Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
Apply mulch or compost at a depth no more than 1 to 2 inches, for most perennials. Tender perennials, such as elephant ears, can be protected with a heavier layer of straw or shredded wood mulch (4-6 inches) that can be removed in early spring to allow new growth to emerge.
Cover Plants – Protect plants from all but the hardest freeze (28°F for five hours) by covering them with sheets, towels, blankets, cardboard or a tarp. You can also invert baskets, coolers or any container with a solid bottom over plants. Cover plants before dark to trap warmer air.
I have used old pillow cases, sheets, towels and even cardboard boxes. Just be sure that whatever you use to cover your plant, the cover reaches the ground and traps the warm air inside the canopy. Plastic can be used but it is important to note that you should not let the plastic touch your plants.
The process of trimming back plants is the same for nearly all perennials. Begin by cutting the plant back to 3 to 5 inches above the soil line. Using a sharp pair of pruners or hedge trimmers, cut off all of the foliage and stems. Cut the plants down to within three to five inches of the soil line.
Transplant perennials when the weather is cool, even a little rainy, if possible. Early spring and fall care are best times for transplanting. Then the weather is cooler and the plants are not using as much water. “However, don't move or transplant perennials while they are in bloom,” he says.
2. Perennials and shrubs that are in your zone or one colder can be overwintered in an unheated garage, buried in the ground, or transplanted. 3. Perennials and shrubs in containers will need water through the winter but should not be kept wet.
Container-grown perennials can also be overwintered by placing them in an attached, unheated garage or other structure if you are confident the temperatures can stay consistently between 20 to 45°F. Many unheated structures can vary more widely in temperature than this.
Cutting back of dead or dying top growth is the only maintenance that is needed for winter preparation. Cut the stems down to the ground, or to the basal growth if you are gardening in the warmer hardiness zones. Alternatively, the flower stems can be left to cut back in the spring.
Many gardeners cut back their perennials much too soon. There are nuances specific to certain perennials that dictate whether it is better to cut them back in fall or spring, but the general rule I like to follow is to only cut back perennials that start looking bad in fall.
It's important to cut back foliage in the fall to protect flowering plants from disease and give them a clean start for regrowth as winter starts to turn into spring. However, there are some plants you can keep around through the winter since they benefit wildlife and still offer visual interest for your home.
But when should hostas be cut back? Hostas should be cut back in late fall. Healthy hosta leaves can be left on the plant in early fall to capture much-needed energy, but all leaves should be trimmed off after the first frost to deter slugs and other pests from making your hosta their winter home.
Q: When is the best time to cut back in the fall? A: “When they start to look too ratty for you and before the fresh new growth begins,” says Sarah. For plants that are frost-sensitive, wait until after the plants have gone through several hard frosts to ensure they're dormant before cutting back.
Daylilies are best cut back in autumn, once the leaves have had a full growing season on the plant. While there are some evergreen types of daylilies, most are herbaceous, meaning that the leaves die back in the wintertime and sprout anew in the early spring.
Some perennials benefit largely from regular pruning during the summer growing season, but the most important cleanups are in the fall and the spring. A host of perennials respond best to a tidy spring cleaning and are seemingly rejuvenated from the practice.
If you want to insulate your plants from the cold, don't use only garbage bags to cover them if they're not made from polyethylene. Use a layer of a blanket, towels, cardboard, or any insulating cloth between the plant and the garbage bag. Don't wrap the garbage bag very tightly where it's touching the leaves.
Plastic can be used to protect plants from frost, but it's not the best or most effective material. In fact, the horticultural experts here at Green Impressions actually recommend against it. Plastic materials such as vinyl and traditional camping tarps aren't breathable, causing moisture to get trapped inside.
Large paper bags and cardboard boxes of all sizes can be used to place over plants at night for frost protection. Be sure to remove as soon as the day warms up to let the sunshine in. Smaller paper bags can be placed over ripening fruit or com to protect from frost, birds, or other pests.