Mulching weeds

[moe lasses]

Here is an easy question that I have always wondered about.
If I cut crab grass with my mulching mower and I leave the clippings on the lawn, am I spreading seeds that will propogate?

[khwoz]

I guess no one knows. If the grass hasn't formed seed head, the answer is NO. It doesn't matter what type of mower you use; they all distribute seed. The key is to have a healthy soil for the Grass & choke out the undesirables.

[Dchall_San_Antonio]

Somewhere I read that crabgrass only goes to seed late in the growing season. If that is true you can mulch away on it without fear.

HOWEVER, assuming you have a St Augustine lawn, if you have crabgrass in it you are doing something wrong. Weed seed, including crabgrass, needs daily watering to sprout the seeds. You can't stop Mother Nature from dealing you a dirty blow but if your irrigation system is set to water daily, or even every other day, reset it to stretch out the watering frequency. Start at every 3 days with a goal by the end of summer to be watering only weekly. You'll have to water longer each time to reach the goal, but you can get there. I water each zone for 1-3 hours and my zones overlap by 50%.

Now if Mother Nature gives you daily rain for a week or so, you will get seeds to sprout. If you have dense tall grass, those weed seedlings deep down in the shade of the wide-bladed St Aug will not photosynthesize enough to develop a root. You can control that, too, by resetting your mower to mow at the highest setting. With St Aug there is never any reason to reset your mower once it is set high. As a special note on this, if you plan to ask the neighbor kid to watch your lawn during the summer, you might want to weld the wheels at the highest setting, because it ALWAYS happens that he'll want to do you a favor and mow it nice and short for you.

[e Craig]

And there's another point to consider:
I've been told that weed seeds last 30 to 40 years, waiting for conditions to be right to germinate. You're worried about only this years crop? There may be already 30 to 40 times that much in your inventory!

[moe lasses]

Thanks for the great info!

I think I am getting to the root cause of the problem (no pun intended).
I am pretty sure that my watering habits are in check because I only run zones manually when needed, usually about once per week at short durations depending on the need.

Last fall during my last mow, I cut one section of my lawn too short like an idiot...

The section I did not cut too short does not have as many weeds because my grass has come back. The section I cut too short has a plethora of weeds while my St. Aug/Bermuda mix is strugging to come back. This is coupled with all the rain we have had here in the DFW area.

I know my soil is very healthy since I have fertilized with corngluten meal during the proper times, along with applications of lava sand and Garden-Ville 7-2-2 (good stuff).

I guess a good point to remember is that no matter how good your soil is, weeds do well when there are dead spots of grass.

Given all this discussion I will mulch my weeds back onto the lawn even-though the crab grass (and others) has seeds.

[e Craig]

Moe,

I am troubled by only one point in your summary
Quote: I only run zones manually when needed, usually about once per week at short durations depending on the need.

May I suggest, take another look at David's watering schedule, he's watering longer. Further, if you are watching for the need as closely as it seems, you may well find that you can go for more than a week B/4 watering. The dry soil surface may discourage the weed germination while the established roots are sustained by the deeper water!

Take care.
Craig

B E - A L E R T !
The world needs more Lerts!

[Dirt Doctor]

There is little crabgrass growing so far and no seed heads for sure. Mulching the weeds whatever they are is a good idea. I agree with Craig to water less often.

[moe lasses]

Very interesting...

Then what I have been infested with is not crab grass.
Mine definitely has seeds (Lots of them).
It pulls out pretty easy.

I have tons of little green clumps all over the place with multiple strands of seeds. I have been searching on the internet today trying to ID this thing.

I will plan on taking a picture and posting it.
I would like to know just what I am dealing with.

[moe lasses]

Here is the CUPLRIT! It is annual bluegrass, or poa annua.

http://www.ipm.ucdavis.edu/PMG/P/W-GM-PANN-MP.001.html

Ok, so if I mulch these seeds when I cut the grass, am I spreading this for the next cool season?

Seems that I have gotten more of this over the years eventhough I have improved my soil conditions and used CGM in the fall and spring during the window of opportunity.

Kind of frustrating, but I guess I brought it on myself when I cut my lawn too short last fall. Still kicking myself for doing that...

[e Craig]

Hmmmm, interesting!

I like the way you stay after a problem. May I suggest, again, that you check out the watering schedule.

It is discussed more fully in
http://www.dirtdoctor.com/forum/viewtopic.php?t=7501

Take care.
Craig