Ornamental Grasses

Ann-Marie Volz • January 14, 2025

Know what you are getting into with ornamental grasses.

Ornamental grasses are often considered low maintenance plants.  I love ornamental grasses, my garden sports two types, a false pampas grass and a maiden grass, but they do require more care than the shrubs planted nearby. While they are prized for their deer resistance, elegant plumes, and gracefulness in a garden, homeowners looking for "set them and forget them" plantings should carefully consider their grass selection before planting one or dozens.

The genus Miscanthus, which includes the many varieties of maiden grass, is very popular and probably the highest maintenance grass I have ever worked with in a landscape. It is a majestic grass, and there are several species and cultivars available. The most common are Miscanthus sinensis, which includes 'Morning Light' and porcupine grass.  Like all most ornamental grasses, they do  need to be trimmed down, either in the fall or the very early spring.  But these clump forming grasses grow rapidly and can reach six feet in height with tremendous spread. The trimming down and hauling away of each season's growth becomes a bigger task every season. From one landscape, I take an entire truckload of grass tops every autumn.

Eventually, these grasses expand so much at the base that they need to be divided. Depending on soil, light and moisture, this can happen as quickly as their second or third season in the ground. Compare that to most other landscape shrubs, most of which never require dividing.  Failure to divide or thin these specimens results in grasses that spread awkwardly, are devoid of growth at their centers, and lose their graceful appearance.  When they reach that point, lifting an established ornamental grass out of the ground is no small task! From my experience, this dreadful chore can be made easier by NOT lifting the grass out of the ground at all, but by digging out only the parts of the grass system that have grown out of bounds. Still, it is a rough sport. The blades are sharp, and the roots hold tight.  

The Pennisetum, or fountain grasses, that will tolerate our zone, formerly zone 5 now 6a, are beautiful when mixed with evergreen plantings or to accent stone walls. The fuzzy light colored blossoms of the 'Hameln' grass are a wonderful contrast to Blue Spruce (Picea pungens) or the burgundy red foliage of Ninebark (Physocarpus). Yes, they need to be trimmed back as other grasses do, and eventually require dividing to repair an empty center, but their compact size eases the pain a bit, most varietieds stay between three and five feet tall.  The Pennisetum 'Rubrum' has gorgeous burgundy foliage and pink to reddish blooms, but it is an annual here. Use it in containers, but don't expect to see it in your garden next year.  Unlike Miscanthus grasses, some Pennisetum varieties will reseed themselves and are considered invasive in some places. 

When digging out only a part of the clump of a large established grass, it is best to complete this task in the spring, as new growth emerges.  This gives the grass an entire season to recover.  I fill in the void space I've created with fresh soil.  The established grass won't know what happened, and though you may have injured a few small spots, your grass will be eager to regrow in the spring.  And now you have a clump of rhizomes you can plant elsewhere, or better yet... give away. 

The genus Calamagrostis includes the feather reed grasses, which are some of my favorite to work with.  'Karl Forester' is a cultivar I love to employ in landscapes. It grows slowly and dutifully retains it's shape and form for years.  They tend to grow upright and then arch slightly, compared to the maiden grasses, which grow in a wide fountain. This makes placing them in the landscape a little easier.  This is a better grass for homeowners who want an easy to grow and maintain ornamental grass. For homeowners who prefer to chop their grasses down in late fall because they prefer a tidy winter landscape as opposed to an interesting winter landscape (not judging!), the advantage here is the early blossom.  Unlike the later blooming Miscanthus and Pennisetum grasses, the feather reed grasses will give you lots of time to enjoy their plumes waving in the summer breezes. I typically trim these grasses in the spring, though some homeowners prefer I do it in the fall.  They are smaller in stature than the common Miscanthus or Pennisetum varieties, and that translates into far less waste material on trimming day. 

The genus Molinia includes the mysterious sounding purple moor grass, and as it's name suggests, it thrives in a somewhat damp but not waterlogged area such as the moors of Scotland.  It can be invasive so I stay away from using it and recommend you do the same.

Panicum, or switchgrass, were a large part of our prairie grass heritage, so they grow well here.  And isn't it nice to finally consider a native grass for our ornamental grass needs? 'Shenandoah' has my vote for the nicest cultivar in town.  It's compact, growing about three feet tall and sports red tipped foliage that gets richer all season long. The blooms are delicate and also carry that deep reddish pink color that contrasts so well with our evergreens and stone walls.   If you like grasses for winter interest, than nothing beats this grass, as it tends to stay more erect than other grasses left up until spring, even after heavy snows.   It scores even more points for providing nectar to butterflies and seeds for wildlife.  

