|
 Each fall as the days shorten our deciduous trees
and shrubs begin this transformation. The plants produce less of the
chlorophyll that gives leaves their normal green color. The existing
chlorophyll starts breaking down, revealing the underlying pigments
of yellow, red or orange.
The carotenoid and xanthophyll pigments assist the chlorophyll in
capturing light and producing sugar during the growing season. The
beta-carotene contributes to the orange and orange-yellow fall
color. Lutein is the most prominent xanthophyll pigment producing
bright yellow fall color. There are over 80 different pigments in
these two categories contributing to the variations in fall color.
The tanins in leaves contribute to the golden and brown fall colors.
These are thought to discourage animals and insect pests from
feeding on the leaves and help defend the plants against disease
organisms.
At the same time, these plants begin to create an abscission layer
between the leaf and stem. This barrier prevents the sugars produced
in the leaves from moving down into the roots for storage.
Purple and red fall color, from the anthocyanin foliar pigments, is
produced when sugars build up and are trapped in the leaves. This
results in brilliant red and purplish-red fall color. Some of these
pigments are present during the growing season and can be seen in
new growth and mature leaves of some plants. These add color to the
garden, help protect the plant cells from high light damage, and may
discourage animals and insects from dining on the plants.
Warm, sunny days followed by cool nights without a hard frost mean
more sugar and better red, orange, and purple fall color. Sufficient
soil moisture helps keep the leaf color bright for a longer period
of time. Leaf color fades, turns brown and leaves drop from the tree
more quickly during dry fall weather.
Fall foliage is not restricted to deciduous trees and shrubs. The
leaves of many of our favorite perennials also turn brilliant colors
in the fall.
[to top of second column] |
Solomon’s seal and hosta leaves turn a beautiful
yellow, echoing the fall flowers of witchhazel and yellow leaves of
ginkgo and quaking aspen. The delicate heart-shaped leaves of
barrenwort, botanically known as Epimedium, turn red in fall. Some
of the leaves drop in fall like most trees and shrubs. Others will
persist through winter and drop as new leaves and flowers appear in
spring.
Perennial geranium and Bergenia leaves turn
reddish-purple in fall. Both will persist, adding color to the
winter and early spring garden.
Brighten up the fall landscape with the fine texture and amber-gold
fall foliage of Angelina sedum and willow amsonia.
The fluffy white seed heads of our native little bluestem complement
the coppery-red fall color that persists throughout the winter.
Genetics determine the color each plant tends to produce in fall,
while weather and the plant’s health influence if and how intensely
the color will be expressed. Consider fall color when adding plants
to the landscape. Then provide proper care to keep them healthy and
looking their best throughout the year.
Melinda Myers is the author of over 20 gardening books, including
The Midwest Gardener’s Handbook and Small Space Gardening. She hosts
The Great Courses “How to Grow Anything” DVD series and the
nationally-syndicated Melinda’s Garden Moment TV & radio program.
Myers is a columnist and contributing editor for Birds & Blooms
magazine. Her web site is www.MelindaMyers.com.
[Photo credit: Melinda Myers, LLC]
 |
