[Mac]

I have a client with a a large number of large Maiden Grass plants and most of them are hollow in the middle - a sign I understand that says its time to divide the plants. However, from a passer-by-ers viewpoint, the grasses look terrific. Would you divide them?

Does anyone have any best practices regarding time of year, techniques, etc? This is a very important client for me and I dont want to unknowingly do something that is counter productive to their health. Thanks for any insights you might have.

[VoodooChile]

Yes. I would divide them because the hollow spot not only will grow larger, but could also act as a gateway for root rot and pests as it biodegrades and turns into more of a hole and collects debris.

Ornamental grasses are best divided in the early Spring. Like all divisions, you should use a sharp heavy clean spade. If the plants show signs of disease (rot, discoloration, fungal growths) I would disinfect between either cuts or individual plants. I would shoot for dividing the clumps into thirds/fourths/fifth/sixths. That will make for plenty of leftover clumps to use elsewhere!

When planting, it is a good time to incorporate some compost into the soil. Avoid straight fertilizer, because grasses become leggy and prone to flop in overly rich soil. Make sure you plant the grasses at the proper depth. They hate being too deep, and will fall right out of the ground if too shallow.

The division process should invigorate the grasses, and insure that they look great for years to come!

[NCSULandscaper]

Dont add anything to the soil when planting ornamental grasses. Most ornamental grasses prefer poor soil and dry conditions. Realistically you can divide them at any time of year besides winter. I even divide in winter but they are in greenhouse conditions to grow field liners for my nursery. Dont worry about doing something wrong with them, you cant kill miscanthus. And there is no set size to the division, it depends on the size you want the new plant. A large clump can produce 15 large sized clumps each. When i divide them for my nursery, i can get 100-150 divisions out of a 3 gallon container grass.

[VoodooChile]

I think the concern with late summer and fall division in my neck of the woods is from frost heave, which would definitely be a problem in Ohio as well. Since the grasses won't have an opportunity to root establish, and they tend to be top heavy, the can flop right out of the ground as moist ground freezes and expands. I guess that isn't a big concern in zone 7 North Carolina. I also find that perennials, not just grasses, which haven't root established before winter tend to be more subject to root rots in wet winters.

As a side note, many of the native nurseries around here recommend all prairie plantings be in the ground by the end of August, but we have pushed that date later with good success.

I do agree that low fertility soils and good drainage are essential for success with ornamental grasses. In Wisconsin, where soils run the gamut from sand to loam but are often heavy clay, division is a fine time to improve overall soil structure with a low-fertility/high bio-activity amendment like leaf-mold or very well composted manure. Depending on the soil structure where Mac landscapes, I would incorporate (till or spade in) compost into the surrounding soil to improve drainage and tilth. This is especially beneficial if there are other perennials in the planting besides grasses.

I would not fertilize or mix anything directly into the planting holes, as that may invert the drainage profile and drown the grasses. In general, soil amendment should be for the entire bed; the old dump some compost in the bottom of the hole approach is a fine example of good intentions with bad results.

Finally, propagules for grasses can be extremely small, but to retain the original integrity of the planting, it is important to put something back in the hole with some heft. I wouldn't go much less than 1/6th of the clump for that reason, unless the client wants to spread maiden grass (Miscanthus) far and wide.

NCSU, is Maiden Grass an invasive down there? I've seen it self-sow in Maryland, but fortunately where we are at in Wisconsin, the growing season isn't long enough for it to set viable seed.

[NCSULandscaper]

certain varieties are self sowing, and we stay away from those cultivars.....

the way to keep the grasses from getting top heavy is to just cut them back, its a grass after all and can take cutting all year long, its just not done because you plant them from the beauty of the full grown plant

the thing with amending the soil for ornamental grass is the fact, it doesnt need it, and they dont care for it. Part of my nursery has plants growing in hardpan red clay, and the grasses thrive in it, growing from a 6" plug to over 6' tall and 4' wide in one year, no fert, no compost, no irrigation. The most common problem ive seen with grasses are they are overly babied, and they dont need to be.

however i do agree with amending areas with other ornamental shrubs and trees

[Mac]

guys, thanks for your insights. Maybe a dumb questions but since Im on a roll, if I do choose to divide them early this spring, that would be after the old growth is cut down, correct? Thanks again. PS, there are almost 50 clumps at this commercial site - anyone near central ohio want any? My client only wants a few for his home and my home can only handle so many.

[Gensparkie]

That's a bear of a job. I hope there's no landscape fabric there! Maiden grass gets so entangled in it, it makes it impossible to deal with.

I'd divide in early spring after they're cut back, and would not add anything to the soil or fertilize them. Definitely the hollow middle means it's time to divide.

[Spartan Pride]

I had to divide just a couple of large maiden grass plantings a couple of years back. Needless to say it was a real pain. The plants took awhile to re-establish themsleves, and only two years later did I see them display the seed stalks that most people find attractive.

You can divide them down really small and they just keep on truckin...