I'm no guru, but nobody else is chiming in, so I'll admit to being a scalper--No secret. It depends heavily on grass type & practices but my Bermuda is a thatch making machine & I live in the dang tropics in Houston, so I take the top off each spring. Rye fescue zoysia may be totally different. They don't survive our 100 degree heat & 100% humidity.

It depends on the amount of thatch build up ........if your entering the spring with minimal amount of thatch , a shorter than normal mow, (not all the way down to the dirt) along with fertilizer may be all you need. If major thatch removal is desired, fall or spring is the time for it, because when the sun gets too high, and the days too hot, even the toughest grasses have a hard time recovering from the battering that a scalp job inflicts.

Thanks. I've got "two" lawns: backyard and front yard. ...

The backyard is mostly tall fescue & turf type tall fescue. I did dormant seed some Kentucky bluegrass there this winter. I don't expect that the fescue creates much thatch.

In the front yard, the lawn of turf type tall fescue and Kentucky Bluegrass. There is a probably some perennial ryegrass and red fescue in there as well. I did a partial rennovation there this past fall, and that included core aeration. I don't know about whether thatch is an issue there.

Assuming that thatch is not an issue for me, should I consider a very low-first cut (but not necessarily a scalping) come spring?

I do it very specifically as part of a process to control thatch--If I didn't have to go through the hassle believe me I wouldn't. Scalping in my book is not just an ultra short cut, but also removal of as much material as possible, therefore bagging is required. I do it as a prep for running my dethatcher & once both are done, I usually end up with 5-8 large black trash bags full of junk. It's hot dusty hard work & its not much fun...

Yep, you for sure don't want to be scalping bluegrass/fescue type yards. A little shorter cut to remove older leaves, to make room for new is ok. reeljake- Do you have hybrid bermuda?

My front lawn is about 3 inches tall right now, although a lot is matted so it's likely much taller but isn't growing upright.

The backyard varies; some is about 2 inches tall (growing upright) and the rest is about 3 inches tall (but matted, so probably much longer).

In both the front and back, the matted areas are growing more prostate instead of upright. It's as if the grass doesn't have the strength to hold the blades upright. We've had a fair amount of snowfall for Central VA so I imagine this is expected...

Given these conditions, maybe it would be good for my first cut to be about 2.25 inches tall? Not really a scalp, but enough to get the weak blades out of the way? I normally mulch all clippings, but I think for this cut I would bag them?

My Bermuda is hybrid, 419. I have one small golf area that's seeded Bermuda triangle, but it doesn't really get thatchy thanks to overwhelming amounts of earthworm activity on that side of the yard.

You could probably go down to 1 1/2 without any problem. Yep, jake, 419 produces tremendous amounts of thatch, and thats why a lot of golf courses are moving away from it- for fairways. Bermuda Triangle is about 30% less thatch, which makes a big difference when your talking about many acres of turf.

The segment length between leaves on the Bermuda triangle has been really impressive, like 6 leaf sets per inch, but it won't spread very well for me. The 419 sends runners all over the place but I can't get that kind of leaf density out of it.

You may be dethatching too much. Have you ever tried scalping a bit, not any shorter than 3/8, a couple of times a year, with a reel mower only? This keeps a lot of stems and runners intact.(preserves density) Ya, i noticed that about Triangle too. Mohawk will send out long runners if its planted as a single variety, but when its combined with the other two strains, its almost like they hold the mohawk back. Really weird !

I use my 7blade McLane to scalp, then transition to the rotary after grow in. I do the scalp & dethatch only once a year & I hope one day the worm activity spreads across the whole property & I never have to do it again. One day maybe....

Yep, it depends on the grass.........bermuda and zoysia have extensive rhizomes , which will sprout new growth, even if the area is scalped to the dirt. Bluegrass has rhizomes , so i am wondering if you could take it down to 1/2 , and still have it survive? (as part of a spring renovation )

You could and it'll come back, but it'll look like crap until the weather warms and growth resumes (round these here parts, that can be mid April). Plus for KBG, there's a given amount of resources stored in the root systems for spring, so forcing regrowth taps those more than simply letting it come back by itself would.

Not that the same isn't true for dormant Bermuda, but it simply seems to handle being abused like that much better.

For the 2.25" cut --- should I plan on bagging? (I normally mulch). I've got some KBG dormant seeds that hopefully will be sprouting by the time I want to cut, and I am be worried about the clippings from that first low cut smothering the babies.

I don't think it will hurt tall fescue or KBG, but I don't think there's any reason to do it either. Let it grow to 4.5 then cut to 3.5 as usual. The seedlings will be ok. I used a substantial layer of grass clippings and thatch as ground cover for the seeds last fall and they poked through just fine, though I was kind of nervous for a while there.