The local feedmill supplier for the Corn Gluten Meal - he just told me that the soil is frozen still and I just measured the soil temp at 46 degrees Fahrenheit! He said he measured it this morning. So obviously there is a wide daily fluctuation. He said he was waiting for a better deal for me so I said I would rather make sure I get the Corn Gluten Meal in time before it germinates.
24-48 hoursCrab grass seeds will not germinate until soil temperatures have reached a sustained temperature of 55 degrees for 24-48 hours.
So the thing is that next week will hit high 60s early in the week. It's going to warm up fast. Also we need to make sure there is rain to break down the proteins into the dipeptides so act as the growth inhibitor.
Ideally it will be spread right AFTER a rain - to make sure the powder doesn't get too dusty and instead sticks to the ground. Then there should be another rain within five days but NOT too much to drain off or wash off the powder.
So it only needs a quarter inch of water.
It's a tricky proposition but earlier is at least betting on the side of safety margin in terms of making sure to catch the Crabgrass before it germinates.
https://app.gisdata.mn.gov/mda-soiltemp/
So according to this site of Soil temperatures - it matches the reading I got as well - even though the closest station are farther north or to the west.
So the Feed Mill supplier claimed that because Becker Minnesota is SAND then it will be warmer than here even though it is farther north. But actually the temp is lower than here.
So
You should be careful not to apply crabgrass preemergent herbicide too early because it will break down and become less effective. Most good crabgrass pre-emergent products indicate that it is a good practice to water the lawn a few days after application in order to wash off the concentrate into the soil.
My guess is that this Spring will be WARMER than last Spring - due to abrupt global warming. That is the climate trend.
So let's say he gets in the pallet of Corn Gluten Meal mid-next week and he calls me the week after.
Crabgrass seed germinates at a soil temperature of 55 degrees, as measured four inches down. Ideally, you want to apply the material about a week before that — just as soil temperatures reach around 50 degrees four inches deep. We are not there yet.
https://wtop.com/garden-plot/2015/03/garden-plot-almost-time-corn-gluten-meal/
Yep - look at those soil temps according to GDD Tracker - it's DEFINITELY much warmer than last year. So no time to just go on "hunches" from previous years!
The weather app or website can give you the past two week overnight low temperatures in your area. Just average them all together and you will have a very close representation of the soil temperature.
So that's the AIR temperature.... OK....
Did you know that most broad leaf weeds start to germinate, with ample moisture, at 45 degree soil temps? You do now ... I just told you. What can we do with these bits of information? We can apply Corn Gluten Meal, an organic fertilizer and pre-emergent weed killer near or at soil temps of 45 degrees
There you go! It's not just for Crabgrass but any annual "weed."
Being mostly surrounded by concrete a filling station’s landscape will have a slightly higher soil temp than your home’s landscape and lawn. So when the filling station’s landscape starts producing weeds, your landscape and lawn is about a week or two behind so that means it’s time to get out there and broadcast Corn Gluten Meal!
Exactly - we have a lot of black top with lots of little lawns - so they warm up a lot faster!
Oh ... if we get heavy rains soon after applying your Corn Gluten Meal, you will need to do it again. Sorry, that’s just the way it is, I don’t make the rules. Get used to putting it out a couple of times in the spring for a high percentage of effectiveness for broad leaf weeds. What about grassy weeds? Well they germinate around 55 degree soil temps.
hmmm.
The GDD model attempts to predict the optimum application timing for when the 0-2 inch depth soil temperatures consistently reach 50-55 F. Applications made at this time provide adequate time for the preemergence herbicide to be applied and watered in before crabgrass germination occurs.
So the key is to GET the rain but not too much!
Based on the weather forecast, it looks like southern areas of the state may enter the optimum application window within a couple weeks, but remember in most years we stay in the optimum application window for at least a couple weeks, if not longer.
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