How do I kill huge weed area in my lawn?

Here's an option to try. Good Luck!

https://www.everydaycheapskate.com/outdoors-and-garden/how-to-make-all-natural-weed-killer-super-easy-and-better-than-roundup/

Smother it! No sun = no grow. I used vinegar to kill off my old weedy lawn last spring, took 2 applications. Then dug all the old stuff out, prepared and amended the ground and spread seed.

Your zoysia grass should spread, although it may take a number of years. If your neighbors don't have it, make sure you install a solid barrier to prevent it's spread.

You can take plugs out of your existing zoysia lawn, and transplant them into the weedy area. A plug only needs to be about an inch or two wide. There are plug devices made for this purpose, or you can use a bulb planter or a knife to cut small plugs out of your zoysia. The area you cut the plugs from, just fill with a bit of topsoil, and the zoysia will fill it back in. I try to take it from obscure areas, like up against a garden bed, where the zoysia wants to spread into anyway. A one-inch plug I placed in a new spot took a few years, but it's spread to about 10' feet wide now.

Then, transplant the plugs into the area you want the zoysia to spread. You can just use the plug device to make the hole, or dig a small hole. Put them down a bit of distance from each other, and they will spread out and eventually meet up.

You can also just order zoysia plugs online or from a local nursery.

Hi Lizzy. I would cover the area with black fabric or plastic. Leave it for a few weeks and it should kill everything off.

Hello, Lizzy. Various online sites say to plant zoysia late spring to early summer. But I've also stuck a few plugs in at other times in summer, and they took--just kept them watered for a week or two until they took. If you can get the weeds killed off first, it would probably be helpful to the zoysia, so it has less competition. I bought a mat of zoysia plugs online, cut them up, then planted them and they did okay, but I had good luck also with cutting plugs from my already existing patch of zoysia, which a previous owner had planted on a slope. When we edge the garden beds, if we get some stray pieces of zoysia with roots, we just transplant them.

Where I live is not the best area for zoysia, since we get cold winters, but since it was already here, we live with it--it's a tenacious grass and would be difficult to eradicate. The zoysia section is brown from mid-November to about late March, though!