Help on new sod: Two questions

slclouseMarch 10, 2013

I moved from Iowa to OK 4 years ago and recently my bride and I built a new home. Sod was laid with Bermuda, which obviously we didn't have in Iowa. The sod was laid in October and I have watered it all winter. I put down a winter fertilizer, but my sod is now full of a purple flowered weed and clumps of green grass. Also, there are lots of spots where there appear to be sink-holes in the lawn.

Question 1: Will it hurt the sod to spray the weeds with a weed killer?

Question2: How do I fix these OK sink-holes and get the sod more level?

Thank you for helping this new Oklahoman learn to grow in Red Clay.


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I cant say much about you lawn. But in the past when I wanted Bermuda only I would spray MSMA in warm weather (90) or above. I always tried to be gentle with a new lawn and go light on any chemical.

The sink holes, it your lawn is like mine you will just have to work with. I have wild critters that like to see that my lawn is not smooth. Larger areas I place soil on top of the grass and spread it with the back side of a rake. You can do this in thin layers and just barely notice the grass not showing above the soil.

When I was working on a new lawn I would start a flower bed or garden in the back (out of sight). I would dig soil or buy soil to use the stash in the back as my" Soil Bank". After I got the front lawn like I wanted it I would then fix the back as I wanted it. After the lawn was established I would us MSMA and a pre emergent to control the annuals. This was many years ago and there may be much better chemical to use now.

If you have moles and gophers you will get the chance to repair your lawn often.


    Bookmark   March 10, 2013 at 2:07PM
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Okiedawn OK Zone 7

Slclouse, Welcome to the forum.

The purple flowered weed likely is henbit. The green grass is one of the cool-season winter grasses. If it is very fine bladed it likely is poa annua. If it is a wider bladed and taller grass, it might be winter rye grass. I've been pulling up clumps of poa annua and winter rye grasss out of my garden for the last couple of weeks. I leave the henbit alone for the most part because the butterflies love it so, but I'm in a very rural area where such weeds are tolerated more than they are in town.

The standard recommendation for killing winter weeds in bermuda grass in winter is that you can spray them with a contact herbicide like glyphosate in January and February when the bermuda grass is completely dormant. Whether you'd be able to do that in March, even this early in March, is sort of iffy. It would depend on whether or not your bermuda grass is absolutely, totally and completely fully dormant and all tan/wheat colored or if it has begun to green up.

You'll have to look closely at your bermuda sod and see if you would feel comfortable spot treating the weedy spots with a glyphosate this late in March or not. Would I do it? Yes, but then I hate bermuda grass because it is highly invasive in garden beds, so I wouldn't care if it all died. I also am far enough south that we do have bermuda that is greening up so if I loved my bermuda grass lawn, I probably wouldn't spray Round-up on the weeds this late in winter. Since you're a couple hundred miles further north than I am, your bermuda may not be greening up yet. Look closely at the stolons at the ground level and see if you see green. My blades of bermuda grass for the most part are not green, but my stolons are.

Otherwise, you could use a contact herbicide that is labeled for broadleaf control in turf, following label directions. I don't know what the standard treatment is for poa annua because I garden organically for the most part and just don't worry about it. It used to be, in my pre-organic days, that they recommended an arsenical like MSMA or DSMA for many of the weedy grasses, but I haven't stayed current on synthetic herbicides since I switched to organic growing and don't even know if those still are available. A grassy weedkiller would take care of the cool-season grasses,but not the broadleafed weeds. A glyphosate would take care of both.

In future years, a pre-emergent herbicide applied in the fall before winter weeds germinate would prevent these weeds from sprouting in the first place.

Now that I've given you the correct answer, I'll give you the anecdotal one. Bermuda is fairly hard to kill, especially when it still is mostly dormant. I find it hard to kill bermuda grass with Round-up even when I am attempting to kill it. It will brown out and look like it is dying, and then a couple of weeks later it will show signs of recovery...and that is if I spray it during the warm season when it obviously is green. If I had the weeds you're seeing and a weed-free lawn was important to me, I likely would spot treat with a glyphosate today or tomorrow while the temps are still cool. A week or two from now with high temps in the 70s, I wouldn't do it. I'd be too afraid it would stunt the bermuda or even kill it in spots. You should be aware that spraying glyphosate on a bermuda lawn is one of those "do it at your own risk" things, and if I was doing it, I wouldn't spray any part of the lawn that didn't have weeds---I'd just spray the weedy spots.

