My first thought is to religiously avoid any fertilizer in the future. Panicum only needs ferts when it's very young, and detests it in later years. Fertilizer tilts the delicate balance between foliage growth and stem strength. If you stimulate the growth of foliage, the stems can't support the weight, especially when wet.

My next thought is it may be time to start the process of thinning the mature plants by division. With as many as you have, this is a daunting task, but the older they get, the more they need it. In your case, I'd probably do it by removing all but a small bit on the outer perimeter of each plant. This is the youngest part of the plant, and will grow with vigor after being freed from the older parts of the plant. Use a very stout, sharp nursery spade, and simply cut out and remove at least 3/4 of each plant, leaving only a bit of the perimeter growth. Fill the hole with plain soil. It'll fill in quickly, and be much stronger.

Finally, $2,000 to mow and remove a half-acre of grass sounds terribly exorbitant. I can't imagine why it would cost more than a few hundred dollars, at the most. For a few hundred, you could rent a brush hog, and cut it yourself. You could probably rent a shredder for even less, and shred the cuttings for mulch/compost. If you live in an area which allows it, consider a controlled burn each spring. This kills two birds with one match. The grass will love it, and you'll save a bundle. Do the divisions soon after you burn the field. By mid-summer, your patch will be gorgeous.

The only thing that could have caused the collapse is over-fertilization. Once established alot of the native prairie grasses do better the worse they are treated. Native prairies by nature don't get much annual rainfall and soils are relatively infertile. That is why they are prairies and not forests.

I second everything else donn said.

One of the best investments I ever made was a chipper/shredder (about $600). You will look foward to raking the leaves and cutting stuff back due to the compost you'll get from it. And you'll get your money back with the savings from not having to buy soil and fertilizer.

I just came to look on the forum here for the exact same problem. My Cloud Nine has become a low-lying fog. I just planted them last fall but they were good sized and in large pots. I only have 13 plants in a group and we have had some heavy rains recently. It was starting to recover a little then yesterday heavy rains have the Cloud Nine sprawling again.

I did use some Nutricote fertilizer earlier in the year so maybe that is my problem as well. It is too bad because it was really starting to look good. Is it a lost cause for this year or should I consider staking them perhaps? These are next to a swimming pool and I still have a couple more pool parties planned. Thanks.

I agree with others that fertilization is not really a requirement for prairie grasses. I think, though, that under a more normal weather year, the foliage wouldn't have been so bad off. Extreme drought followed by periods of very heavy rain don't make a good recipe for a strong plant. My guess is that in a more normal year you won't see this occurring.

Staking, stringing, and other methods to contain will work, but when faced with a meadow style planting, this just isn't feasible. In those cases, cutting back and mulching the debris is the best solution. I never recommend controlled burning as a solution unless you really know what you're doing, but that is also an option as Donn suggested.