I'll admit to not having done a ton of my own research on this topic so forgive me if there is a "duh, read this article" readily available.
The back part of my backyard is all landscaping that the previous owners had started. There is so much, we can't keep it up. So we want to take the middle section and turn it into yard, leaving the 2 corners landscaped with the trees and flowers, etc.
The middle section is all weeds right now because we just let it grow up and transplanted / removed all the good stuff. And we just keep it mowed. This fall, I'd really like to seed that section with matching grass but first, I need it de-weeded. What is the best way to go about that and is it something I can get started on now?
Also, before someone brings it up, I realize weeds aren't all bad. And single grass lawns aren't always a good thing (technically ours is 2 kinds of grass). But we live in a neighborhood with pretty strict lawn rules. So I'm forced into this a bit.
First, your lawn rules probably don't apply to your backyard, so you can do anything you want. But we can get you on a good path no matter what you want.
Next, the fall is often an excellent time to plant seeds.
Next-next: most weeds cannot tolerate regular lawn care - so they will go away and you don't really need to worry about it. Other people need to spend time and money on this because their regular lawn care is stupid.
All I've ever heard that grass called is "nutgrass" (because it will drive you nuts). I don't know the real name for it. And yes, I do not care for it because it looks completely out of place and sprouts up taller than the rest of my grass the day after I mow.
The only way I know to get rid of it in my existing lawn is to pull them out bunch by bunch, at least that is what I've been told because trying to kill it will just kill all the grass. However, since I have a large body of it where i don't care what dies, it might be nice to just rid myself of it if I can, in that area.
That is a Foxtail grass. Very common this time of the year. You can control it with pre and post emergent herbicides. Keep it mowed off and bag the clippings so you don't spread the seed all over the yard. It looks like you're on the edge of town; new construction, so I am guessing there are fields of this and every other invasive or native grass all around you. Seeds are going to blow in. Your best defense is getting a nice thick lawn and mowing at a height of 3 to 4 inches. You should still put down a pre-emergent herbicide for Crabgrass control but the other grassy weeds should not be that troublesome once the turf grass(Fescue) is going good.
I just wanted to add that there are organic methods of weed control to consider too, but again, emphasizing that a thick lawn maintained at a proper height is your best defense against weeds.
What someone called 'nutgrass', it grows faster than the good grass, is actually called nutsedge (not really a grass). It does no good to pull it up because you will never get the tubules out of the ground. You need to use a specific herbicide for nutsedge. There is a product called Sedgehammer that will do it. However, there are other products as well. Good luck.