Gardeners know that fall is the best time to do most of their yard work. It is time to plant, time to aerate the lawn and also time to winterize the garden. Most plants can be cut back to the ground to let rest for winter while others should be left alone to prevent rot and winter damage. Some plants are a good source of seeds for the birds and some plants seed around the garden too. This article is a quick guide of suggestions on how to treat some herbaceous plants before and after frost has set in.
Plants that should not be cut back in fall are woody perennials. These are plants that form a woody stem, but more than likely resprout new shoots close to or at the base of the plant the following spring. A few examples of this are hibiscus, lantana, flowering maples and Mexican sages. It is better to wait until late winter to cut their old stems down because they tend to stay green through the fall and early winter. If the stems are still green, they can still take on moisture. If you were to cut the stems while they are green, the cut portion will absorb moisture. If that moisture happens to freeze, stems and roots may rot. The best time to cut back these plants is late February or early March right before the weather turns warmer and right before the new growth appears.
Examples of plants that have attractive flower heads to be enjoyed by both humans and the birds are mostly plants in the daisy family. Gold Finches especially love the black eyed Susan and hardy sunflowers throughout the winter months. But other plants such as asters, relatives of the mint family and hardy mums can be cut back to the ground in fall as their stems, flowers and leaves tend to turn brown and often become unsightly. Also, these plants have the tendency to seed around and pop up in other areas of the garden. You can prevent that by removing the stems just after flowering. Lastly, ornamental grasses are hit or miss, ornamentally speaking. Some are attractive during the winter months, especially some that are upright such as switch grasses or Panicums. Others tend to flop and can be cut back to about 6 inches above the ground before winter. If you choose to leave your grasses through the winter months, cut sometime in late February before new growth appears. It is always safe to cut back ornamental grasses to 6 inches above the ground.
In the shade garden, you may want to remove some foliage once frost has set in. There are a lot of plants that can carpet the ground and that can be showy in winter. If you have Italian arums, cyclamens or early spring ephemerals, be sure to remove old hosta leaves or ferns to keep your winter performers free of excess plant debris for viewing. It is easy for spent hosta leaves to cover precious cyclamens. Ferns tend to flop over and become unsightly too. Plants that are evergreen in the shade garden or plants that perform well in winter are the hellebores, sacred lilies and hardy asarum. Occasionally, old leaves can be removed from these plants, but there really is no need to cut these plants back to the ground. I recommend going through the shade garden once every 3-4 years and perform a mass cleaning of evergreen perennials.
Bulbous plants have the ability to store energy and enough moisture to keep them viable in a dormant state throughout the winter. Gardeners who highlight their gardens often do with summer performers such as elephant ears, dahlias and gladiolus. If you are unsure of their hardiness, bulbous plants can be dry stored in a dark cool environment such as a basement, crawl space or garage. Once frost desiccates the foliage, remove the leaves and stems, dig up bulbs or tubers and let them air dry for a couple of hours. Remember to remove any wet soils too. Place dry bulbs in crates, paper bags or plastic pots and store them for the winter months. There really is no need to water or check on them as long as they are kept cool.
Some of these bulbs can be left in the garden during the winter months. Hardy elephant ears and angel’s trumpets may benefit from a layer of leaves to keep their roots warmer during stubborn cold winters. Wrap a cage or some structure 12 inches around the stems of the plants at least 18 inches high. Stuff the inside of the cage with shredded leaves to act as a blanket for plant roots.
When highlighting the garden with summer annuals, starting new with stem cuttings may be the way to go. Coleus are some of the easiest plants to root. Before frost, simply take 6 inch cuttings, remove the bottom row of leaves and place the stems in a cup of water. Make sure you have some leaves, as leafless stems will rot. Place the cups of rooting stems in a bright window until you see a substantial root formation. Once the plants root, the cuttings will need to be placed in potting soils and kept misted but not wet until spring.
Lastly, be sure to visit public gardens that are always open for viewing. Some of the best ways to know what should be cut and what should be left behind can be seen by watching professionals perform seasonal tasks. Not only are the garden spaces a good example of what performs well, but also, as a guide on how to take care of the gardens themselves.