose grass, and others). The broadleaf class of weeds are the bane of St Augustine lawns because they will easily shade out new growth. The St Aug will thin out fast and disappear in just a few months. With grassy weeds, the coarse blades of the St Aug usually shade them out. Fortunately there are different kinds of chemicals which kill the different kinds of plants. Broadleaf weeds are killed by the 2-4,d chemicals in Weed-B-Gone. Unfortunately St Aug is sensitive to 2-4,d also. Most plants are killed with atrazine but St Aug is not. I have not heard of penoxsulam, but then I don't pay much attention to herbicides. There is also Grass-B-Gone and Sedgehammer for the other weeds. Again, unfortunately, lawn grasses are killed by the Grass-B-gone product. The one good herbicide specialist is Sedgehammer. You might try the penoxsulam in a small spot as a test. Otherwise look for something with atrazine. Occasionally you see it as I described above. Your middle picture looks like crabgrass compared to St Aug, but it is the wrong time of year for crabgrass. I'm going with centipede. It looks like St Aug in many ways but it has pointy blades where St Aug has a boat-tailed shaped blade at the end. Simply taking care of the lawn with water and fertilizer will kill the centipede. Here is a picture of the two grasses. Then the prescription is to get a broadleaf weed killer that is safe for St Aug. My comment about this not being the time of year to kill weeds has to do with the plants not being in a fast growth state. You can try it. It could be your area is warm enough that everything is growing. I would fertilize with organic fertilizer, wait 3 full weeks, and then spray. You want the weeds to be growing and healthy before spraying. In the mean time raise your mower all the way up and weld it in place. There is never any reason to mow St Aug lower than full height. And keep the water off as much as you can.

The Weed B Gone Clover is not very effective to kill the weeds. I saw professional lawn care services sprayed week killer not only kills the weeds but also slows the grass growing. The lawn care services maintained lawn is still brown but my lawn has already changed to green. Do you know what commercial weeds killer the lawn care services use?

Where do you live? What kind of seed did you put down? Did you use a starter fertilizer? What is your watering program - how often and for how long? Lawn care is as easy as watering, mowing, and fertilizer. You're already overthinking it. This is the right time of year to seed a northern grass to minimize weed issues. Had you come here before seeding we would have suggested you water the bare soil daily to sprout any new weeds and then spray those out with RoundUp. Then you could seed without fear of getting weeds. But here we are. If you have broadleaf weeds in the old lawn, spot spray with Weed-B-Gone. If you have chickweed, clover, or oxalis, you'll need Weed-B-Gone Chickweed, Clover, and Oxalis killer. It's a different, stronger, product. It will not harm the old grass, but read the label for instruction around new grass. Forget about weed n feed products. They usually don't do what you expect them to do. The problem is when you need weed killer you don't need fertilizer and vice versa. If you want to fertilize now I would use an organic. You can use that at any time even on the day you fertilize with a chemical fertilizer. They do different things for the soil and plants. You can use the organic over the new and old lawn at the same time and at the same rate. Start with 10 pounds per 1,000 square feet. In 3 weeks you can reapply at the normal rate of 15-20 pounds per 1,000. But you do need to spot spray the weeds in the old lawn. Then around Thanksgiving or so you can fertilize with a high N fertilizer for the winter.

Weed and feed formulations are hugely inefficient in dealing with weeds and are also a major contributor to water pollution. And they can be problematic if you have small kids or pets using the lawn. You want to avoid them ;-) Based on what you describe growing in your lawn, a single weed killer will not work. Moss, ivy and nutsedge will require individualized treatment. Otherwise, most broadleaved lawn weeds and the crabgrass will be addressed by Bayer Advanced All-in-One Lawn Weed and Crabgrass killer. It comes in a ready to use spray as well as a concentrate and a hose end spray. But you may also want to look at pre-emergents for the crabgrass in spring. You will never be completely free of weeds.....it is just not the nature of a monoculture like turf grass. But developing a thick and healthy lawn will go a long way in keeping weeds to a minimum.