August 2014 / Volume 90      

In This Issue
August Lawn and Garden Tips
The Fall Plant Sale is Here!
TLC for Turf Grass, Trees and Shrubs
Blossom End Rot
Will the Weather Keep This Up?
Ask A Master Gardener...Nutgrass

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

82 degrees 


Rainfall total last 30 days:  

4.32 inches


4 Ways to Contact Us
Email us at:

See our website at: 

Call: 918-746-3701 from 9-4, M-F 
Visit us at 4116 E. 15th Street, Gate 6 at the Fairgrounds

Whether you call or bring samples of plants to the office, trained Master Gardeners will answer your gardening questions with science-based information.
Need More

Click on any of the links below:


All about butterfly gardening in Tulsa County 

How to Take a Soil Test

How to collect a good sample of soil from your lawn or garden and get it tested at the OSU lab.
Understanding Your Soil Test Results
Once you have collected your soil test and gotten the results back, now what? Find out here. 
How to Plant a Tree in Oklahoma Soil
Show and tell.
Cool Season Lawn Care (Fescue)
12-month maintenance calendar.
Warm-Season Lawn Care (Bermuda)
Ditto above.
Trees for Tulsa
A list of recommended trees with descriptions.
A list of over 60, by size and color.
Demonstration Garden
Visit our demonstration garden on 
15th Street, open 7 days a week.  
Oklahoma Proven Plants
State horticulturists, nurseries and growers pick favorite plants, shrubs and trees for use in the Oklahoma landscape. See the winners for this year and years past.
Current and historical source of rainfall, air temperatures, soil temps and much more. Click on Bixby station.  

Back Issues  

Past issues of our eNewsletters can be read and downloaded.

Become a Master Gardener

Classes start in September each year. Register at our office on 15th Street for more information.

Oklahoma State University, in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, gender, age, religion, disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, financial aid, and educational services.

August Lawn and Garden Tips     
  • August is a good month to start your fall vegetable garden. Bush beans, cucumbers, and summer squash can be replanted for another crop. Beets, broccoli, carrots, potatoes, lettuce, and other cool-season crops can also be planted at this time. (HLA-6009)
  • Soak vegetable seed overnight prior to planting.  Once planted, cover them with compost to avoid soil crusting.  Mulch to keep planting bed moist and provide shade during initial establishment.  Monitor and control insect pests that prevent a good start of plants in your fall garden.
  • Continue protective insect applications on the fruit orchard.  A good spray schedule is often abandoned too early.  Follow directions on last application prior to harvest. (EPP-7319).
  • Water compost during extremely dry periods so that it remains active.  Turn the pile to generate heat throughout for proper sterilization.
    Always follow directions on both synthetic and natural pesticide products.
    Watch for high populations of caterpillars, aphids, spider mites, thrips, scales and other insects on plant material in the garden and landscape and treat as needed. (EPP-7306).
    Water all plants thoroughly unless rainfall has been adequate.  It is better to water more in depth, less often and early in the morning.
  • Grassy winter weeds like Poa annua, better known as annual bluegrass, can be prevented with a preemergence herbicide application in late August. Water in the product after application. (HLA-6420).
  • Areas of turf with large brown spots should be checked for high numbers of grubs. Mid-to-late August is the best time to control heavy white grub infestations in the lawn. Apply appropriate insecticide if white grubs are a problem. Water product into soil. (EPP-7306).
  • Tall fescue should be mowed at 3 inches during the hot summer and up to 3 inches if it grows under heavier shade. (HLA-6420).
  • For areas being converted to tall fescue this fall, begin spraying out bermudagrass with a product containing glyphosate in early August. (HLA-6419).
  • Irrigated warm-season lawns can be fertilized once again; apply 0.5 lb N/1,000 sq ft in early to mid-August.
  • Brown patch of cool-season grasses can be a problem. (HLA-6420).
  • Towards the end of the month, divide and replant spring-blooming perennials like iris, peonies, and daylilies if needed.
  • Discontinue deadheading roses by mid-August to help initiate winter hardiness.
  • Watch for second generation of fall webworm in late August/early September. Remove webs that enclose branches and destroy; or spray with good penetration with an appropriate insecticide.

