An indoor test tried to compare soil preparation for overseeding using four types of seed in small containers. Bare soil resulted in the tallest seedlings and best germination.
At day 9 the tallest perennial rye was on bare soil at 3.5 inches. The perennial rye sown on top of the "thatch" was second tallest at about 3 inches. The perennial rye sown with thatch applied on top of the seed (like straw on top) was at about 2.75 inches.
Fine fescue growth was nearly the same on bare soil and sown on top of thatch. Seed under thatch was sparse and slow to arise.
Tall fescue was similar in germination and height on bare soil and on top of thatch, it was slower where thatch was applied on top.

Kentucky bluegrass was about 3/8 inch tall at the maximum. Sown on top and under the "thatch layer" results were not yet visible--or only slight germination.

In photo, top row: thatch on top of seed, second row bare soil, bottom row seed on top of thatch.
In photo left to right: perennial rye, fine fescue, tall fescue, Kentucky bluegrass.

 

Four types of seed were compared indoors in containers. A pinch of seed was sown on soil, on top of thatch, and under dead grass clippings (under thatch).
Seed sown on topsoil sprouted best. By day 13, seed sown on top of thatch was slower, but otherwise about equal. Seed under a layer of dead grass (like a straw mulch), was slower yet. The bluegrass sprouts were small and barely visible in the photo.
An hour outside at 27 degrees caused no harm.

 

All grass types were moved outside for 20 hours, where the overnight temperature was 17 F. The soil froze. The pots were then moved inside for 48 hours, at 68 degrees.
The tall perennial rye was damaged and mostly collapsed, except for the short leaf blades.
The fine fescue (CRF), tall fescue, and Kentucky bluegrass were also damaged, but less so. Bottom photo.

 

I’m not sure what we can learn about our lawns by exposing seedlings to periods of cold temperatures. The seedlings are very young and most likely somewhat fragile because of that. The grass in our lawns also have an advantage in that they get a chance to harden off and prepare for winter by storing food in its root system as daylight hours and outdoor temperatures gradually fall with the expectation of winter.

In spite of knowing all of that, I have to admit that your experimentation with cold temperatures is very interesting. I’m looking forward to your next update.

For anybody else that may be interested in this, 20F is the temperature that winter kill becomes a possibility if temperatures drop rapidly below 20F for cool season grasses.

 

Good point, Kerb. Very low light levels inside. The temperature drop was rather abrupt 68 to 17 F. in five minutes. It appears that a good frost would not hurt newly seeded grass--so seeding late in the year might be a bit slower, but it should still work. A sudden snap to really cold (17) with no gradual transition--maybe not. In your town maybe that is just a chilly day, right?

It appears that perennial rye was more sensitive to the cold--or maybe it was just taller (about 4 inches). Fine fescue appeared to be more resistant to the cold. Blue and tall fescue were almost as resistant to cold as the fine fescue.

Suggestions? I am running out of ideas to test.
I have some Mini-clover seed which would be good for a weed killer test. And I could plant some tomatoes.

 

When we get cold snaps around here the air temperature can get cold pretty fast but the soil retains its heat. The 20F temperature I mentioned is for soil temperature. Around here once the snow melts in the spring we still get many hard frosts and freezes that turn any remaining green grass that was hiding under the protective layer of snow brown and desiccated. Our lawns then begin to grow with warmer temperatures from the crowns and roots.

I think we can assume that when you exposed your grass to the cold for 20 hours that the soil temperature must have reached that same temperature (17F) or very close to it. I expect that you should certainly see some leaf damage but I’m wondering if the grass will grow back from the crowns or roots now that they have warmed up again.

From what I’ve read, the rye should be the first to experience damage and loss. Interestingly tall fescue is said to be damaged more by being submerged in ice than just exposure to cold temperatures.

Hopefully you haven’t already discontinued the experiment. There‘s more to learn!

I’m interested in how my dormant overseeding of rye is going to react to an application of prodiamine this spring but I don’t have access to any to experiment with so I’ll just wait and see what happens with that. If I’m able to think of anything else I’ll be sure to mention it.

 

I’ve always wondered what the soil temperature really was under the blanket of snow we get here. I know that we can get over three to four feet of frost in the ground over the winter but freezing and getting below freezing may be two different things outside in the lawn.

I’ve also always wanted a good home weather station but just considered them too costly, but I broke down this year and bought and installed a Davis Pro weather station along with the optional soil temperature and moisture sensors. I’ll finally get to see what really goes on out there in the lawn this winter.

The soil temperature and moisture sensors are located in an open and sunny area of my lawn four inches deep in the soil. We have had a couple of inches of snow cover over the last eleven days with night time air temperatures frequently below 20F and the soil temperature is still just reading 33F.

If you’re interested and don’t mind me posting in this thread I could drop in periodically and let you know what’s happening with my soil temperatures.

 

Sure, Kerb. That would help everyone.
My soil temp 5 minutes ago is about 30 degrees at 2 " deep under 6 inches of snow. Officially at a nearby ag weather station it is 35.7 F.
https://enviroweather.msu.edu/run.p...su.edu/run.php?stn=hvl&mod=w_sc&da1=2&mo1=12&da2=16&mo2=12&yr=2017&mc=397&ds=cd

 

Lol, Maybe I’m the only one that doesn’t know what goes on under the snow!

 

I got rid of the grass and planted "Mini-clover", indoors (in paper cups). It came up to a maximum of 1/4 inch in 48 hours. The mini-clover is now about an inch tall.
It is from Outside Pride which has other types of seed and grass seed for sale online. They also list 188 ground cover seeds. Only ajuga is listed as suited for partial to full shade.

https://www.outsidepride.com/seed/clover-seed/miniclover.html

Not sure--still want to come up with a good idea for an experiment. This may come out as an indoor herbicide test.
Any ideas? Suggestions? Should I plant more grass? I have four species of seed.
?Seed after Roundup?
Effect of Milorganite or other fert?
Seed in aeration holes?
It is just a hobby.

