The Ornamental Garden in November
It’s November and there’s a decided chill in the air. Leaves on millions of trees have completed their crash course on how to fall to earth gracefully. Adolescent wild geese, so clumsy and disorderly-looking this summer, have now mastered the art of flying in a perfect V formation. On warmer days, bees, flies and other insects continue to visit the few remaining flowers in search of just one more drop of nectar or pollen. All the signs in the ornamental garden point to the end of the growing season and the beginning of winter dormancy.
GENERAL FALL CLEANUP AND MAINTENANCE TASKS
Before calling it quits in the ornamental garden, a lot of tasks need to be completed this month. Here’s a checklist to help you get started:
- Remove and dispose of plant foliage from roses, irises, daylilies, phlox, peonies, and other plants that are subject to fungal leaf diseases. The cleanup you do now will help prevent fungal diseases in next year’s garden.
- Mulch flower beds after the ground freezes to moderate soil temperatures and prevent frost heaving.
- Leave ornamental grasses standing to provide interest in the winter garden. Wait until late winter or early spring to cut them back.
- Pull weeds while the soil is still soft. Winter may be approaching, but cool-season weeds are oblivious to the cold.
- Monitor moisture levels for any plants that were added to the landscape during the previous growing season. Many plants, particularly newly installed plants, die during their first winter due to lack of moisture. Therefore, in the absence of rain, it’s important to continue watering until the ground freezes.
- Clean and store non-weatherproof objects, such as terra cotta pots, rain gauges, birdbaths, portable trellises, statuary and other garden art.
- Remove, clean, and store all stakes and other plant supports.
- Drain, roll up, and store garden hoses on a warm sunny day when the hoses are pliable and easier to work with. Don’t forget to clean watering wands, quick connects, or irrigation equipment and store in a frost-free location.
- Inventory all pesticides, fungicides, and herbicides to make sure they are well sealed. Store them in a frost-free area to protect them from freezing temperatures.
- Note any needed servicing requirements for your lawn mower, tiller, or other gardening equipment. Try to take care of those now or over the winter months rather than wait until next spring.
- Inspect your garden tools before storing them in your garage or tool shed for the winter. Remove dirt and grime from metal surfaces to prevent the formation of rust. Sharpen any tools that have grown dull from use. Treat wooden handles with a mixture of two parts boiled linseed oil to one part painter thinner or turpentine to prevent the wood from cracking. Finally, organize your tools so that you can easily find them next spring.
ANNUALS, PERENNIALS AND BULBS
Depending on the weather, the November ornamental garden typically looks quite bare, especially toward the end of the month. However, with overnight frost protection and a little cooperation from Mother Nature, it’s possible to have some color in the garden even on the chilliest of late autumn days.
- Include some cold-tolerant perennials and grasses in your landscape for late autumn color, texture and interest. For example, Monkshood (Aconitum napellus), with its stunning, deep blue flowers and handsome foliage, is one of the last perennials to succumb to frost. Just be careful when handling this plant. All parts of it are poisonous.
Consider a cold-tolerant foliage plant, such as Yucca filamentosa ‘Color Guard’ with its variegated cream and green leaves. Bergenia, Sweet Flag, Carex, Foxglove, Dianthus, and Jacob’s Ladder are other plants that have interesting cold-tolerant foliage. Chrysanthemums, of course, will continue to provide plenty of color before finally succumbing to the first hard freeze. A few late-blooming asters, such as lavender-blue ‘October Skies’ may provide pops of color as late as November. The show won’t be as glorious as it was in October, but the bees and other insects will appreciate the blooms nonetheless. TIP: If pinched back in late June or early July, asters will bloom a couple of weeks later in fall.
- Include cold-tolerant annuals,
such as pansies, violas, and snapdragons in the ornamental garden to prolong the color fest as late as possible into autumn. Ornamental kale and cabbage, also known as “flowering” kale and cabbage, are additional good choices that can withstand temperatures as low as 5°F (as long as they have been gradually acclimated to cold weather). Depending on the selection, some are frilly or curly in appearance and all are deeply colorful, displaying hues ranging from cream and deep green to brilliant magenta, purple, and burgundy. They look equally charming as a single specimen in a container or as a mass planting. As you plant them, bury the stems so that the lowest leaves are flush with the surface of the soil.
- Cut back the stems and foliage of established chrysanthemums about three inches above the ground now or, if you prefer, wait until late winter or early spring to cut them back. If the chrysanthemums were planted this fall, they may survive cold weather better if the stems are left in place. The dead foliage will help protect the plant crown during winter. Also make sure the mums are well-watered going into winter.
- Leave tall sedum standing over the winter months. The dried brownish-looking seed heads add plenty of color and texture to the garden in fall and winter. They’re also stunning when covered in frost or ice.
