All those are good suggestions. If you want to get this back on track, it is a little too late for most of the US to use chemical fertilizers. Now would be a good time to learn more about the modern organic approach to lawn care. You can use a grain type fertilizer any day of the year, in almost any amount, with no fear of hurting anything. The only drawback is it takes 3 weeks to see the improvement. With your lawn the improvement will be as delicate as your supposed stripes you have now. Yes, I do see them, but jeeze Louise, talk about subtle! This is what can happen to your lawn on a super organic regimen - meaning where most lawn nuts would apply 100 pounds of grain fertilizer per 1,000 square feet over the course of an entire season, this guy applied 1,800 pounds during the season. He was looking for the limit where enough is too much, but he never found it. Here's his lawn in July of 2010. Note the subtle difference between his lawn and his neighbor's lawns. The lawn is a mix of elite Kentucky bluegrasses. He was watering deeply once a week, mowing at the highest setting once a week, and fertilizing with 50 pounds per 1,000 of soybean meal and Milorganite ONCE A WEEK. If you want to do that, you're welcome. But all you really need is 20 pounds per 1,000 of alfalfa pellets (rabbit chow) once every other month. But if you want unmistakable results, you can apply more often. The first time you apply it will take 3 full weeks to see the improvement. After that it just remains deep green like that all the time unless you miss a drop. Back to your lawn: In that condition it would be the best lawn on my block. Since you seem to be looking for perfection, let's ask some questions. Where do you live? What kind of grass is that? What is your watering regimen? How often and how much do you apply? How high/low do you mow and how often? How often do you fertilize and what do you use? Otherwise the lawn looks great.

Whether to use grass clippings from turf that was covered with a "weed and feed" or not depends on when that was done. As a general rule you can use those grass clippings in compost after a couple of weeks, dependinig on how much water has been applied since the application. Grass clippings that are mulch mowed back into the turf are a far better use of those clipping than picking them up and putting them someplace else, even a compost pile, unless so much synthetic fertilizer has been dumped on that soil that the Soil Food Web no longer exists. Leaves can have a C:N ratio of anywhere from 40:1 to 80:1 so a lot of extra N is not very often needed, but moisture is.

The "feed" part won't hurt anything, it's just fertilizer. But the "weed" part is a problem. Check the package and see what it is. If it's a pre-emergent, like Preen, you're probably OK. If it's a weed killer, like Round Up, then you could have trouble. Water, water, water! You want to try and dilute it as much as possible and get it to dissipate down through the soil away from the roots. You may see some peculiar or distorted growth as a result too but it should go away with some time.

I've been on an organic program since 2002 and am not aware of an organic weed n feed. Furthermore had you asked about a chemical weed n feed, I would have discouraged you from using it. It's one of those products that sounds too good to be true. The problem with weed n feed products is the timing is off in two different time frames. In the big picture you need to kill weeds in April but the grass does not need its first fertilizer app until late May. On the small time frame, weeds die best when the are well fertilized. When you apply wnf, the herbicide tries to go to work right away but the weeds have not received the benefit of the fertilizer yet. If you want to apply a fertilizer, it's best to use a straight fertilizer. If you want to apply a herbicide, it's best to use a straight herbicide. Liquid herbicides are meant to be sprayed on the leaves of the weed and not applied as a soil drench. If you lightly mist the dandelions with something like Weed b Gon, you should not bother the soil microbes or worms.