The Ornamental Garden in October
It’s October and ornamental gardens everywhere are at their most spectacular. Fall foliage is at its peak and late-blooming perennials are putting on a last glorious show before the arrival of cold weather. There’s a lot to do at this time of year to prepare the garden for winter. But before you get started on those chores, take a look at what’s in bloom and think about where you might add more color in next year’s garden.
WHAT’S IN BLOOM IN OCTOBER?
The first frost can occur in the central part of Virginia as early as mid-October. Unless they are protected from the cold, our precious flowering annuals and perennials can be wiped out with the first chilly night. However, if temperatures remain mild, lots of plants will continue to bloom until late October or early November. Examples include: Chrysanthemums, asters, various salvia species (azurea, angustifolia, or leucantha), grasses, morning glories, zinnias, lantana, globe amaranth, verbena, dahlias, goldenrod (Solidago), caryopteris, annual milkweed (asclepias curassavica), Boltonia asteroides, turtlehead (Chelone), Joe Pye weed (Eupatorium), sneezeweed (Helenium), perennial sunflowers (Helianthus species), tall sedum, Japanese anemone, tall phlox (Phlox paniculata), tickseed (Coreopsis), and monkshood (Aconitum).
WHY LEAVES CHANGE COLOR
As the days shorten and temperatures cool, the vivid colors of autumn transform the landscape. The transformation starts in the cooler, higher elevations and gradually spreads to the warmer, lower-lying valleys. Meanwhile, the veins that transport fluids into and out of leaves gradually close off at the base of each leaf. The clogged veins trap sugars in the leaf, which promotes the production of anthocyanins.
Three types of pigments are involved in autumn color:
- Chlorophyll, which gives leaves their green color, is present in the chloroplasts of leaf cells throughout the entire growing season.
- Carotenoids, which produce yellow, orange and brown colors, are also present in the chloroplasts of leaf cells throughout the growing season but are masked by chlorophyll. Once the leaves stop producing chlorophyll, the carotenoid pigments become visible.
- Anthocyanins, which produce reds, pinks, and purples, are typically not present during the growing season. Anthocyanins are only produced in the fall and are manufactured from the sugars that are trapped in the leaves. They are water soluble and appear in the watery liquid of leaf cells. Their purpose is to protect leaves from being eaten or from getting sunburned.
Many of us are puzzled by the fact that fall colors are vibrant some years and subdued in other years. The intensity of color is influenced by temperature, sunlight, and soil moisture levels before and during the time chlorophyll is dwindling in the leaves. The most brilliant autumn colors are generally produced in years with a warm wet spring, favorable summer weather with adequate rainfall, and warm sunny fall days with crisp, cool nights. See US Department of Agriculture Forest Service publication for more information on Why Leaves Change Color.
Not all pigments are present in the leaves of all trees in the summertime, which is why the foliage of some trees, such as hickory nuts and tulip poplars, turns yellow while the foliage of maples and sour gums turns red. Look at your own property for the colors represented by your plantings and make a list of colors you would like in future gardens. Not enough red? A few suggestions include red maple, sweetgum, blackgum, or scarlet oak trees. Need more orange or yellow? Try growing sugar maple, birch, hickory, ginkgo, sweetgum, yellow poplar, or sassafras trees. Memory is not always reliable, so, while the autumn colors are at their peak, take photos of your garden to study over the winter months.
October is when migratory birds gear up for their long journeys to warmer climates for the winter. Help them out by providing both nectar-rich and seed-bearing plants in your ornamental garden.
Nectar drinkers: Hummingbirds are the best known of the nectar drinking birds. Although your local hummingbird population may be long gone, migrating hummingbirds from other areas may visit your yard looking for a tasty meal on their journey southward. Leave your nectar feeder in place and filled until about 2 weeks after you spot the last hummingbird in your yard in case any late stragglers happen by. For other nectar drinkers, try to include some of the late-blooming perennials and annuals listed at the beginning of this article. Our avian friends will appreciate the meal as they wing their way south.
Seed eaters: As you clean up your flower beds, leave seed bearing plants, such as ornamental grasses, Echinacea or Rudbeckia in place. Not only will the seeds feed migratory birds, they will be a good source of protein for non-migrating birds.
GENERAL FALL TASKS
Plant containers with spring-blooming bulbs for forcing indoors. Fill a pot with good quality, well-draining potting soil. Plant the bulbs twice the depth of their circumference. If you’re planting bulbs of different sizes, plant the large bulbs first, cover them with potting soil, and then plant the smaller bulbs on top. As you cover the bulbs, remember to leave about half an inch of space from the top of the container for ease of watering. Spring bulbs typically need to be chilled for about 3 months at 35°F to 55°F in order to bloom. After you have planted the bulbs, place the container in an unheated basement, storage cellar, cold frame, or garage for that purpose. While the bulbs are chilling, keep the soil moist but not soggy. See Virginia Cooperative Extension Publication HORT-76NP Fooling Mother Nature: Forcing Flower Bulbs for Indoor Bloom for more details on forcing bulbs. University of Missouri Extension Publication G6550 Forcing Bulbs for Indoor Bloom is another good source for information on the subject.
