Winter Prep

Attribute	Value
Alam Potschke New England Aster	To help asters thrive, water the ground well before the first freeze hits. After the ground freezes, cut the asters back to the soil level and cover them with 2-3 inches of mulch.
Apache Sunset Hummingbird Mint	It's also important to make sure the roots of the plant stay dry in winter, especially if growing in USDA zones 5 or 6. Placing some gravel around the base of the plant as a sort of mulch barrier can help prevent root rot from frozen soil that defrosts slowly in spring.
Astilbe	The flowers can be cut whenever they start to look ragged, or left up for winter interest and cut back in the spring.
Autumn Joy Stonecrop	This plant is hardy to USDA zone 3 and does not need protection even in climates with harsh winters. It will die back, assuming you do not choose to prune it back in the fall, and will bounce back in the spring with fresh foliage and blossoms.
Balloon Flower ‘Sentimental Blue’	Cut back to the base in fall.
Balloon Flower ‘Astra White’	Cut back to the base in fall.
Balmy Beebop Bee Balm	In late fall, cut the bee balm down to just a few inches (5 to 10 cm.) tall. In cold areas, it may die completely to the ground during the winter but will reappear in the spring.
Blackberry Lily	Most gardeners will not find it necessary to give these plants any winter protection against cold, though if you are trying to cheat the standard zone recommendation by growing blackberry lily in zone 4, then a winter layer of mulch may be a good idea. The black seed berries on this plant can be attractive in winter, so many gardeners allow the flower stalks to remain as snows arrive. This will, however, encourage self-seeding in the garden, so if this is not to your liking, then it's best to clip off the flower stalks before they can go to seed.
Bleeding Heart	Bleeding heart will naturally die back during the winter season. But the roots should survive the cold weather, even if the plant appears dead above ground. As the plant depreciates prior to winter, you can cut the stems down to 1 or 2 inches from ground level. Keep watering the soil up until the first frost. At the start of winter, you can protect the roots and help them retain moisture by adding a 2-inch layer of mulch on top of the plant stems. Remove the mulch as the ground thaws in the spring.
Blue Blazes Hummingbird Mint	To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.
Blue Indigo	There is almost no required winterizing routine for these plants. Many people cut off the stems to ground level as winter approaches, but even this can be omitted if you want to leave the seed pods in place for winter interest. And in borderline zones where winters are damp and above freezing, clearing the ground of plant debris is a good idea to keep the soil from being too soggy and possibly causing root rot.
Blue Mouse Ears Hosta	To care for hostas in the fall, keep watering but pull back on fertilizing. The foliage will naturally start to die back. At that point, it's best to cut the plants to the ground to prevent pests or diseases from infesting the depreciating foliage. Hostas in winter are overall hardy and survive just fine. But in cooler climates, it can help to add a layer of dry mulch over the roots to insulate them. Hostas in pots that will remain outdoors for the winter are best buried in the garden up to the rim of their containers and then covered with mulch.
Catmint Walker's Low	Winter or late autumn catmint pruning has many benefits. It will stop catmint flopping over onto neighboring plants, clear out places where pests can overwinter and keep the garden bed looking tidy until new growth emerges in spring. It is best performed after the plant has gone completely dormant, which typically happens after it has been exposed to several hard frosts. Many perennials provide food for wildlife with their seedpods, although not catmint. The seeds are of no use to birds, so the entire plant can be cut back hard, according to the University of Vermont Department of Plant and Soil Science. The University of Maryland Cooperative Extension Service recommends cutting back perennials such as catmint to 2 to 4 inches in height for the winter months. Shear off the entire plant using sturdy pruning shears or hedge trimmers, cutting straight across. Catmint tolerates rough treatment, so don't worry about being gentle when pruning away the stems. Place all dead stems and seed pods in a green waste bin rather than composting them. Rake up the dead, fallen foliage and seed pods from around the plants and discard them, too.
Goldenrod	At the end of the season or in late winter, cut the plant stalks back to a few inches above ground level.
Goldsturm Black Eyed Susan	Plants with seed heads should be left standing over the winter months. Cut back hard in early to mid-spring
Hardy Hibiscus	Mom - “I collect seeds in fall and then when leaves die and look ratty I cut stalks to the ground. They are very late to shown growth in spring.” If you live with mild temperatures year-round, then your hardy hibiscus will thrive throughout the year, too. But if you live in an area where winter temps dip below freezing, you will need to protect your plants. When overwintering hardy hibiscus that's planted in the ground, wrap it in a heavy cloth (burlap) or tarp. The material will need to be able to stand up to freezing, frosty conditions. If your hardy hibiscus is potted outdoors, you can bring it indoors but it will need to stay in temperatures of about 55 degrees Fahrenheit plus about three to four hours of direct full sun a day to survive.the ground. They are very late to shown growth in spring.”
