If you are lucky, you live in one of those parts of the world where Nature has one last fling before settling down into winter's sleep. In those lucky places, as days shorten and temperatures become crisp, the quiet green palette of summer foliage is transformed into the vivid autumn palette of reds, oranges, golds, and browns before the leaves fall off the trees. On special years, the colors are truly breathtaking.

How does autumn color happen?

For years, scientists have worked to understand the changes that happen to trees and shrubs in the autumn. Although we don't know all the details, we do know enough to explain the basics and help you to enjoy more fully Nature's multicolored autumn farewell. Three factors influence autumn leaf color-leaf pigments, length of night, and weather, but not quite in the way we think. The timing of color change and leaf fall are primarily regulated by the calendar, that is, the increasing length of night. None of the other environmental influences-temperature, rainfall, food-supply, and so on are as unvarying as the steadily increasing length of night during autumn. As days grow shorter, and nights grow longer and cooler, biochemical process in the leaf begin to paint the landscape with Nature's autumn palette.

Where do autumn colors come from?

A color palette needs pigments, and there are three types that are involved in autumn color.

§ Chlorophyll, which gives leaves their basic green color. It is necessary for photosynthesis, the chemical reaction that enables plants to use sunlight to manufacture sugars for their food. Trees in the temperate zones store these sugars for their winter dormant period.

§ Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils, as well as rutabagas, buttercups, and bananas.

§ Anthocyanins, which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums. They are water soluble and appear in the watery liquid of leaf cells.

Both chlorophyll and carotenoids are present in the colorplasts of leaf cells throughout the growing season. Most anthocyanins are produced in the autumn, in response to bright light and excess plant sugars within leaf cells.

During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

Certain colors are characteristic of particular species. Oaks turn red, brown, or russet; hickories, golden bronze; aspen and yellow-poplar, golden yellow; dogwood, purplish red; beech, light tan; and sourwood and black tupelo, crimson. Maples differ species by species-red maple turns brilliant scarlet; sugar maple, orange-red; and black maple, glowing yellow. Striped maple becomes almost colorless. Leaves of some species such as the elms simply shrivel up and fall, exhibiting little color other than drab brown.

The timing of the color change also varies by species. Sourwood in southern forests can become vividly colorful in late summer which all other species are still vigorously green.

Oaks put on their colors long after other species have already shed their leaves. These differences in timing among species seem to be genetically inherited, for a particular species at the same latitude will show the same coloration in the cool temperatures of high mountain elevations at about the same time as it does in warmer lowlands.

How does weather affect autumn color?

The amount and brilliance of the colors that develop in any particular autumn season are related to weather conditions that occur before and during the time the chlorophyll in the leaves is dwindling. Temperature and moisture are the main influences.

A succession of warm, sunny days and cool, crisp but not freezing nights seems to bring about the most spectacular color displays. During these days, lots of sugars are produced in the leaf but the cool nights and the gradual closing of veins going into the leaf prevent these sugars from moving out. These conditions – lots of sugar and lots of light – spur production of the brilliant anthocyanin pigments, which tint reds, purples, and crimson. Because carotenoids are always present in leaves, the yellow and gold colors remain fairly constant from year to year.

The amount of moisture in the soil also affects autumn colors. Like the weather, soil moisture varies greatly from year to year. The countless combinations of these two highly variable factors assure that no two autumns can be exactly alike. A late spring, or a server summer drought, can delay the onset of fall color by a few weeks. A warm period during fall will also lower the intensity of autumn colors. A warm wet spring, favorable summer weather, and warm sunny fall days with cool nights should produce the most brilliant autumn colors.

What triggers leaf fall?

In early autumn, in response to the shortening days and declining intensity of sunlight, leaves begin the process leading up to their fall. The veins that carry fluids into and out of the leaf gradually close off as a layer of cells forms at the base of each leaf. These clogged veins trap sugars in the leaf and promote production of anthocyanins. Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall.

What does all this do for the tree?

Winter is a certainty that all vegetation in the temperate zones must face each year. Perennial plants, including trees, must have some sort of protection to survive freezing temperatures and other harsh wintertime influences. Stems, twigs, and buds are equipped to survive extreme cold so that they can reawaken when spring heralds the start of another growing season. Tender leaf tissues, however, would freeze in winter, so spring heralds the start of another growing season. Tender leaf tissues, however, would freeze in winter, so plants must either toughen up and protect their leaves or dispose of them.

