Grass along ditch is probably winter rye. Used in Ag to break up compaction. You have identified its problem-killing or control of it.
The other sounds like sedge grass which is beyond nasty and very easy to spread.
Preem is a pre emergent herbicide. I keeps seeds from germinating. It does not kill anything. It does not work on some kinds of weeds-more for the grass like weeds.@ducks4you, I wonder if Preen will kill off the little bulblets as they sprout. It is a good idea, for the seeds that nutshedge put out, but apparently this particular weed spreads by bulblets, runners and seeds. What fun!
We have used the powder you mix with water and spray. It wasn't a miracle product, but did seem to stunt the growth a bit. It's kind of expensive, though.
@flowerbug do you think that grass could be Johnson Grass? That description of the roots sounds like it could be.
There are a few broadleaf weeds that preen does not prevent but it does a pretty good job. I would never use it on vegetables. There is an organic preen, which is made from corn gluten. I have used that on onions as they are difficult to keep weeded. Again that does not prevent certain broadleaf weeds but it does help. My big problem is an invasive grass that spreads through underground rhizomes.I have been weeding a flower bed all morning. No matter how well it is weeded a little bit of the invader is left behind to cause me to go back to weeding. It was perfect last fall, it is now not too bad so I am working at it so it does not get out of hand. I will lime, fertilize, use cardboard if I can get more, mulch heavily with leaves and then Preem. It is work but, weeding is good for the restless mind and a joy...WHEN IT IS DONE!Also, read about how people here like @catjac have been using cardboard and layered paper (including newspaper) to mulch right next to your plants. Preen is a herbicide specifically designed to kill ALL seeds for about 3 months straight, then you reapply as needed.
If you HEAVILY mulch around your plants mid season you can keep most of the weeds from sprouting then and THAT is when you will damage vegetables giving your their fruit. I did that by mowing/mulching burdock that hadn't gone to seed (1st year burdock) and spreading it 3-4 inches thick around my peppers AFTER using Preen several inches out from their stems. I pretty much had few to no weeds sprout up bc they had no sun. Btw, after 3 months the mulch had turned into dirt, still very few weeds, and those could be easily pulled out.
Do NOT use any kind of wood mulch besides pine bc some can be toxic, like walnut, and then you will kill pretty much everything in the bed.
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Do NOT use any kind of wood mulch besides pine bc some can be toxic, like walnut, and then you will kill pretty much everything in the bed.
Well you've never seen mine. But it's tiny so I can keep on top of it. If fact, I get excited when I see a blade of grass!I must be lazy as I’ve never seen a weed free garden. Grass is Best killed with a herbicide that will go nameless......