No matter what grass you choose to buy and plant, and there are many more than those I mentioned here, please plant early in the season. From my experience here in Northeastern Pennsylvania, ornamental grasses need to be well established to survive our winters, and that takes time. And above all, LOOK CAREFULLY AT THE TAG. Many ornamental grasses are labeled perennial because they are, but not here. We are zone 6a, but more like zone 5 in some places!

Happy planting!

Know Your ZONE.

By Ann-Marie Volz • January 13, 2025
Understanding the new Hardiness Zone Map and how to choose the right plant.

Landscape Fabric

By Ann-Marie Volz • February 12, 2022
Landscape fabric is a real pet peeve of mine. I have ripped out so many hundreds, maybe thousands, of feet of landscape fabric in my time that I would, if I had the money, take out full page adds in every major publication to tell people to STOP using it in gardens. However, it does have its' uses, as you will see in a moment. First of all, landscape fabric is often sold as a method of weed control. So, let's discuss weeds for just a moment. Weeds that grow in your garden arrived there by one or all of the following ways. They grew from a weed seed that was blown into your garden by the wind or transported there by an animal (i.e. bird droppings) or insect. Or, they grew underground from a nearby location. Some weeds (which is any unwanted plant) can grow very long distances underground! Members of the mint family travel quite well this way. Finally, weeds also grow overground. Ground ivy, a bane to lawn lovers and gardeners alike, is this kind of traveler. Now back to fabric. Fabric will not stop any weeds from growing in your garden. As for the weed seeds, they will sprout in mulch or even stone and the fabric you've painstakingly put down may slow their progress. But most weeds have roots so fine that they can and will weave through the fabric. If you get them before, or just as that process starts, well then, you can say the fabric worked. And by get them , I mean WEED. So, now you are busy pulling weeds so that they do not root into your fabric. How is that different from weeding so that weeds do not root into your soil? I wonder! If you don't get that weed in time, then the roots will grow and when you try to pull out that weed, you will tear your fabric and, very likely, leave enough root matter behind for the weed to grow right back, and better, now that you've made a nice hole in the fabric. As for weeds that grow underground, now there is a real danger to gardens and landscapes. Why? Because those underground runners are looking for a place to surface and grow. I have lifted fabric in established gardens to find massive networks of such roots and runners. Sadly, they often surface at the crown or your plants, that is, where you have cut a hole in the fabric to plant your flower, or shrub or tree. And, chances are , you will not notice it down there until it is far too enmeshed with your prized plant to ever get it out. This is a terrible thing and I've seen it happen over and over again. Those underground roots and runners will also find a place to surface at the edge of your garden, where the fabric stops. And they will surface and grow there with reckless abandon. At that point, the unsuspecting gardener will start pulling, and discover with dismay, that everything they are pulling is attached to long roots and runners. And now, oh what a mess, the fabric is completely pulled up! Fabric may more successfully slow down the progress of weeds that spread by growing overground. And, it may be easy to pull these culprits out of the garden as they struggle to take hold through the fabric. But of course, that amounts to diligent weeding, and I'm pretty sure most people buy and use fabric because they think they will not have to weed. Still, I am a professional gardener and I do buy landscape fabric. Why? For two reason and two reason only. Number one, fabric, even if you have to use cheap fabric, should be applied under stone and gravel. Notice that I have it employed in the picture above. It provides a barrier that prevents your stone and gravel from sinking into the soil below over time. Weeds sprout in stone and gravel eventually, but can be treated with a dash of boric acid, or some other natural herbicide. After the weed dies, it can be removed without making a huge hole in the fabric. Number two, high quality, non-woven fabric can be used by itself as a pathway in vegetable gardens. It will get slippery, so care must be taken to keep it clean. Non woven fabric has the look and feel of thick felt. And it is the only fabric I will use in my two exceptions for using fabric. Here are two more reasons to avoid fabric in gardens and landscapes, which have nothing to do with weeds. Gardens are a process. The soil around your plants should be cultivated from time to time, and amended with organic matter. If you use natural mulch, it is supposed to break down and be reapplied every so often. You can't do any of that when fabric is present. And the truth is, all fabric will eventually get ripped out and thrown into a landfill, and I think it is high time we all become more conscious of how much we send to the landfill! There are those who use fabric seasonally in vegetable gardens. I used to do this myself. But I have been converted to using straw or hay or cover crops. Any or all of which look better, work better, save money, and return organic matter to the soil. So, in conclusion, if you are going to have to weed anyway, why spend your time and money on fabric? But if you are doing anything with stone or gravel, make that anything last longer and cleaner with a layer of fabric beneath. Your comments are welcome! Gardeners learn from gardeners.

The PH Scale

By Ann-Marie Volz • March 8, 2019
Baffled by PH? This post will help you understand the basics.
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