Temperature was 4 degrees F last night--about 12 inches of snow on the ground. Soil temp--maybe I can check tomorrow.

Tomorrow, hopefully I can check on which herbicides have frozen. Same as last year, I suppose. Only one I have noticed so far: a generic 3-way has frozen.

 

Hey Riggle, did any of the grass that fell victim to the cold grow back, or was it permanently damaged (killed) by the cold temperatures?

Maybe you could try an experiment to see if a heavy dose of Milorganite works as well as the standard dose of starter fertilizer, but I’m not sure how to set up that experiment or even how much of each fertilizer to use.

We have had about a week of temperatures with lows below zero and even some highs below zero. It’s been 14 and 15 below zero the last two mornings and my 4inch soil temperature is still hanging in there at 29F but falling very slowly. We only have about two inches of snow on the ground right now. We are short on snow this year.

 

Good point, Kerb. Dig up some snow--is the grass still green underneath? Does it stay green--then turn brown in spring--and then come back as new growth from the crown?
I will check my yard. It got down to 4 degrees last night, we have about 12 inches of snow on the ground.
Everyone check this--OK!

Perennial rye seedlings in cups were most damaged by 20 hours at 17 degrees--partly because it was taller--about 4 inches. Shorter grass, (less than 2 inches) like short shoots of red fescue, bluegrass and tall fescue appeared to be undamaged. It appears there was not enough light (west window on dark days) for recovery of the damaged grass. Grass plants discarded.

Good idea--Milorganite--heavy dose. Is this as good as starter fert? How to measure? Maybe use an eighth of a teaspoon per cup.
Milorganite could supply phosphorous, nitrogen, organic matter and micronutrients. Not exactly mulch or topdressing--but a lot easier to apply. I think the label suggests one to two bags per thousand sqft for new seed. Is there a chance germination would be better? Worse?

http://www.milorganite.com/lawn-care/lawn-care-basics/seed-and-sod-application-rates

 

If you'd like to extend your experimentation this winter, a fluorescent light fixture would be of great value to you.

If you happen to have a desk or clip light like this gathering dust somewhere, https://www.amazon.com/dp/B01N2IE7H...=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9019691&hvtargid=pla-334926905914

You can buy one of these bubs for it https://www.homedepot.com/p/Philips...jagOR|dc_mtid_89037lm25188_pcrid_227841299674_pkw__pmt__product_203349671_slid_ to light your plants with. That's all you need to grow plants indoors.

I use a cheap shop light like this to overwinter some plants for my wife and I. https://www.homedepot.com/p/Lithoni...t_203081577_slid_&gclid=EAIaIQobChMIoNDX8Ie32AIVirjACh1kRwCaEAQYASABEgJb4_D_BwE

I put it on a light timer and never have to think about it.

 

The last two winters we had heavy first snowfalls that kept the grass green all the way through snow melt, then after a few more nights of freezing temperatures the grass turns brown and looks completely dead before the soil warms enough for new spring growth. That situation leads to increased snow mold as the mold thrives on the lush green grass as the snow melts.

This year has been different. We haven’t received much snow yet and the grass turned a little brown before a couple of very light snowfalls. I expect snow mold to be less of a problem this year.

With a good kitchen scale you may be able to apply the correct amount of fertilizer to your cups. I think you would need a scale that can measure to grams. Possibly if you know how many granules to use per square inch or foot from some of your spreader calibrations, you could do the math and count them out.

 

I recycled part two of the cups of soil, after pulling out and discarding the Mini-clover. I planted new perennial ryegrass seed on bare soil (on surface--no preparation), and then secondly, seed with Milorganite on top. I used a quarter teaspoon which I calculated to be about 92 pounds Milorganite per thousand sqft--approximately. Seed was planted January 2, 2018. On January 7, after 5 days, about 4 sprouts on bare soil, attained a height of about 1/4 inch.
On the Milorganite-amended soil there was one sprout. Temperature was about 67 F and 64 at night.

Hopefully I can test with seed germination after use of a glyphosate product and a three-way herbicide in the next week or two.

 

Heavy rain last week--about February 22nd, 2018. Snow melted--soil temp was 32 today. There was a frozen layer a couple inches deep--but it was easily penetrated with the soil thermometer.
Everyone --what is the soil temperature in your town?

No sign of seed germination. This in spite of a couple days of 60 degrees. It is 37 right now.

 

The soil temperature in my lawn at the depth of 4 inches is currently 31 F. The lowest soil temperature I have recorded is 27 on January 6th, 7th and 14th, when we only had a couple of inches of snow and the daily lows for air temperature were around 20 degrees below zero. Otherwise the soil temperatures have mostly been in the 30 to 31-degree range.

This is the first winter that I've had a remote soil temperature sensor to make these kinds of observations with. Over the winter, the soil freezes to a depth of 4 feet or so on average here. I suspected that the soil would stay warmer than the air temperature, but I admit to being surprised at how deep the frost can penetrate while the 4 in temperature hovers close to the freezing point.

I found a couple of fun articles about soil freezing that will be interesting for many of us Lawnsite members and explains some of the things that are quite familiar to the northern landscapers and irrigation people.

https://www.joneakes.com/jons-fixit-database/2149-Overview-Soil-and-the-Spring-Thaw

https://nsidc.org/cryosphere/frozenground/how_fg_forms.html