Fall Color in Your GardenFall Color in Your Garden “Autumn is a second spring when every leaf is a flower.” – Albert Camus
Fall colors include foliage, stems, fruits and still a few flowers. There are beautiful perennials and annuals which will continue to give us colorful blooms for many more weeks. Some bulbs, like autumn crocus, are fall blooming. Fall foliage colors are plants’ displays that begin with the ending of summer. In autumn the sun drops lower in the sky every day. Traveling through more atmosphere, red, orange and yellow are more prominent components of the sunlight we see. We’re surrounded by tones of yellow, orange, pink, peach, rust and red from the plants as well. Plants like dogwood and river birch produce nearly purple leaves each fall. The Biology of Fall Color Chlorophyll is the green of plants and it is the main pigment responsible for photosynthesis (light energy and CO2 to chemical energy). As days shorten, nights cool and plants dry, photosynthesis decreases and spent chlorophyll is not replaced. As the green of chlorophyll fades, other pigments that were previously masked begin to show. Carotinoids, tannins and anthocyanins are some of the other major pigments found in deciduous leaves. All leaves contain carotenoids that help transfer light energy to chlorophyll. There is a reason so many of our high-elevation plants have a golden fall color. Carotenoids help protect chlorophyll from high-elevation overexposure to light. Beta-Carotene is one of the most common carotenoids present in most leaves. Beta-Carotene absorbs blue and green light and reflects yellow and red light, giving leaves their orange hues. Carotenoids are more durable than chlorophyll but less efficient at light gathering. They help by protecting the fragile and more efficient chlorophylls. Carotenoids are bound in the chlorophyll containment areas of each leaf cell. Flavonols, a part of the flavonoid protein family, is always present in leaves. Though present, it’s golden colors remain unseen until Chlorophyll production slows. Anthocyanins are water soluble (“watercolor”) pigments dissolved inside leaf cells. Anthocyanins produce red, pink, purple and blue colors. They are the pigments found in purple-leaved trees & shrubs. The early red color of new growth in many high-elevation plants is from anthocyanin; it blocks some UV light and the sugars act as anti-freeze. Anthocyanin production increases as chlorophyll production declines. Anthocyanins make cherries, cranberries, and beets red and make grapes and blueberries blue. The inside of cells become more acidic with age and lower pH makes anthocyanin colors more red. Early season cell contents are more basic and will generate more blue colors from the same anthocyanins. Iron and aluminum in leaf cells also modify colors. Anthocyanins are used as pH indicators because their color changes with pH; they are pink in acidic solutions (pH < 7), purple in neutral solutions (pH ~ 7), greenish-yellow in alkaline solutions (pH > 7). In cells, anthocyanins are “blue blockers” and filter-out damaging ultra-violet (UV) light. Anthocyanins are fused into sugar molecules within cells and sugar supplies are required for anthocyanin production and display. As leaf sugars are generated for transport out of the leaf (for storage in roots and stems), low temperatures and a developing abscission layer slow sugar movement and keep more in the aging leaves. In plants with red fall colors, more sunlight usually produces better colors. Vine maple, big-tooth maple, mountain ash, serviceberry and red-twig dogwood all grow well in moderate shade and still give us intense orange-red through purple fall colors. Orange leaves are a combination of anthocyanins and carotenoids. When chlorophyll, carotenoids and anthocyanin are gone and the leaf turns brown, tannin is responsible. Tannin gives us the beige, tan and brown of autumn. Tannin is contained in all leaves in varying amounts. Some trees such as Bur Oak and many grasses have high concentrations of tannin and their leaves turn amber in fall. Causes of colors: While the genetics of plants determine which colors the plant can display, there are also other factors. Shortening day-length, cold nights and drought are all factors. We have no control over the first two but we can often affect the third. Drier conditions in late summer can reduce the production of chlorophyll and hasten the transition into winter acclimatization. Ideal conditions for the best fall colors start with a couple of September frosts followed by warm sunny autumn days and cool (barely freezing) nights for a long “Indian Summer”. Without hard frosts some photosynthesis can continue to produce sugars that are used to make anthocyanins. Weather can also ruin fall colors. Hard frosts can turn leaves brown while cloudy or rainy days inhibit the color because of the lack of light and warmth. A more acidic soil may make redder leaves and a more alkaline soil makes more purplish leaves in some species. To acidify soil, add cottonseed or neemseed meal or a little iron sulfate. To raise the pH of soil and decrease acidity, add lime or wood ashes. In order to survive winter temperatures, trees slowly close off the tubes that carry water and nutrients to and from the leaves with an abscission layer of cells that form at the base of the leaf stem, protecting the “limbs and body” of the tree. When the abscission layer is complete, water and nutrients no longer flow and the leaf slowly dies and, weekend at the stem, falls gently away. What you can do: Begin cutting back on watering in early September to let plants know it is time to prepare for winter. Plants need to “shutter” up top to avoid winter damage. It is not bad to see your plants occasionally wilt a little but do not let them dry out completely. After fall color begins in earnest, keep-up the watering so the fall root growth can be maximized. (It is best to keep newly planted trees, shrubs and perennials moist in fall to maximize new root production.) Pruning: If leaves are still green, into mid-September, woody plants should have enough time to seal the cuts before the cold / dry winter. Major pruning is best done late winter to early spring with hedging or heading-back during the growing season. Fall pruning, after dormancy, is not recommended unless a branch is in imminent danger of being ripped off by snow (or if a plant is excessively vigorous). Fall pruning leaves open wounds and removes stored energy. Fall Color to see: Pear on High st. corner of Spring. Lilac (actually has purple fall color some years) corner of Church and Donner Pass Rd. – (don’t prune lilacs after June), Tansy, Nova-belgii (New York) aster – (add calcium and pinch in June to help stems stand-up). See Juniper, Arctostapylos, Oregon grape, Thimbleberry at Gray’s cabin. The C.B.White House has a red oak. The Eaton House has several Bigtooth Maples. The Library has Vine Maple, Spiraea and Crabapple. The Hospital MOB has a Golden Currant. The Post Office (1984) has Maples: (Red, Norway, Big-tooth, Amur), Serviceberry, Nine-bark, Red-twig Dogwood, Golden currant, Sumac, Russian olive. Alibi has Hawthorne, and Mt. Ash-tree to shrub. Brickletown has cranberry bushes, oak, Bechtel / Brandywine crabapples, apples and more. The sheriff’s office, Truckee Physical Therapy and, of course, Villager Nursery, have some excellent examples of fall colors.
Plants for Fall Color
And many, many more!!!! “I trust in nature for the stable laws of beauty and utility. Spring shall plant and autumn garner to the end of time.” – Robert Browning | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||