Late fall is the best time to winterize perennial plants. A hard frost can be the signal to prep the beds for winter. If below-freezing temperatures are forecasted overnight, or you wake up to frost on the ground, it's likely a good idea to winterize your perennials within the next few weeks.
Cutting back perennials in the fall is not only a great way to keep flowerbeds looking neat and tidy through winter, but it also aids greatly in keeping plants vibrant and blooming the following year. Removing spent foliage and blooms helps a plant focus on recharging it's roots and resources.
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.
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.
A good rule of thumb is that if the plant blooms on new growth, it can be pruned in winter, before the new season's growth begins and after the final bloom of the year. Be careful with spring-blooming shrubs—those usually can't be pruned in winter without damaging the flower buds and ruining the blooming season.
It's common to think that everything should be chopped down to the ground in the fall, but some perennials actually need their foliage to protect new shoots through the winter. Other varieties offer up important habitat for local wildlife and some perennials provide height and interest through the winter months.
For instance, you could cover the plant with an old comforter and then a sheet of plastic. No matter what you use, it is important to uncover the plant after the threat of frost has passed so the plant can get light as well as to prevent heat build up under the canopy once the sun comes out.
Once temperatures drop below 40°F, you may want to start covering your plants with a frost blanket depending on what you're growing, which we'll get into in just a bit. Freeze – A freeze is when the air temperature is 32°F or below.
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.
Add a Layer of Mulch
Mulch is a garden miracle-worker any time of year and an important part of winter care. Think of mulch like a blanket protecting the garden during the winter months. A common winter problem is heaving or uplift of soils caused by freeze-thaw cycles.
Cover Up the Garden Beds
Although many of us end up adding it in the spring, you really want to add compost in late autumn in order to let the soil soak up those nutrients over the winter. Add a couple inches of compost or manure on top of your beds any time before the ground freezes.
The answer is, yes, depending on what plants you have. If you live in an area that gets snowfall during the winter months, many experts recommend covering your raised beds with a thick layer of mulch or plastic to protect your sensitive plants from potential damage.
Never prune too early in the winter, as incisions can dry out if the temperature drops well below freezing. When pruning, first prune out dead and diseased branches, especially those caused by the winter's snow and ice. Unwanted lower branches on all evergreen shrubs and trees should also be removed in late winter.
"As soon as trees and shrubs go into dormancy, pruning can begin," he said. "And you can prune up to the time when buds begin to plump up." From mid-November to mid-March, you can shape and thin your deciduous plants in preparation for the spring season ahead.
With adequate rainfall, established plant species appropriate for our climate typically need little to no supplemental irrigation during the winter. Exceptions to this rule include newly planted trees and shrubs, plants in containers, and periods of unusually dry winter weather.
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.
Most trees should be pruned during the late dormant season (February through March). February through March is generally regarded as the best time to prune most deciduous trees.
With reduced sunlight and dry air from indoor heating, winter isn't a time when your plants will thrive, but, with the right care, they can certainly survive. “Less sunlight typically sparks a plant's natural dormancy,” says Casey Godlove, creative director at PlantShed.
To prevent the disease from returning the following year, we suggest cutting the plants back in the fall and removing any debris – no matter the variety! It will give your plants a clean start next season. *Destroy any foliage with symptoms of powdery mildew and disinfect pruners before trimming other plants.