I wish you'd asked this question back in February when the answer would have been more clear cut because the grass was definitely still dormant then. That's why it is recommended to spray bermuda grass with a glyphosate for weed control only during full dormancy in January and February.

As for the sinkholes, can you describe them a little better? How often do they occur and what size is each sink hole? If you stand and look at the lawn, are you seeing slight depressions that outline each piece of sod that was laid in the fall? Or, is it something more random than that?

For what it is worth, many Oklahomans have red clay, although its density can vary a great deal. Some of it is almost pure clay, while sometimes it is a clayey-sandy blend that is not nearly as difficult to work with. One good thing about red clay is that it is very fertile. Unfortunately, since it compacts down tightly and dries very hard in hot, dry weather, it can be difficult to deal with during those times.

Since bermuda grass is new to you, I'd just like to state for the record that in any other area than its main use as lawn turf, bermuda grass is evil! (This is not the last time you'll see someone here use those words.) It will creep and crawl and get into flower beds, shrub beds, ground cover beds and veggie/herb gardens and will take over and completely dominate those areas. The best way to manage it in non-turf areas is to prevent it from becoming established in them in the first place. Dig it out religiously the minute you see it popping up in a non-turf area. I put down a high-quality, heavy-duty fabric mulch cloth in my veggie garden pathways and cover it with several inches of mulch. When I lift that cloth in fall or winter, I'll have bermuda grass that has invaded the pathway by creeping under the fence and under the landscape fabric and often has stolons that have run 20-30' underneath that landscape fabric looking for an opening where it can grow upward and reach daylight. They are blanched almost white because they've never seen sunlight. That is how aggressive bermuda grass can be.I dig it out of the pathways and put the landscape fabric and mulch back down on the newly 'clean' pathways.

When someone wants to put in a new bermuda lawn, I generally tell them that if they just will rototill their soil, amend it and plant a vegetable garden, they'll have a thriving bermuda grass lawn in no time at all.

Bermuda is a great turf grass for Oklahoma. It handles our weather amazingly well. However, it is not good about staying where you want it, so be prepared to do battle to keep it out of your non-grassy areas.


Here is a link that might be useful: OSU Fact Sheet on Turf Grass

    Bookmark   March 10, 2013 at 2:41PM
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Thank you for the advice. I am going to learn how to grow things in this heat and red dirt. It is a lot different than the black Iowa soil. But, with everyone's help I will figure it out. I just don't want to kill everything. LOL

Thanks again,


    Bookmark   March 10, 2013 at 4:45PM
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Okiedawn OK Zone 7

You're welcome, Steve.

The good thing about bermuda is that you will succeed with it. I don't know anyone who cannot grow bermuda grass here unless they have a serious soil ph issue or too much shade.

As for everything else, it isn't as hard as it seems as long as you chose plants that tolerate prolonged heat and drought some years and flooding rain in other years. It can be harder to find plants that do that in dense clay than in well-drained soil, but it isn't impossible by any means.

I am sure you'll miss the wonderful Iowa soil, which likely was wonderful to grow plants in.

I had black soil in Texas, but it was black gumbo clay, so all I did my moving here was switch from one clay to another.

As Larry mentioned, if some critters are making those sinkholes in your lawn for you, you will become well versed in varmint removal and in filling holes.

Gardening in Oklahoma and the adjacent states is not for sissies. : ) We're a tough, resilient bunch here....just like the bermuda grass


    Bookmark   March 10, 2013 at 7:05PM
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Yes it was wonderful gardening in Iowa. It is hard to believe but I used to have to drive steel posts into my garden and then wire the tall tomato stakes to tie up my tomatos. They honestly would grow close to six feet tall. But, then again that is why farm ground up there will cost over $8k an acre.

