This newsletter discusses the ongoing drought conditions in Oklahoma and provides tips on gardening during drought. It recommends not applying fertilizer or herbicides when it is extremely hot and dry, as plants are not actively growing and chemicals could volatilize or not be effective. Soil testing is especially important now to determine nutrient needs and prevent runoff. Certain drought-tolerant plants like mint, rosemary, and sedum are faring better in the heat. Green roofs are highlighted as an environmentally friendly option that can help reduce temperatures and energy costs.

1. CLEVELAND
COUNTY
EXTENSION
The Hort Nerd News
HORTICULTURE A U G U S T 2 0 1 2
Drought Continues Again This Summer
INSIDE THIS
It is so hot, I don’t even want to be outside for 5 minutes. I’ve let everything go in my lawn and
ISSUE:
garden, to try and conserve as much well water as possible. I am trying to eek my tomatoes
and landscape plants through with occasional watering, even though I’m drenched with sweat by
What Not To 2
Do In a
the time I finish. I’ve noticed certain plants are weathering the drought better than others.
Drought Slender Mountain mint, rosemary, Arkansas Bluestar, ‘Fireworks’ Gomphrena, lantana, Sedum,
Euphorbia, and Chaste tree are all fairing pretty well, considering the brutal conditions outside.
Bug of the 3
With the gripes about the heat and drought, I did freeze about 6 quarts of tomatoes. So I can’t
Month complain too much. For now, I’m going to enjoy the air conditioning, hope for rain and an un-
seasonably long autumn. Stay cool out there, and drink plenty of water! If you would like to be
Landscape 3 added to the newsletter list, email me at tracey.payton@okstate.edu —Tracey
Design Tip
Hot Plant
Pick
4 Green Roofs a Growing Option
In Oklahoma we are a little behind in the areas of adopting green infrastructure and practices com-
IN THE KNOW pared to other states. However, some of this is out of our control. Hail can limit the use of traditional solar
panels, wind power may be a better option west of I-35, and you need rain to collect rainwater sufficiently.
 Master Gardener Last week I attended an interesting symposium on green roofs sponsored by Oklahoma City. At first this
email questions: topic was a little intimidating, but once I learned a little about the practice it became intriguing. Green roofs
ccmastergarden- are defined as: built surfaces containing a substantial portion that sustains a permanent vegetative layer.
er@yahoo.com These living roofs have numerous environmental benefits to the homeowner and the community.
 Access OSU Fact First, green roofs dissipate heat and reduce energy consumption. This can be a huge factor in ur-
Sheets online at: ban areas and concrete jungles. In addition, green spaces are relaxing, fun to visit, and visually pleasing.
Furthermore, green roofs can lower the internal temperature of structures by as much as 10 degrees Fahren-
osufacts.okstate.edu heit. This can save you money on heating and cooling costs.
Green roofs also have a positive return for businesses and employees. On average, there are fewer
 For upcoming Cleve- occurrences of sickness and sick leave by employees with access to or a view of green roofs and spaces.
land County Horticul- This can equal a more effective and efficient working environment.
ture Events, see our Although initial installation costs per
web page: square foot are higher, green roofs can last
longer than traditional roofs. Some experts
oces.okstate.edu/cleveland/ estimate a successful green roof lasting 2 to 3
horticulture times longer than shingled roofs. In addition
green roofing materials have lower mainte-
 Norman Farm Market
nance costs in the long run.