Little Lanterns Dwarf Columbine	Columbines can withstand cold temperatures. At the end of their growing season, remove any wilted columbine foliage and cut columbine stalks to the ground. Flower stalks will regrow next spring, along with any new plants that successfully self-seeded. For extra protection from winter temperatures, scatter a light layer of mulch or decaying leaves around the plant crown.
Karen Azalea	Feeding azaleas should be reduced after midsummer, and watering should also be somewhat reduced in early fall to toughen the plant up for winter. But after a few hard frosts, it's a good idea to water deeply to hydrate the plant, which will help prevent winter burn.
Kudos Coral Hummingbird Mint	To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.
Kudos Gold Agastache	To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.
Kudos Mandarin Agastache	To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.
Orange Daylily	As winter approaches, it is best to leave the foliage in place, allowing it to die off and remain on the ground. This will help to protect and insulate the roots over winter.
Penstemon 'Blackbeard'	Don't bother to cut away any foliage during the winter, as this can help protect the plant. A thick layer of fallen leaves can provide plenty of additional protection.
Rose Campion	There's generally no overwintering maintenance necessary for red campion. Just ensure that your planting site has good drainage. Freezing and thawing soil can become waterlogged if it doesn't drain properly, which can damage or kill the plant's roots.
Rose of Sharon	Rose of Sharon doesn't typically need any special winter care in its growing zones. It ideally should be situated in a spot that's protected from strong, chilling, drying winds. If you live in a cold part of its growing zones, adding a layer of mulch around its roots also can help to insulate the shrub from extreme weather.
Ruby Slippers Dwarf Oakleaf Hydrangea	At the northern end of its hardiness range (zone 5), young plants should be given some winter protection, such as a burlap wrap. If potted, they should be put in a sheltered location, but the plants do not need to come indoors. Clean out all leaves and debris at the root base.
Rudbeckia Maxima “Dumbo Ears”	Rudbeckia fulgida and hybrid 'Goldsturm' (Rudbeckia fulgida var. sullivantii) are also known as black-eyed Susan. They are hardy in USDA zones 3 through 9. Deadheading perennial rudbeckias will also encourage continued blooming. In colder climates, cut the plants back to a few inches tall after they finish blooming. After the first hard frost, cover the plants with a foot of loose mulch, such as straw. In warmer climates where snow is light or rare, you can choose to leave the plants until spring to shelter and feed wildlife, or cut the plants back. Any diseased plants should be removed and placed in the trash. Remove the loose mulch in spring as soon as the weather warms.
Siberian Iris	In late fall or early winter, cut back the foliage to just above the plant crown. Watering should be held back in the winter months to reduce the likelihood of root rot. In colder regions (zones 3 and 4) a layer of mulch applied over the plants after the ground is fully frozen can prevent winter freeze-thaw cycles from heaving the plants upwards out of the ground.
Snowflake Oakleaf Hydrangea	At the northern end of its hardiness range (zone 5), young plants should be given some winter protection, such as a burlap wrap. If potted, they should be put in a sheltered location, but the plants do not need to come indoors. Clean out all leaves and debris at the root base.
Stiff Goldenrod	Goldenrod is a hardy plant up to USDA cold hardiness zone 2 and does not need protection unless grown in containers, in which case it is recommended to winterize the containers to insulate the roots against freezing temperatures. In the garden, the stems can be cut down to a few inches above ground level after frost kills the foliage. Removing the stems, including seed heads, will reduce self-seeding in the garden.
Swamp Milkweed	Swamp milkweed that has been planted in the ground is winter hardy to USDA zone 3 and does not need any protection. When grown in containers, on the other hand, the roots are vulnerable to cold damage in freezing temperatures. Place the container in an insulating silo, or cover it with burlap and bubble wrap.
Tango Hummingbird Mint	To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.
Tiger Lily	Tiger lilies will go dormant over the winter. The bulbs can survive freezing temperatures in the ground, but they'll benefit from a couple inches of mulch over their planting site for insulation. Also, make sure the planting site never becomes waterlogged, as the bulbs need very little water while they're dormant.
Wild Bergamont	As long as you are in zone 3-9, Wild Bergamot will not need special care in winter. But, if you like, you can cut back the dead stalks to the ground in November/December. Personally, I leave my stalks with seed heads up until Spring. This way, birds can eat the seed during the cold winter months. And if any insect larvae are burrowed in the stalks, they will be able to emerge once temperatures warm up in the Spring.
Witch's Moneybags	This plant is hardy to USDA zone 3 and does not need protection even in climates with harsh winters. It will die back, assuming you do not choose to prune it back in the fall, and will bounce back in the spring with fresh foliage and blossoms.