Most ornamental grasses in our gardens are hardy. But some of them still need some protection during the cold season. Here is what you need to know about wintering ornamental grasses in beds and pots.
Tie them together, wrap them in fleece or cover them with mulch: there are many tips circulating on how to overwinter ornamental grasses. But it’s not quite that simple, because what protects one ornamental grass in winter can actually harm another.
In general, the majority of all perennial ornamental grasses that are offered for sale in nurseries and garden centers are winter-hardy in temeprate climate. Nevertheless, there are some sensitives among them, which are happy about additional protection in the winter months, whereby for many of them it is not even the low temperatures that are the problem, but the winter wetness or even the winter sun. The type of wintering depends on the type of grass, the location and whether it is deciduous or evergreen.
Wintering ornamental grasses: This is how to do it.
As mentioned earlier, not all ornamental grasses need winter protection, even though you see wrapped or tied grasses in many gardens. Rather, the opposite is true. Excessive winter protection can actually harm some species. Ornamental grasses, which prefer dry soils, suffer much more if you wrap their clumps with fleece or foliage, as winter moisture can accumulate underneath. The result: the plants begin to rot.
Blue fescue (Festuca glauca), giant feather grass (Stipa gigantea) and blue oat grass (Helictotrichon sempervirens), for example, react very sensitively to such wrapping. On the other hand, this measure is absolutely recommended for the wintergreen pampas grass (Cortaderia selloana) and giant cane (Arundo donax). Their leaf heads are tied together in the fall, surrounded with dry leaves and then wrapped with fleece. Foil is not suitable for this purpose, as liquid can collect under it and there is hardly any air exchange.
The majority of all deciduous ornamental grasses such as elephant grass (Miscanthus), dwarf fountain grass (Pennisetum alopecuroides) or switchgrass (Panicum virgatum) do not require winter protection. The plants themselves provide this. However, only if they are not cut back in the fall, but only in the coming spring shortly before budding. The withered leaves and stalks protect the heart of the plant and ensure that no winter moisture can penetrate. In addition, the leaf stalks look extremely decorative under hoar frost and snow.
Protect wintergreen ornamental grasses from the sun
Unlike deciduous ornamental grasses, where all above-ground plant parts die back in the fall, winter and evergreen grass species such as some sedges (Carex) or woodrushes (Luzula) still present their pretty foliage during the winter months. And that’s exactly what needs to be protected with these ornamental grasses. Most evergreen species truly love shade and are sensitive to sun. When the leaves fall from the trees in the fall, however, they are at the mercy of it and it can quickly come to a sunburn without appropriate protective measures. Wood rushes are best protected with a thick layer of foliage, while evergreen sedges are more likely to enjoy a covering of brushwood. If you live in a snowy region, the layer of snow will suffice as protection from the winter sun.
Wintering tips for ornamental grasses in pots
Ornamental grasses planted in pots have somewhat different winter protection requirements than specimens growing in beds. This is because the small amount of soil that is in the pot freezes through much faster at low temperatures than the soil in the bed. Some species, such as Mexican feathergrass (Stipa tenuissima) or oriental fountain grass (Pennisetum orientale), cannot tolerate this at all. And even ornamental grasses that are absolutely hardy when planted out in the bed, such as Elephant grass or switchgrass, need additional protection in the pot. Therefore, for all ornamental grasses in pots, you should wrap the planters with fleece or a coconut mat. Some foliage on top of the soil will also protect the plants from above.
If overwintering ornamental grasses outdoors, keep larger pots close together after packing them in. The best place to overwinter is in front of a north-facing wall, where the ornamental grasses will be protected from the winter sun. You can also place smaller pots together in a box and fill the spaces in between with straw or leaves. Line the box with some bubble wrap beforehand and the plants are optimally protected. For moisture-sensitive species, however, packing in fleece is not suitable, because with them the roots could rot.
With all ornamental grasses, it is also important that the pot is not placed directly on the cold patio floor. Small feet made of clay or a polystyrene plate can help here. At the same time, clay feet ensure that rainwater can drain off well and that there is no waterlogging, which could freeze at low temperatures.
Wintering ornamental grasses: most important things in a nutshell
- Ornamental grasses that prefer dry soil should not be packed with fleece or foliage. For pampas grass (Cortaderia selloana) and giant cane (Arundo donax), however, tying up and wrapping is necessary.
- Most deciduous ornamental grasses do not require winter protection, as long as you cut them back just before they sprout in the spring.
- Winter and evergreen grasses should be covered with a layer of leaves or brushwood to protect them from the winter sun.
- Ornamental grasses in pots need a place protected from the winter sun to overwinter. Pack the planters with fleece or a coconut mat and cover the soil with foliage.