Mine don't seem to flop. Here's a couple of photos of them. I've had them for several years and they are more beautiful every year. Just don't overwater or fertilize and yuo shouldnt have a problem.

Blackie

My Morning Light has shown no inclination to flop whatsoever.

Neither has mine.

nor mine.

Ditto

'Morning Light' is a wonderful grass, but can anyone tell me from personal experience just how tall it gets? It's exactly what I want as a backdrop for a garden sculpture; however, I want a grass that won't completely obliterate the view of the garden behind the stand of grass. I have read that it grows to 4' tall, and another garden label indicated that it could get to be 5' tall (these heights would be fine), yet another tag cited that it would reach a staggering height of 7 feet! Please let me know how tall they have gotten in your gardens, as well as how many years it took them to reach their mature height. Thanks for your input!

Blackie's 'Morning Light,' pictured above, must be every bit of 7 feet tall.

Mine in 5b is over 5 feet in bloom.

It might not like the soil left behind after the Pine tree was removed....

I agree with Webcat5. I've never seen anything growing under a pine tree. What it does to the soil is it's defense system to keep away any competition for water.
Have the soil checked and replace if needed or try something cheap first.
As to the height my Perennial Guide says 5-6 ft. and I do think the warmer zones increases the height due to the extended season and heat.

Rory

"I've never seen anything growing under a pine tree."

Now you have:

{{gwi:244889}}

That White Pine is 70+ years old, and larger than 3'DBH. What you see is growing within 5' of the north side of the trunk. Other occupants of the bed include Daffodils, Crocosmia, Rosa rugosa, a huge unidentified coniferous shrub and several Luzula nivea.

I don't think the problem would be the ex-Pine tree's soil, unless it's 90% sawdust from grinding the stump.

Yes, while many plants will grow under a Pine tree, some are susceptible to the allelopathic response of certain species of Pines...

The needles (after they are dropped) break down into the soil which produces a high acid content in the soil....

This is a natural defense of the tree to attempt to alleviate some water/nutrient competition....
This defense was developed by the tree for a reason...

If the tree was recently removed, the soil should have been tested to determine the acid content and then reconditioned as needed to help reduce the poisons....or simply a trial and error will be your only other option.

Acid loving plants, like Azaleas, or even those who don't seem to mind, like Hostas or Heucheras, will do great...grasses prefer a much more neutral soil, however...