If you're willing to sacrifice this year's bloom it can be done now.

I've got a couple of noids just finished blooming and I'm digging them tomorrow for replanting.

Thanks, IrisGal. I guess I'll wait until July. :-)

alisande I would wait about a week after bloom. Things are tougher in Zone 4 than in Zone 9 or even Zone 6 or 7. The grass will keep them from growing as good as they could. Put Preen as soon as you plant them and then in the early spring. Grass seeds can germinate earlier than many weed seeds.

Mike G

If it's just lawn grass, I've been able to pull it out without digging up the irises - it just takes a little persistence and time. But quackgrass? Nope. I've got a section of my historic bed that I need to dig up this year. Argh. Unfortunately, quackgrass won't bat an eye at Preen - it's a perennial grass that spreads mainly via stolons/underground runners. Hitting it with herbicide (which I don't care to do) or grubbing it out by hand are about the only options.

Sometimes, if the ground is soft enough, even quackgrass will pull out. Spring is usually a very good time to try. I've been working on weeding all the things that tend to get grass in them because if I get it now, I won't have to do major excavation to get it out during the summer.

Anyhow, I'd start with fingers and an asparagus fork, and only move on to more major things after that doesn't work.

Gently remove iris and labels - spray grassy area with systemic Roundup (Glyphosate) when grass is actively growing. Wait four/five days and replant iris back into same bed. By that time Glyphosate has translocated to grass roots and is doing its job. You can even mow the area to remove grass on top. This makes iris replanting a little easier. This method requires minimal soil disruption, controls emerged weeds exceptionally well; including tough grasses with stolons like quackgrass, bromegrass, creeping red. It also discourages recruitment of new broadleaf weeds from seeds in the renovated space. Then keep bed edges clean from outside creepers crawling back into the bed from the edges. It won't be as pretty as a freshly tilled bed for a bit, but moisture is retained and iris have always done well for me in these renovations.
irisman646

Irisman, that sounds like an excellent plan, and one I never would have thought of.

Thanks, everyone!

Almost all my iris have grass growing in them. I cannot dig them all up; way too much work for me. There is some product something like "grass no more", that supposedly just kills the grass. Has anyone tried this and had success with it. I can barely see the iris plant among all the grass. Yes, I know.....looking for a fast fix.

Just go on line and buy some Grass Getter and a little crop oil and spray the darn stuff. Wont hurt the Iris or any other plant!! just kills GRASS. It works Awesome. I keep a bottle handy! one never knows when the grass will start taking over again.

Aquawise: what is "crop oil" and why do I need that along with the Grass Getting. Thanks for that suggestion. I really need help!

I would read the label carefully because irises are very very sensitive to herbicides. Your irises are going to be blooming soon, so now is a bad time to dig or spray. If you must spray, read the label and try to wait until the bloom is over, just another six weeks or so.
Renee

It is just a sticking agent. I have sprayed ever where in my garden with it and it only killed the grass. It only takes one ounce of spray and one ounce of oil in a gallon of water! A little goes a long ways. The grass was so bad that digging was not an option for me. there was Iris and primrose and daylilies and coneflowers, some ground covers. All were invaded with grasses, Lawn grass, Johnson grass, annual grasses. I was overwhelmed!!! So in desperation I tried this unknown spray. I waited and I thought its not working!! nothing is dying!!1 Then in about 14 days I see the grass is turning a funny color!! In another week it was all tan and dying.... That flower bed is now grass free. I had to spot spray a few places that I missed. All of the non grass plants never missed a beat. I was and am the happiest Grass Killer there is. I dont use chems unless I am at the end of my ability to get rid of something like bindweed and cheesy weeds. Then I get mean and do the spray thing. Never been sorry I did ether.

You can also paint it on the grass around the Iris is you don't feel right about spraying.

Aquawise:
Where do I get this crop oil, also called sticky spreader, also called a "surfactant". I can't locate it anywhere at Steins, Home Depot, Menards, or Lowes. I called the "grass getter" company and they were supposed to call me back, but never did. And I sure hope I don't have to buy a gallon of it on the internet and pay big shipping charge. I only need one ounce of it.

I am at my wits end. I need to get to this grass soon, its growing "like weeds" in my iris. There is no way I can pull out all the grass, I have way too many iris! Thanks in advance

Do you have a farm store near you? There is where you get the crop oil. You can buy it on line in a small amount. I will find and send you a link. This stuff save me a lot of work and the plants I sprayed it on never even knew they had been sprayed.

I bought one from Amazon a couple years ago and it does a great job. Here's a link to a search. The one I got was the Bonide Turbo, but I'm sure any of them would work.

Nate

Here is a link that might be useful: Amazon Sticker Spreader search

Update on Grass Getter:
It worked for my first group of iris, of course then the other weeds just took over. I used it a little later on another group of iris and it made their plant stems and flower stems kinda curley, but still bloomed well. Used it on my peonies, bleeding hearts and bluebells and I think it harmed them pretty much and got very deformed. I am hoping I didn't kill them.

I have successfully used Over The Top on bermuda grass and it didn't seem to hurt the iris at all.

I bought some "over the top" (concentrate), but can't figure out how much of it to use per gallon. The directions seem to be aimed for farmers with huge fields. I figure it must be something like a few drops or half a teaspoon. However, I am afraid to try it without more information.