Dig up, clean, and store tender tropical bulbs, such as canna, caladium, dahlia, tuberous begonia, shamrock, and elephant ear (Colocasia). Wait until after the first frost causes the foliage to turn brown. Then, using a shovel or garden fork, carefully dig up the underground tubers or rhizomes (bulbs). To the extent possible, avoid damaging the bulbs. Some tender bulbs may survive in the ground if given protection from the cold. For bulbs that you don’t plan to dig up, such as gladiolas, cut back the foliage and cover the plants with a layer of mulched leaves to help protect them from freezing over winter.
Rake leaves out of flower beds. If left in place, they may harbor pests and possibly certain diseases. Plus, if they mat down, they can prevent moisture from getting to the soil. Collect the leaves in a wire bin or other mesh structure so they can gradually decompose and be used as leaf mold next year. Alternatively, after raking them up, chop them up and redistribute them in flower beds so that they can decompose over winter. Chopped leaves make a great organic mulch.
Start cleaning and storing any breakable lawn ornaments or structures that a hard frost might harm.
Divide peonies. Left to their own devices, peonies seldom need to be divided unless, of course, they have outgrown the space originally planned for them. Another good reason to divide a peony is to propagate new ones. Here’s how to divide a peony easily without doing much harm to its roots:
- Carefully dig around the plant at approximately the drip line. Peony roots are very brittle. The goal is to dig them up with as little breakage as possible. The best way to do that is to avoid digging close to the root ball.
- Gently loosen the soil around the roots until you can lift the plant from the soil.
- Rinse off the roots so that you can see the crown buds.
- Using a sturdy sharp knife, cut the roots back to within 6 inches of the crown. As you divide the roots into the crown, make sure each piece contains a minimum of one bud and preferably three.
- Plant the new divisions so that the crown buds are no more than 2 inches below the soil.
Overwinter some of your favorite annuals rather than allow them to succumb to frost. Either dig them up and pot them if you have room indoors for the full-size plant or take cuttings and root those instead. Geraniums, lantana, begonias, ornamental sweet potato vine, coleus, and New Guinea impatiens are just a few plants that can be overwintered indoors and then planted out again next spring. For best results, place the annuals in a south-facing window. An east-facing window is a good second choice.
Do not prune shrubs and trees in autumn unless you are removing damaged, dead, or diseased limbs. Pruning now may trigger new growth that cannot harden off before winter. The vast majority of woody plants should be pruned in winter when the plant is dormant. But, this rule of thumb does not apply across the board. Check the Virginia Cooperative Extension’s Publication 430-462 Shrub Pruning Calendar, Publication 430-460 Deciduous Tree Pruning Calendar, and Publication 430-461 Evergreen Tree Pruning Calendar for a listing of common woody plants and the best them to prune them.
INSECTS AND OTHER UNINVITED WINTER HOUSE GUESTS
Around mid-October, the adult Lady Beetle (or Ladybugs as they are more commonly known) begins moving out of the garden and into nooks and crannies under tree bark, leaves or other sheltered spots that will afford them protection from winter’s cold weather. As they search for winter lodgings in earnest, they often enter our homes through tiny cracks around windows, doors, attic vents or any other opening available to them. Often, they find shelter within the walls of our homes. VCE Publication ENTO-102NP on the Asian Lady Beetle in Virginia offers tips for keeping them out of your house or dealing with them once they have found their way indoors.
The Brown Marmorated Stink Bug is another insect that often tries to overwinter in your home. Fortunately, the stink bug population seems to have dissipated somewhat over the past year. However, if you see them gathering on the south or west-facing side of your house, chances are very good that they will try to seek entry into your home for the winter. Check out VCE Publication 2902-1100 on Brown Marmorated Stink Bug. It offers advice on how to prevent them from entering your home and how to control them once they get inside.
Insects aren’t the only creatures seeking a warm place to spend the winter. Rodents often look for entry points into the home. To prevent access to your home, seal all potential entry points to keep them out. Leaving the garage door up is an open invitation to a mouse or rat. Make sure there’s no food available to attract rodents. This means storing grass seed or other edible seeds in rodent-proof containers.
INTERESTING FACTS ABOUT “EVIL” PLANTS
In the spirit of Halloween, it’s fun to think about plants that have a reputation for being evil or wicked. Some plants are not necessarily evil or wicked but have bad reputations nonetheless, like crabgrass and kudzu.