- Plant tulip bulbs in a prepared sunny, well-drained site once the soil cools to about 55°F and night-time temperatures range between 40° and 50°F. Tulips require cool soil so that they don’t send up shoots before the roots are established. They may be planted up until the soil freezes. Plant them deeply (about three times the diameter of the bulb) to help protect them from frost heaving as well as from mice, voles and squirrels. Cover with a layer of mulch about three inches deep. TIP: If you have a deer problem, make a note to protect your tulips from deer browsing the instant the foliage starts to appear next spring. Either use a physical barrier or use a deer repellent.
- Daffodils and tulips are a welcome sight in the springtime, but they never seem to last very long. Prolong the show by planting selections that bloom in early, mid, and late spring. TIP: If you’re planting bulbs in a naturalized (informal) rather than a formal setting, space them a little farther apart than you would normally so that they have ample room to multiply.
TREES AND SHRUBS
Autumn is, of course, the time of year when trees and shrubs take center stage in the ornamental garden. Look around you and note plants that continue to provide interest well into November. Keep in mind that weather conditions have a great deal to do with how long some plants retain their color. In general, Scarlet Oaks, Black Gums, Ginkos and some Crape Myrtles may be relied upon to carry their fall colors into November. Likewise, some shrubs hold their fall colors longer into the month. Oakleaf hydrangeas, Fothergilla, Spicebush (Lindera benzoin), and Spirea thunbergii ‘Ogon’ are examples. Other shrubs, such as winterberries and certain rose selections, provide interest in late autumn with their brightly-colored fruits.
- This is the time of year to fertilize dormant trees and shrubs with a slow-release organic fertilizer so that nutrients will be available to the plants in early spring. Virginia Cooperative Extension (VCE) publication 430-018, ”Fertilizing Landscape Trees and Shrubs,” can provide advice if you’re not sure whether your trees and shrubs need to be fertilized. This publication covers fertilization basics, such as the signs of plant stress and diminished vigor, types of fertilizers, when to apply fertilizer, and how much. When you apply fertilizer, water it into the soil. Without moisture, plants cannot absorb nutrients from fertilizers.
- Thoroughly water both deciduous and evergreen trees and shrubs until the ground freezes. They will thrive better in moist rather than dry soil once the ground is frozen.
- Mulch boxwoods and broad-leaved evergreens before the ground freezes but avoid piling the mulch up against the trunks.
- Protect dormant trees from mouse and vole damage over the winter months. Contrary to what some people think, these diminutive creatures don’t hibernate. In fact, they can do some of their worst damage over the winter months. Voles can do extensive damage to the roots and bark of many woody plants. Several strategies can help mitigate damage from the beasties. Install a physical barrier of hardware cloth or wire mesh trunk guards at the base of vulnerable young trees. Wait until after the first frost to apply mulch at the base of trees and shrubs but be sure the mulch is not touching the trunks. If you were using vole and mole repellents over the summer months, don’t stop just because the weather has turned cold.
- Continue planting deciduous trees and shrubs until the ground freezes. Make sure they are well-watered when cold weather comes.
- If you plan to buy a live Christmas tree and plant it later, dig a planting hole for it now while the ground is still soft. Store any soil that you removed from the planning hole in a spot where it won’t freeze.
Now that houseplants are acclimated to the indoors after their vacation outside this summer, it’s time to focus on their health and well being within your home’s warmer, drier conditions.
- Make sure light levels are adequate for the needs of each houseplant. Give each plant a quarter turn weekly to prevent the plant from leaning toward the light.
- Monitor moisture and humidity levels. The biggest mistake many people make is overwatering their houseplants. With the exception of ferns, which generally prefer evenly moist soil, allow the soil of other houseplants to dry between waterings. Meanwhile, most houseplants prefer relative humidity levels of about 40 to 50% and benefit from being misted two or three times a week. Another way to increase humidity is to place the plants on a tray of moist pebbles. Brown tips on the ends of leaves usually indicate that the humidity is too low.
- Plant paperwhite bulbs in a suitable container such as a small pot or bowl. Fill the container part way with pebbles. Place the bulbs on top of the pebbles. Add a few more pebbles to support the bulbs and water up to the base of the bulbs. Once the flowers start to appear, stake the flower stalks to prevent them from falling over.
- Pot hardy spring bulbs for indoor forcing. For advice on forcing bulbs, see Virginia Cooperative Extension (VCE) Publication HORT-76, “Fooling Mother Nature: Forcing Flower Bulbs for Indoor Bloom.”
- Tropical plants such as Mandevilla, Fuchsia, or Hibiscus may continue to bloom if they are overwintered indoors. Give the plant plenty of bright light, water it when the top inch or two of soil becomes dry and mist the foliage periodically to raise the humidity level. If the plant is too large to overwinter indoors, it may be maintained in a semi-dormant state in a frost-free garage or basement. If you choose this storage method, water the plant sparingly so that the root ball does not dry out.