The Fall Plant Sale is Here!   
The Fall Plant Sale is now in progress. A selection of pansies and panolas is available to order through September 19, 2014. We have added to our color selection from last year and hope that everyone can find the right mix for their fall and early spring plantings. These plants are usually hardy through the month of May. During the winter, with some sunshine and a little warmth, they will bloom and provide color in an otherwise dormant flower bed. Those of you who have shopped our Spring Plant Sale know the quality of the plants we sell, and now you can purchase the same high-quality plants for fall. The plants will be delivered directly from the nursery on the day of pick up.

These plants are being offered through our online shopping cart only. You may click here to access the catalog and view the selection of plants we are offering.

Proceeds from our sale help fund the many educational services and programs provided by the Master Gardeners in Tulsa County. There is never a charge for our services, and this sale is one way that is made possible.

Orders must be placed by September 19, 2014. Plants will be available for pick up on Wednesday, October 8, from 10 am to 3 pm at the OSU Extension Center, 4116 East 15 Street, Gate 6. Plants not picked up by 3:00 will be considered a donation to the Tulsa Master Gardeners. (Please note: this address is different from the Spring Plant Sale pick up location.)

TLC for Turf Grass, Trees and Shrubs  
The transition from summer to fall marks the best time to plant trees and many shrubs, as well as cool-season grasses (rye, fescue, bluegrass). Late winter into early spring (March, April) are also acceptable times to plant, but this allows less time for root systems to develop before the growing season gets in full swing. As Oklahoma summers go, 2014 has been one of the more pleasant ones in history, but your landscape still needs a bit of TLC to get through the final days of summer, and to get ready for the winter ahead.

When it comes to watering, most of us know that turf grass needs about one inch of water per week in order to survive (even more to thrive in dry weather). But, did you know that plants, especially new ones, sometimes need more water and trees, especially in their first year of growth, need even more water in order for their roots to grow strong enough to make it through a potentially hot, dry summer or a very cold, dry winter (or both). Natural rainfall is usually not adequate to provide the needed moisture. Newly planted shrubs and trees should be watered well at the time of planting. Then, young plantings need the equivalent of one to two inches of rain per week. And for trees, new plantings need a deep watering two or three times per week in hot, dry, windy conditions because their root systems cannot take up the amount of water needed to replenish the water lost through leaves (called transpiration). Water slowly so that the roots have time to absorb the water that is percolating into the ground. If you have several young shrubs and trees, a trickle irrigation system would be a wise choice. Not only does it minimize wasted water by directing it straight to the root zone but it minimizes certain diseases (mold, mildew, etc.) that can be caused by water being sprayed onto and remaining too long on leaves. Finally, be cautious not to overwater or the amount of oxygen in the soil could be lowered to a level that might damage roots.

As for fertilizing, warm season grasses (Bermuda, zoysia, buffalograss) need to be fertilized during their growing season. August is about the latest in the season you want to fertilize any warm season turfgrass. Bermuda grass needs about one pound of nitrogen per 1000 square feet per month. This translates to a total of about five pounds of nitrogen per 1000 square feet per season. Zoysia requires nitrogen as well but a bit less, around three pounds of nitrogen per 1000 square feet per season. Cool season grasses, such as fescue and rye, need to be fertilized just before their growing season starts, in either October or November, then again at the end of their growing season in March or April. Potassium and phosphorus should not be applied unless a soil test indicates it is needed. This is because these nutrients tend to remain in the soil longer than nitrogen. Nitrogen can be swept through the grass root zone by rain or watering, and will be depleted quicker in sandy soils than in clay soils. By far the best way to determine if and how much nutrients your turfgrass needs is to have a soil sample analyzed by the OSU Extension Office. Instructions on how to take the sample can be found here.

Blossom End Rot in Tomatoes and
Other Vegetable Crops   
One of the more common questions received by the Master Gardeners regard problems that arise with tomato plants. One common problem is a condition called "blossom end rot". It is not a disease or insect problem and needs no treatment other than perhaps altering your management of the plants. This problem may occur not only in tomatoes but in several other vegetable fruits such as peppers, eggplant, squash, cucumber, zucchini and watermelons.

Blossom end rot is caused by calcium deficiency in the tomato. Calcium is absorbed by the roots and delivered in the plant by the circulation or flow of sap. If there is not enough calcium delivered to the developing fruit, the part furthest from the stem, the blossom end, can develop a localized calcium deficiency. This will begin to deteriorate and develop a leather-like brown discoloration called necrosis which may rot.