Every Wednesday and Additional benefits of green roofs
Saturday, 8 am-12 pm. may include: increased building value, fire
prevention, noise blockage, catching storm
 Demonstration Gar-
water runoff, improving air quality, and
den Tours, Saturday, 9
providing wildlife habitat. There really are
am-12 pm.
too many benefits of green roofs that can be
listed or even measured. However, if you are
an employer, building a home, or looking to
update a structure to be greener, you may
think about installing a green roof. A view of the green roof on top of City Hall, Chicago.
http://land8.com/profiles/blogs/chicago-tops-north-america-for

2. Drought Do’s and Don’ts
PAGE 2
Everyone is suffering in the lawn and garden department. Our trees and shrubs
are scorching and dropping leaves. Your lawn is probably brown and brittle, unless you
have a watering system. The Norman area is already experiencing severe drought con-
ditions again this summer. Being a good steward and conserving water is always in
style, but during drought conditions it can be especially important to conserve other
resources.
First, do not apply fertilizer during extreme heat and drought. Now is not the
time to give your lawn, trees, or shrubs a boost. With our lack of soil moisture, fertiliza-
tion will not be beneficial to those plants just trying to survive. In the lawn, I would
suggest you do not fertilize until May 2013. Typically with warm season lawns, like
Zoysia and Bermudagrass, your last month to fertilize is August. Unless we receive sig-
“Do not apply nificant rain before August 31st, fertilization is not recommended. If you have allowed
your lawn to go dormant, as recommended, you may resume watering 1 inch per week
fertilizer during
once temperatures cool off again.
extreme heat and Holding off on fertilizer goes for trees and shrubs, too.
drought.” Summer 2011 was a bad year for plant health, and as a result
most plants grew very little or went into an early dormant peri-
od. Most fertilizer applied before or during last year’s drought
may not have been utilized by the plants. In this case, you may
still have excess fertilizer already present or the unused fertiliz-
er may have ended up in storm water runoff. Dead and
dormant plants use no nutrients. Wait to fertilize until condi-
tions are ideal: when plants are healthy and actively growing.
Second, the only way to know what is really going on in
your soil is to perform a soil test. I’ve touched on this before,
but Lake Thunderbird is on “life support” due to over applica-
tion of nutrients. The future health of Lake Thunderbird de-
pends on the consumer being smart about applying fertilizers.
If you use organic fertilizers or compost, you are not exempt
from soil testing. It has never been more important to be conscious of how and when to
fertilize. Only fertilize based on soil test recommendations.
Lastly, do not apply any herbicides during hot, dry conditions. Most herbicide
labels restrict applications during drought. Some chemicals can volatilize at high tem-
peratures and drift can occur even at low wind speeds, causing irrevocable damage to
desirable plants. Furthermore, herbicides may not be effective on drought affected,
slow growing weeds. You
may be wasting time, money,
and sweat to treat weeds that
won’t respond. In lawns es-
pecially, herbicide sprays can
damage dormant turf as
well. Always read and com-
ply with chemical labels, as
ignoring the label is illegal
and dangerous.
Water restrictions and
drought may become more
common each summer. It is
better to prepare now and
know what to expect, than to
be surprised by continuing
summer warming trends.
THE HORT NERD NEWS

3. HNN AUGUST 2012 PAGE 3
Large Wasps Creating a Buzz
I came to work this morning and noticed a jelly jar on my desk that contained a large wasp. I wasn’t too sur-
prised; it’s not uncommon for my desk to have a plethora of jars and plastic bags on it. I glanced at the jar as I was go-
ing to get my coffee and knew it right away. It’s the time of year for cicada killer wasps to be out and active.
The adult wasp can be intimidating, as they can get as big as 1.5” with black and yellow stripes. The
female cicada killer wasps are capable of inflicting a painful sting, however they are hard to provoke and very docile
(unless they are fighting for their life inside a jelly jar). Mating males may be more aggressive, but are not equipped to
sting. All buzz and no bite. Cicada killers excavate a hole in the ground, so U-shaped mounds of dirt may be associated
with their burrows. These wasps are very common this time of year and may be more likely in areas where the soil is
bare, like between plants in flower beds and planters. They can also be found in the lawn, but are more uncommon in
healthy, thick turf. Cicada killers don’t feed on plants, the adults feed on nectar and the larvae feed on paralyzed cica-
das. Unlike some wasps and bees, these insects tend to be solitary and have a better attitude.
