WSB Radio Highway Horticulture
Every Saturday morning from 6 to 10 AM join
and Theresa on AM 750 WSB Radio
for a live call-in Lawn and Garden talk show.
Join Walter and Theresa at 8:00 AM for the Cool Plant and 9:30 AM for the Highway Horticulture of the week.
The Philosophy of "Cool Plant" (CP)
Cool plants are plants that I have tried in my garden and was pleased with their
performance. Walter often has many of these plants, too.
They are usually widely available and showy on the dates that we discuss them. We feel that these plants would make
wonderful additions to your garden.
The Philosophy of "Highway Horticulture" (HH)
When Walter and I discuss the plants (sometimes insects or animals)
on "Highway Horticulture," we are discussing things that have been seen
alongside our roads. Some of these plants are native and some are not.
Some are worth cultivating; those marked with an asterisk (*)
are considered non-native invasive weeds and should not be used in the garden.
June 6, 2009
HH: Mimosa Tree* (Albizia julibrissin)
Mimosa trees can now be seen in bloom with their feathery pink flowers. This tree is native to Asia and has escaped
cultivation to invade and disturb a wide range of ecosystems. The trees don't live long due to a fatal wilt disease but
manage to produce copious amounts of seeds. Mimosa is a
Category 1 invasive plant in Georgia.
Despite its attractive flowers, intentionally cultivating this tree is environmentally irresponsible.
May 30, 2009
HH: Spots, Spots & More Spots
The recent abundant rainfall may cause us to label this year as the "Year of the Spots." I'm seeing spots
on all sorts of plants this year from this Indian Hawthorn to oaks, maples, hydrangeas, roses, dogwoods, etc. Many of
these are fungal diseases which won't lead to long term harm but can be treated by pruning to allow more air circulation
and/or sunlight and with the judicial use of fungicides, although control will be difficult this late in the season. I would
also suggest completely replacing the mulch this fall from around severely affected plants. Note: powdery mildew is probably
also going to rampant this summer.
May 23, 2009
HH: Tuberous Vervain* (Verbena rigida)
Along the medians and shoulders of 85, 75 and parts of 285 this non-native verbena can be seen in bloom. Less than 12 inches tall
with bright lavender flowers, it's easy to spot. Unfortunately, this plant is considered an exotic invasive. For the landscape and
roadside plantings, our native groundcover verbena (Verbena canadensis 'Homestead Purple') would make a better choice.
May 16, 2009
HH: Oxeye Daisy* (Chrysanthemum leucanthemum)
Pretty is as pretty does my grandmother used to always say. Such is true for the oxeye daisy. Oxeye Daisy can be seen in bloom now
along roadsides and in disturbed areas. This perennial weed is native to Europe
and has escaped cultivation in all 50 states, including Alaska and Hawaii. It's a banned noxious weed in 5 states and is sure to be
added to others. Consider using Shasta Daisy (C. maximum) as an alternative.
May 9, 2009
HH: Butterweed (Packera glabella)
Fields of yellow are adorning the roadsides of north Georgia as the native butterweed is in bloom.
Although some consider it a weed, I find it to be attractive and fairly well-behaved. The tiny yellow daisy-like flowers are
atop stems 18-24 inches tall.
This plant forms a tidy clump and spreads by seed. Although somewhat short-lived, the seedlings will make up for the loss of older
May 2, 2009
HH: Multiflora Rose* (Rosa multiflora)
Along disturbed roadsides, in fields and along fences throughout Georgia the multiflora rose can be seen blooming
and sprawling over trees and shrubs. The flowers are
5-petaled white to lightly pink and have yellow centers. A native of Asia, multiflora rose is listed as a Category 1 (the worst
category) invasive plant in Georgia which is defined as an "Exotic plant that is a serious problem in Georgia natural areas by
extensively invading native plant communities and displacing native species." After flowering, the plant will produce small
pink to red hips that are eaten by birds. Multiflora rose also spreads by runner and stems which root where they contact the soil.
If you have this plant, please consider removing it and replacing it with a non-invasive rose or another vine.
April 25, 2009
HH: Princess or Empress Tree* (Paulownia tomentosa)
The Empress Tree (aka Royal Paulownia) is a weed tree from China once imported as a landscape tree.
They have huge leaves and stalks of purple flowers that resemble wisteria pointing upwards.
So invasive are these trees, that they are taking over parts of the Blue Ridge Parkway.
Mature trees can produce 20,000 seeds per year. The trunk and limbs tend to be hollow. This tree is best
eliminated from the landscape.
April 18, 2009
HH: Black Locust (Robinia pseudoacacia)
The black locust is a Georgia native tree that reaches 80 feet tall and produces white flowers that hang down in 6-10 inch clusters that resemble
grapes or white wisteria. There is an impressive stand along I-285 on the north side near the junction with I-75. It appears
that some of these were intentionally planted. Although very attractive in bloom, the trees tend to become infested with
leaf miners in summer. It can also aggressively colonize areas and therefore should not be planted outside of its native range
(central and southeastern U.S.).
April 11, 2009
HH: Weedy Wisteria (Wisteria sinensis and Wisteria floribunda)*
As pretty as these flowers may appear, they are death to whatever plants get in their way. The Asiatic Wisterias (sinensis and floribunda)
are among the worst invasive plants in the Southeast.
I cannot stress strongly enough what a bad idea it is to put these in your
landscape. Plant cultivars of our native Wisteria frutescens (ie. Amethyst Falls) which are much better behaved. In fact,
Amethyst Falls Wisteria was a
Georgia Gold Medal winner in 2006.