Carnivorous plants (Think “Audrey” in “Little Shop of Horrors”): Carnivorous plants thrive in wetland soil that has very little nutrient value. Given such a hostile environment and needing a source of nutrition, they evolved to do something other plants can only dream about – eat the bugs that land on them. Some, like the sundews (Drosera species), are quite ominous looking. Others, such as the pitcher plants (Sarracenia species), are quite beautiful if somewhat odd in appearance. The Venus flytrap (Dionaea muscipula) is the best known of the carnivorous plants.
Poisonous plants: Lots of plants are poisonous – Jimson weed (Datura stramonium), castor beans, and oleander — just to name a few. White Snakeroot (Eupatorium rugosum) is certainly one of the most notorious of this category. As European settlers made inroads into the middle part of the United States, they brought cattle along with them. The cattle ate the snakeroot flowers and humans, in turn, became ill soon after drinking the cow’s milk. This plant is most famous for causing the death of Abraham Lincoln’s mother in 1818.
Here’s a sampling of other poisonous plants:
- Daffodils, tulips and other spring-blooming bulbs, while lovely to look at, contain toxins that are poisonous to both humans and animals. The highest concentration of toxins occurs in the bulb, which can be mistaken for an onion. Ingestion of the bulb can result in a range of symptoms, including dizziness, nausea, vomiting, abdominal pain, diarrhea, convulsions, and coma.
- Buttercups, while also quite charming and lovely in their own way, are toxic to horses and can cause oral and gastrointestinal irritation and blistering. These innocuous-looking little yellow bloomers are just one of many plants toxic to animals. See VCE publication 2907-1398 for information on other poisonous plants of concern to livestock.
- Pokeweed roots, leaves, stalks and berries are poisonous to both humans and animals. Interestingly, tender young pokeweed leaves may be eaten without ill effect in early spring provided they are boiled for about 20 minutes, rinsed in cold water, and then boiled again several times. Don’t try this at home if you don’t know what you are doing. The attractive purple-black berries are the least poisonous part of the plant. Nevertheless, they should not be eaten. Birds, on the other hand, don’t seem to be bothered by the berries and happily chow down on them with no noticeable ill effects.
- Rhubarb stalks are perfectly safe to eat but the leaves contain oxalic acid, which is poisonous to both humans and animals. All parts of the leaves must be trimmed from the stalks prior to consuming them. If the leaves suffer frost damage, they should be removed and discarded because the oxalic acid can migrate into the stalk rendering it unsafe to eat.
Non-poisonous plants with bad reputations:
- Poison Ivy – While this plant is not poisonous itself, it contains a sticky, long-lasting substance called urushiol. This substance causes an itchy, blistering rash after it touches your skin. The rash consists of patches or streaks of raised red blisters, which usually form within 24 to 72 hours of contact and may last up to 3 weeks. Although this plant has a very bad reputation, it does have some merits. Deer can eat its leaves without ill effect and the berries feed approximately 50 species of birds.
- Goldenrod –– For centuries goldenrod (Solidago) was thought to be the cause of fall allergies in humans. But it turns out that ragweed, which spews pollen at the same time goldenrod is in bloom, is the true culprit.
- Black Walnut — Some plants just seem antisocial, like the black walnut tree. This tree is well known for producing a highly toxic allelopathic chemical called juglone. The presence of juglone in the soil deters other plants from growing nearby. Some plants can tolerate it but most can’t. Black walnut isn’t the only tree that’s antisocial. According to VCE Publication 430-021 Black Walnut, other common landscape trees also have allelopathic properties, including sugar maple, tree-of-heaven, hackberries, southern wax myrtle, American sycamore, cottonwood, black cherry, red oak, black locust, sassafras, and American elm.
Plants believed to ward off evil spirits: Betony (Stachys officinalis) – During the Middle Ages, this lovely purple-flowering herbaceous perennial was considered to have properties thought to be protective against harm. It was planted in churchyards and worn in amulets to ward off evil spirits.
Plants that protect against “the evil eye”: Dried dillweed (Anethum graveolens) was worn in a bag over the heart during the Middle Ages as protection against witchcraft and the “evil eye.”
FALL HOUSEPLANT CARE
Now that you’ve moved all your houseplants indoors, keep a close watch for unwanted hitch hikers, such as spiders, spider mites, white fly, scale, and mealy bug. They may not show up for days or even weeks after you’ve moved the plants indoors.
Houseplants may go through a period of adjustment to lower light levels. If they are getting sufficient water but dropping leaves, they may not be getting enough light. If that’s the case, try relocating them to a brighter location.
With the arrival of cooler weather, make sure the air in your home is sufficiently humid to keep your houseplants healthy and happy. A pebble tray beneath your houseplants is a good way to raise the humidity.