The evergreens-pines, spruces, cedars, firs, and so on are able to survive winter because they have toughened up. Their needle-like or scale-like foliage is covered with a heavy wax coating and the fluid inside their cells contains substances that resist freezing. Thus the foliage of evergreens can safely withstand all but the severest winter conditions, such as those in the Arctic. Evergreen needles survive for some years but eventually fall because of old age.

The leaves of broadleaved plants, on the other hand, are tender and vulnerable to damage. These leaves are typically broad and thin and are not protected by any thick coverings. The fluid in cells of these leaves is usually a thin, watery sap that freezes readily. This means that the cells could not survive winter where temperatures fall below freezing. Tissues unable to over-winter must be sealed off and shed to ensure the plant's continued survival. Thus leaf fall precedes each winter in the temperate zones.

What happens to all those fallen leaves?

Needles and leaves that fall are not wasted. They decompose and restock the soil with nutrients and make up part of the spongy humus layer of the forest floor that absorbs and holds rainfall. Fallen leaves also become food for numerous soil organisms vital to the forest ecosystem.

It is quite easy to see the benefit to the tree of its annual leaf fall, but the advantage to the entire forest is more subtle. It could well be that the forest could no more survive without its annual replenishment from leaves than the individual tree could survive without shedding these leaves. The many beautiful interrelationships in the forest community leave us with myriad fascinating puzzles still to solve.

Where can I see autumn color in the United States?

You can find autumn color in parks and woodlands, in the cities, countryside, and mountains – anywhere you find deciduous broadleaved trees, the ones that drop their leaves in the autumn. Nature's autumn palette is painted on oaks, maples, beeches, sweetgums, yellow poplars, dogwoods, hickories, and others. Your own neighborhood may be planted with special trees that were selected for their autumn color.

New England is rightly famous for the spectacular autumn colors painted on the trees of its mountains and countryside, but the Adirondack, Appalachian, Smoky, and Rocky Mountains are also clad with colorful displays. In the East, we can see the reds, oranges, golds, and bronzes of the mixed deciduous woodlands; in the West, we see the bright yellows of aspen stands and larches contrasting with the dark greens of the evergreen conifers.

Many of the Forest Service's 100 plus scenic byways were planned with autumn color in mind. In 31 states you can drive on over 3,000 miles of scenic byways, and almost every one of them offers a beautiful, colorful drive sometime in the autumn.

When is the best time to see autumn color?

Unfortunately, autumn color is not very predictable, especially in the long term. Half the fun is trying to outguess Nature! But it generally starts in late September in New England and moves southward, reaching the Smoky Mountains by early November. It also appears about this time in the high-elevation mountains of the West. Remember that cooler high elevations will color up before the valleys. The Forest Service's Fall Color Hotline (1-800-354-4595) can provide you with details as the autumn color display progresses.

Source: http://na.fs.fed.us/spfo/pubs/misc/leaves/leaves.htm

Since she retired in 1999, Colleen Graudins has been diving into gardening. For proof, check out the large swimming pool in her Prospect Heights backyard–but watch your step. There's no danger of drowning. You just don't want to trample the breathtaking floral display that has replaced the water.

The pool project, started last fall, is one of many spectacular sights in Graudins' huge yard. Her attention to detail is reflected in the attractive way she blends specimens as well as the fact that most plants are labeled. Touring the garden is both aesthetically pleasing and educational.

"I've always had the gardening bug, but once we retired I finally had the time to do something about it," Graudins says. Prior to that, her job as a project manager in a data processing shop kept her tied up too many hours.

Part of the process was winning turf battles with her husband, Eriks. "He thinks the more grass the better, and I think the less the better," she says.

Graudins laughs when asked how many hours she works on her garden each day. "I'm out there from 5:30 a.m., when I get up with the dog, to whenever," she says. "I pop in and out all day long."

A lover of gardening since childhood, Graudins recalls, "I started my career planting tulips upside-down. My mother knew nothing about gardening, so when I was little I did all the planting."

When she and her husband lived in the city, they dug up the easeway in front of their building and planted a shade garden. "Once we came out to Prospect Heights [20 years ago], my interest was there but when you work and leave at 6 a.m. and you don't get home until 6:30 p.m. there's not a whole lot of gardening you can do."