Cicada killer wasps overwinter in the soil and begin emerging as adults in June. For several weeks prior to cap-
turing cicadas, the adult female feeds on the nectar of nearby flowers, mates with a male, and digs burrows. These
ground nests tend to be vertical or somewhat angled, ½” wide and 6-10” deep. Perpendicular to the main tunnel, the
wasp will dig broad oval cells. Once the cells have been dug, the
search for prey begins.
The female adult cicada killer begins searching tree trunks
and lower limbs in search of noisy cicadas (some people incorrectly
call them locusts). Once the prey is found, the wasp stings the vic-
tim and turns it on its back, straddles it, and drags or glides with it
back to the burrow. Each cell contains at least one paralyzed cicada
where the wasp has laid an egg, and then the cell is sealed. When
the wasp egg hatches two to three days later, the legless larva will
feed on the insides of the cicada for 4-10 days, until only the shell is
left. In fall, the larva spins a silken cocoon to overwinter. Then the
cycle begins again. There is only one generation of the cicada killer
wasp per year.
If you have a very large population, say 10 or more in an
area with young children, treatment may be warranted. The best
means of control is a light dusting around the entry of the nest.
Products containing the active ingredient carbaryl, found in Sevin
Dust, are recommended. Be aware that this is a broad spectrum
insecticide and will kill most anything that comes into contact with
the dust. Wasp and hornet sprays may also work, but you have to
contact the insect with the spray, increasing the chances of aggra-
vating the wasp. I typically don’t recommend treating these insects
unless you absolutely have to. These wasps are considered benefi-
cial, and are also pollinators. Cicada killer wasps should be treated
with the same respect as bees, so consider using them as a teaching tool.
Landscape Design Tip
Corners in the landscape can be an eye sore and detract from the flow of
plant material. Soften a sharp corner by incorporating a small tree or shrub,
like a crape myrtle or chaste tree if the space gets full sun. Also use annuals,
perennials, or bulbs under or around the shrub to add interest. Keep scale of
homes, fences, or retaining walls in mind and know the mature height of
plants. Do not use grasses or needle leaved evergreens near the home, as
they can become a fire hazard.
Photo courtesy of http://ccmgatx.org/design/hoadesignplans.asp

4. The Oklahoma Cooperative Extension Service,
a division of Oklahoma State University, pro-
vides a link for the public to Oklahoma State
University research, tools, and practical infor-
mation. Through our 77 county based offices in
Cleveland County Cooperative
Oklahoma, we strive to provide a resource for
Extension Service
better growing, living, farming, communities,
health, and youth education programs.
At the Cleveland County Fairgrounds
601 E Robinson
Norman, OK 73026
The Oklahoma Cooperative Extension Service offers
Phone: 405-321-4774 its programs to all eligible persons regardless of
Fax: 405-360-0319 race, color, national origin, religion, sex, age,
E-mail: tracey.payton@okstate.edu disability, or status as a veteran, and is an equal
opportunity employer.
Bringing the University to You.
See our website: www.
oces.okstate.edu/cleveland/horticulture
Hot Pick Plant
This plant makes me happy. Every
day when I pull into my driveway, I
see these happy little pink blooms
welcoming me home. The blooms
are still hanging on, despite the heat and wind.
They aren’t pristine, mind you, but to see the
splash of pink amid brown and scorched is a nice
sight. Gomphrena will get several feet high and
wide, so put it behind a shorter plant and give it
a little room to expand. (Mine is situated behind
a blue-green euphorbia border.) I typically don’t
Photos courtesy of greensparrowgardens.com and Bustani Plant Farm
believe in annuals, but this is one of only a hand-
ful that make my list. It’s tough, pretty, interest- Fireworks Globe Amaranth
ing, and pink! What more could you want? Gomphrena ‘Fireworks’