April 4, 2009
HH: Eastern Tent Caterpillar
Now that the wild and domesticated cherries have begun to sprout leaves, the eastern tent caterpillars have hatched and
are now contained in spider-like webs that can be seen in the crotch at the base of tree branches. Usually, these
caterpillars don't cause significant harm but their webs are unsightly and they do consume the early leaves. Control usually
consists of breaking open the webs thus allowing predators access. These caterpillars will drop from the trees in a few
weeks and disappear. Any damage they cause will be gone by summer.
March 28, 2009
HH: Redbud Trees (Cercis canadensis)
The redbuds look exceptionally handsome this year with their bright lavender flowers as seen at the edges of woods or
planted in landscapes. Soon the heart-shaped leaves will appear followed by bean-like seed pods at the end of the summer.
Redbuds are wonderful trees for smaller landscapes or at the edges of woods.
March 21, 2009
HH: Bradford Pears (Pyrus calleryana 'Bradford')
Although attractive in flower, with deep green leaves to follow that have good fall color, the Bradford Pear is often described as
the worst tree sold in America and for good reason. The flowers smell like week-old fish, the structure of the tree is weak because
all the branches grow from the same location on the trunk, they are short-lived and often get the disease fire blight. The main flaw
with the tree is the structure. As the limbs grow, they press on each other usually resulting in a catastrophic and sudden splitting
in wind or ice. There are much better trees on the market. Bradford Pears are considered trash trees. In my opinion,
all calleryana pear cultivars are not worth of garden space.
Click here to read a strongly worded article.
March 7, 2009
HH: Wild Garlic (Allium vineale) and
Wild Onion (Allium canadense)
While Wild Onion (A. canadense) is native and Wild Garlic (A. vineale) is not, both
are considered weeds, especially when they pop up in the lawn. It can be hard to
identify which is which.
Wild Garlic bulbs tend to have a papery cover which peels away to reveal a white bulb. They also
have a strong garlic scent. Wild Onion has a brown fibrous cover over the bulb. Both are
edible and can be used in the kitchen provided they haven't been treated with any garden
chemicals including herbicides, fungicides or pre-emergents. Control can be achieved by
using such herbicides as Image or products containing 2,4-D. Since they are perennial,
pre-emergents will not stop previous infestations.
February 28, 2009
HH: Henbit* (Lamium amplexicaule).
It's at this time of year that we get a lot of emails and calls about a purple-flowering weed in lawns and gardens.
Henbit is beginning to bloom along roadsides and in landscapes that were not treated with pre-emergents
in the fall. In mass, the flowers make for an attractive roadside display, but this is a
pernicious non-native weed. A winter annual, hanbit will be dead by late spring but will drop many, many seeds.
February 21, 2009
HH: Flowering Quince (Chaenomeles speciosa).
In bloom right now with rosy-pink flowers on thorny, sprawling, tangled, leafless shrubs. These winter-blooming plants are
usually just a few weeks ahead of the forsythia. By summer, the shrub will bear apple-sized yellow fruit that is edible.
February 14, 2009
HH: Okame Cherry (Prunus 'Okame').
Every time I see okame cherries starting to bloom, I feel as though my stomach is getting upset - not because I dislike
these trees, it's because of the color of their flowers. Most
people think or are told that these early blooming pink-purple flowering trees are redbuds (Cercis canadensis), but
the redbuds won't be in bloom for several more weeks. Okame cherries are slightly more pink than redbuds and their flower
color reminds me of Pepto-Bismol, hence that upset stomach feeling.
February 7, 2009
HH: Bronzing of Conifers
||During the winter months, some conifer foliage will become a bronze almost orange color. This is a normal reaction
by some plants to the cold, dry weather. It's commonly seen in junipers, cryptomeria, arborvitae, etc. There is no problem
with the plant and they will again turn green in the spring.
January 31, 2009
HH: Frost-bitten Camellia Flowers
||This poor White by the Gate Camellia japonica had beautiful crisp white flowers only to be hit hard with temperatures
in the teens about ten days ago. To save the plant from wasting energy on these flowers, I will pull
them off this weekend.
January 24, 2009
HH: Red Maples in Bloom
I caught a glimpse of several red maples in bloom this week. While some flowers were red, others that opened before
the intense cold of last week had turned brown. This is a bit early for these trees to bloom. I have noted that those
that were blooming were more in the open where they received full sun.
January 17, 2009
HH: Cold Evergreens (Rhododendron)
When winter temperatures become very cold, many well-adapted and hardy broadleaf evergreen shrubs will wilt or roll their
leaves as protection against the cold. This mountain rhododendron is well-suited to handle temperatures that can be 0 degrees
or colder. Once the temperatures warm up later in the day or a bit of sunshine hits the leaves, they will uncurl without
And for those of you keeping track, my weather station recorded a low on Friday morning of 11.2 degrees.
January 10, 2009
HH: Common Chickweed* (Stellaria media).
Common chickweed is a winter annual weed that is native to Europe. It germinates in the fall through
winter (on warm days), sets seed and dies in the spring. It can be prevented by using a pre-emergent
herbicide in mid September. Once it has germinated, use a
broadleaf weed killer such as Weed-B-Gone to kill it in turf grass areas.
January 3, 2009
HH: Invasive Plants: Japanese Honeysuckle* (Lonicera japonica)
It's the first Saturday of the year which I officially deem as "Invasive Plant Awareness Day" for the Lawn and Garden Show.
This picture shows a native toadshade trillium (Trillium cuneatum) being taken over by the Japanese Honeysuckle vine.
If you don't see a problem with non-native invasive plants, then visit this link:
Copyright © 2009 by Theresa Schrum - All rights reserved
No part of this website may be reproduced without the expressed written permission of Theresa Schrum