    Bookmark   March 10, 2013 at 8:57PM
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We can get six foot tomatoes here too, but many would be hard-pressed to drive steel posts into our red clay very easily. :-)

    Bookmark   March 11, 2013 at 12:01AM
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Okiedawn OK Zone 7

In amended clay soil, my tomato plants usually get 6 to 8' tall by the end of June. That's really not anything special at all here because our tomato season is long and the indeterminate plants can keep on growing taller for a long time.

I've had a tomato plant get 12' tall, but I had to stand on a ladder to pick the fruit and since my garden slopes, I always felt like the ladder and I were going to fall over. Actually, the one that made it to 12' tall didn't stop growing at all once it was coming out of the top of the cages (I had stacked cages to a height of 12' for that plant.). The plant just kept growing and the branches came back all the way down to the ground, so I had a 'weeping tomato'. Once the weeping ends were near the ground, I cut them off so I wouldn't be stepping on them . After I got tired of picking tomatoes from the plant, I hacked it back to a reasonable size and let it regrow for fall.

I routinely use 6' and 8' tall green steel t-posts to stake my tomato cages. Because caged tomato plants grow so large here, on the largest plants I usually have two 8' tall metal stakes on opposite sides of the cage, and then have 3 or 4' tall wooden or metal stakes on the two other sides. Without good strong sturdy stakes hammered as deeply into the ground as we can get them to go, a thunderstorm with strong straight-line winds will knock over plants, cages and all. I start out with one or two 3 or 4' tall metal or wooden stakes for each cage. I don't add the 6 or 8' tall stakes until I see which plants are growing quickly enough to become huge monsters. It varies from year to year depending on where in the garden the tomatoes are planted and on how much rainfall we are having. In a good spring or summer when the plants are getting huge really fast, I'm constantly having to go to the store and buy more green t-posts to use as stakes. No matter how many we have accumulated over the years, it always seems like we need more and more every summer.

Last year, the only tomato plants to get 8' tall or taller were at the west end of the garden where they had late afternoon shade so they weren't as stressed as the plants in full sun, which only made it to 6' or 7' tall. Last year, of course, was a really hard year due to extreme heat and drought, but then we rarely have an easy summer here, although 2004 was really nice.

I grow as much of my garden vertically as I can in order to keep maximum production, so my garden is full of green metal posts by mid-summer.

I feel like dense red clay soil is misunderstood and under-appreciated.

While it is frustrating to try to dig in dense red clay and it takes a lot of organic matter to make it nice and friable, it is incredibly fertile and plants grow exceptionally well in it.

    Bookmark   March 11, 2013 at 12:25PM
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Lisa_H OK(7)

If this was FB, I would be clicking the Like button on Mia's post :) SOOOOO true!

Welcome to Oklahoma! :)

    Bookmark   March 11, 2013 at 12:27PM
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I have Arthritis and have a tough time driving steel post in the hard baked ground. I made gadget that I can bore holes into the soil that makes driving "T" post easy, if there is no rocks.


    Bookmark   March 11, 2013 at 1:34PM
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Okiedawn OK Zone 7


You're really creative. Is your device that bores the holes something like an auger?

I always get Tim to drive the T-posts into the ground for me with a post hole driver....but we're not as young as we used to be, and he moans and groans about it more than he used to.

Except for the posts driven into well-amended clay in the veggie garden (they are fairly easy to remove from the raised beds), we have a rule....once a post goes into the ground anywhere else, we leave it there forever! If it is in unamended clay, I don't think there is any way to get it out of the ground....maybe dynamite.


    Bookmark   March 11, 2013 at 9:41PM
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Dawn, that is just a 1/2" metal pipe flattened on the end and ground to a point. The water spray out the edges of the point and flushes the soil and small gravel out of the hole. I do rotate it back and forth to keep the hole somewhat round. I also use the tool to bore holes around my trees when it is extremely dry hoping I can keep the soil more moist deeper down. (frogs and spiders love to live in those holes also)


    Bookmark   March 11, 2013 at 11:19PM
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