Graudins admits she's partial to perennials and enjoys the challenge of "growing something that isn't expected here. If it lives, fine, and if it doesn't I've at least enjoyed it for one gardening season." Her experiments have included growing plants from Washington State, where her mother lives, which is Zone 8. "I've come back with arum, which you really don't find here," Graudins says.

Her gardening interests take Graudins beyond the confines of her property. She serves as vice president of the Prospect Heights Garden Club. Last year, Graudins entered the District 9 flower show for the first time. "Out of 13 entries, 13 ribbons," she reports.

Graudins was certified as a Master Gardener last year. "I wanted to help others," she explains. "I've been horticultural chair in the garden club for a couple of years and everyone is always coming to me with questions. I decided to go to the class. I applied, got accepted, and the rest is history!"

Staffing the help desk and participating in "Plant a Row for the Hungry" are a couple of Graudins' Master Gardener activities. She has also presented seed workshops for kids.

Graudins' other main interest is helping Red Door Animal Shelter, a Chicago-based no kill facility. One of her activities with that group is a bit unusual for a gardening enthusiast–fostering bunnies. That's probably why when she finds rabbits chomping on plantings, she moves the plants, rather than the bunnies.

I guess you can say that Colleen Graudins is an all-around nature lover.

- Myrna Petlicki

A big thank you to the Master Gardeners for their help during the summer. Master Gardeners planted and maintained the vegetable garden at Friendship Park Conservatory. They also picked and delivered vegetables to the Des Plaines Food Depository.

Also, the vegetable garden called "Kids on Track" at the Arlington Park Backstretch was a big success with Master Gardeners and children at the track working together to plant, maintain and harvest garden vegetables.

Thank you again for putting forth a great effort, especially in a summer of intense heat.

Pot up rosemary and chives for the indoor garden.

Watch for the annual arrival of the multicolored Asian lady beetle. These are the good guys. They eat scales and aphids. In the fall, they are looking for a place to spend the winter, preferably your home. They will not reproduce indoors. Best control indoors is to vacuum them up.

Select spring-blooming bulbs for planting now. Select bulbs that are firm and free of soft spots.

Plant trees and shrubs now. The hole should be two times the diameter of the root ball, but at the same depth. Keep the plant watered until the soil freezes.

Bring houseplants indoors. Rinse the leaves and check the plants for any signs of insects and disease. Isolate the plants from the rest of your houseplant collection for two to three weeks.

Use a broadleaf weed killer to control Creeping Charlie and dandelions.

Dig up dahlias, caladiums, cannas, gladioli and tuberous begonias before the first hard frost, which usually is around mid-October. Store in vermiculite or peat moss under cool temperatures.

Fertilize the lawn with a controlled-release nitrogen fertilizer. Controlled-release fertilizers release small amounts of fertilizer over a long period of time. This provides more uniform growth. If conditions are dry at the time of application, water the lawn.

- Ron Wolford, Extension Horticulture Educator

This month we're starting a new series spotlighting one of our Master Gardeners' gardens each month. We know how proud you are of your garden so we want to show it off to your fellow Master Gardeners.

This month's garden belongs to Carol Bean. Carol has been working on perfecting her garden for the past 30 years. She has a potting shed located on the side of her home that makes it convenient to the adjacent garden. Lots of hard work has paid off in this truly lovely garden.

If you would like your garden spotlighted in an upcoming issue of Hort Happenings, please contact Eileen at 847-818-2901 or just send in your photo (marked with your name on the back) to Eileen Witt c/o of University of Illinois Extension, Suite 251, Third District Court House, 2121 W. Euclid Ave., Rolling Meadows, IL 60008

The happy gardeners met in Colleen Graudins garden on August 3^rd for lunch and a tour of all her lovely plants. The first plants we couldn't help but notice as we entered her front yard were her very large and beautiful hibiscus. When we entered her back yard, we were overwhelmed by the healthy size of all her plants and her garden is only three years old. It was lovely as was her unusual plantings in a large swimming pool that she had filled with soil. It was a very enjoyable afternoon and we thank Colleen for inviting us all.

Toby Koch has graciously invited us all to her garden for our September 7th Unclub Meeting. The meeting will be at noon time and we are all asked to bring a sandwich and a chair. Toby will supply the drinks and chips. She would appreciate it if some of us would bring along a dessert. After seeing how generous you all were with treats in Colleen's garden, I don't think this will be a problem.

Call 847-818-2901 to RSVP and for directions to Toby's house. Hope to see you all there!

- Carol Bean