The calcium deficiency is usually not due to a lack of calcium in the soil--our soils have plenty--but is a problem with supply to the fruit. When the circulation is reduced, either due to dry soil or hot and windy weather, the plant tends to send most of the calcium containing sap to leaves and not fruit. Leaves are more important for survival.

Other factors contributing to blossom end rot are roots too small for the plant, overly wet soils and too much nitrogen fertilizer.

Excessive soil moisture smothers roots, preventing calcium absorption. Too much fertilizer causes tomato plants to grow more leaves than tomatoes, directing calcium flow into leaves. The type of fertilizer may also be important-ammonium types of nitrogen fertilizer can interfere with calcium absorption, while the nitrate forms do not.

To prevent the problem, water regularly, but don't overdo it. Most tomato plants need about 2 inches of water per week in 2-3 applications The goal is to moisten the soil down to 12 inches or so. One should avoid daily shallow watering. Also, a 2-3 inch layer of organic mulch will help reduce water loss and moderate temperatures.  

There are some varieties of tomatoes that are less susceptible to blossom end rot than others; this includes Celebrity, Jet Star, Mountain Pride, Pik Red and Sunny. Consider this group for your next tomato garden.

Will the Weather Keep This Up?    
How was THAT for July in Tulsa, Oklahoma? It was indeed one of the coolest on record...the 5th coldest since records began in 1905! True, there were a few triple-digit afternoons...there usually are. But there was also a string a four straight days with highs below 80 degrees (ended by an afternoon which topped out at exactly 80 degrees), a couple of record lows, and enough rainfall to satisfy most. Thus, we end July every bit as green as we started it...and probably greener than at any time during the spring.

The weather definitely helped our pocketbooks, at least in terms of utility bills, but a more relevant question would be...did this impact the drought? In the short term, yes it did. Rainfall since June 1 has been very close to, or slightly above normal...Tulsa International Airport saw close to 9 inches during the two-month period. Longer-term drought conditions are still very much alive however, with a year-to-date deficit of over 7 inches. As dry as the year started out, normal early summer rainfall probably seemed like a torrent by comparison.

Now, on to the question that I am sure is on all our minds at this point...will this keep up through August? Early indications are that the overall pattern will favor below normal temperatures and perhaps above normal rainfall (the two often go hand-in-hand in an Oklahoma summer) through August 17 (per the 8-14 day outlook issued on August 3). That doesn't necessarily mean more rainy, 75 degree afternoons or record lows are on our way, or that we are done with triple-digit heat. It does suggest that any dangerously hot weather would be short-lived. And whatever happens, we are on the downhill side of summer.

Question: How can I get rid of nutgrass in my lawn?

Answer: Weed scientists voted on the 10 worst weeds in the world and, No. 5 was yellow nutsedge, also called nutgrass. This weed is a sedge, unrelated to most lawn weeds, and is not sensitive to standard weed killers.

Nutsedge has long slender v-shaped, yellow-green leaves. It loves the sun and wet areas. It is the weed that grows faster than the lawn, which may be seen to pop up two days after mowing. Nutsedge multiplies from seeds and underground "nutlets." A single plant may produce hundreds of nutlets which remain viable for years, even after removal of the parent.

Although difficult, prevention is the ultimate strategy. In general, a healthy, dense and properly watered lawn is less likely to have any weeds, including nutgrass. Also be aware that many infestations start from imported soil and related materials which contain the nutlets.

Once it is established, control is best done by herbicides labeled for yellow nutsedge. Common weed killers are not effective. The chemical names of the three most useful herbicides for homeowners are bentazon, imazaquin and halosulfuron. All have different instructions for usage; the labels must be read and followed. Most will need to be used twice per summer:

Bentazon is marketed as Nutgrass 'Nihilator, Basagran and others. It may be used on all turfgrasses.

Imazaquin is sold under the name, Image. It can be used on Bermuda and zoysia, but not fescue lawns.

Halosulfuron has a catchy brand name of Sedgehammer. It is both expensive and difficult to find. Small packets are available for home- owners, to be used in a hand sprayer. It is more effective if a soap-like material, called a surfactant or "spreader sticker," is added, according to the label. Halosulfuron is safe for all Oklahoma lawns.

Glyphosate, the herbicide found in Roundup and others, will kill nutsedge. It also will kill anything else green in the area. It would be a good choice for nutsedge growing in uncultivated weedy areas, but not lawns.

Click here to send your question to the Tulsa Master Gardeners or see Answers to other Questions on the Web site.