July 2011 / Volume 51 

In This Issue
July Gardening Tips
Time to Plan Your Fall Garden
A Word About Frost Dates
Ask A Master Gardener

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

80 degrees 


Rainfall total last 30 days:  

2.59 inches

4 Ways to Contact Us
Email us at:

See our website at: www.tulsamastergardeners.org 

Call: 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 Information?

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.
How to Plant a Tree in Oklahoma Soil
Show and tell.
Fescue Lawn Care
12-month maintenance calendar.
Bermuda Lawn Care
Ditto above.
Trees for Tulsa
A list of 50 recommended trees with descriptions.
Crape Myrtles
A list of over 100, by size and color.
Oklahoma Proven Plants
The new list for 2011. State horticulturists, nurseries and growers pick their favorite plants, shrubs and trees.
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. Register 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.
July Lawn and Garden Tips
  • Make fall vegetable garden plantings in July. See HLA-6009 for recommendations.
  • Spider mites love hot dry weather. These tiny pests attack many plants, especially tomatoes. Wash them off with jets of water and use organic pesticide such as soaps or horticultural oil. Neem oil is a good choice.To check for spider mites, shake leaves over white paper. If tiny spots that fall on the paper start moving, chances are they are spider mites. 
  • Continue insect combat and control in the landscape, garden and orchard. (Lawn & Ornamental: EPP-7306, Garden: EPP-7313, Fruit trees: EPP-7319). Check pesticide labels for "stop" spraying recommendations prior to harvest.
  • Insect identification is important so you don't get rid of the "Good Guys." (EPP-7307) When using any insecticide spray early in the morning or late in the day when bees are not present.
  • Expect some leaf fall, a normal reaction to drought. Water young plantings well. Mulching around your trees is the best protection against lawn equipment. Mulching also speeds the growth of younger trees as well as preventing weeds and conserving water.
  • Water plants deeply and early in the morning. Most plants need approximately 1 to 2� inches of water per week. Use  liquid fertilizer for annual flowers every 3-4 weeks. Follow directions, too much fertilizer is worse than not enough.
  • Divide and replant crowded hybrid iris (bearded iris) after flowering until August.
  • Lawns mowed high are better able to tolerate summer heat. Mowing heights for cool-season turf grasses should be 3" during hot, dry summer months. Gradually raise mowing height of bermudagrass lawns from 1� to 2 inches.
  • Sharpen or replace mower blades as needed. Unsharpened blades are an invitation to disease and allow more stress on the grass.
  • Vegetative establishment of warm-season grasses should be completed by the end of July to ensure the least risk of winter kill. (HLA-6419)
  • Brown patch disease of cool-season grasses can be a problem. (HLA-6420)
  • Meet water requirements of turf during July and August heat. Bermuda lawns need one inch and fescue 2 inches of water per week. Water lawns 2-3 times weekly trying to wet the ground 6 inches. Water lawns and flowers in the mornings so they will be dry by night. (HLA-6420)
  • Fertilization of bermuda and zoysia grasses can continue if irrigated. (HLA-6420) (Do not fertilize fescue lawns until September.)
  • Soil tests are recommended every three years.Don't apply phosphorus (that's the middle number of the three numbers on the bag label) to lawns that already test adequate for this nutrient.
  • Watch for bagworms on your arborvitae and junipers. An insecticide such as B.t. (bacterial insecticide) is effective while the worms are still small. B.t. is safe for people and pets. 

Time to Plan Your Fall Vegetable Garden  

Generally, when we think of plating a garden, we think of spring planting and a summer harvest. Unfortunately, many vegetable gardeners settle for the spring planted crop and do not take advantage of the fall garden. Some would argue that vegetables that ripen and mature in the cool of the fall have better flavor than spring crops which mature in the heat.

In any case, the fall garden offers a second opportunity for vegetables that should not be overlooked. The planting, however, has some different challenges than the garden in springtime.

These challenges, along with information about when to plant specific vegetables are addressed in OSU fact sheet HLA-6009.

Fall vegetables fall into two categories: those sensitive to frost and those resistant to it. Success depends on learning the usual number of days from planting to harvest of each vegetable and learning its cold sensitivity. Our area's average first frost date is Nov. 3 and the first hard freeze is 2-3 weeks later. Fact sheet  HLA-6009 has this information, along with recommended dates of planting in our area. It also suggests whether planting seeds or transplants (seedlings) is best.

Frost-tender vegetables that should be planted now are: beans, sweet corn, eggplant, peppers, pumpkin, squash, carrots, broccoli and Brussels sprouts. The ever-popular tomato plants may also be planted now for a fall crop, arguably the best tomato crop of the season.

A number of vegetables do well planted later in August, including: green peas, lima beans, beets, cabbage, collards, Irish potatoes, leaf lettuce, radish and turnips. There are other cold-hardy plants that should be planted even later. For example, garlic, leeks, onions and kale should be planted in early September.

The two main concerns with starting the fall vegetable garden are coping with the hot soil and maintaining adequate seedbed moisture. Most vegetable seeds will not germinate when the soil temperature is higher than 85 degrees. Tulsa's current soil temperature is about 85 degrees, so some method of cooling is needed.

One strategy for coping with this is by planting seeds in a furrow deeper than one you used in your spring garden, and covering the seeds with the same amount of soil as recommended in spring. The seedbed in the furrow should then be shaded with mulch, screen wire, shade cloth, or similar materials until the plants emerge from the soil.

Also, you must use some method of maintaining constant moisture, either watering by hand or using drip irrigation. The frequency of your watering will depend on the weather.

Some vegetables will do much better by seeding in a protected seed flat, then being transplanted into the garden. Broccoli, cauliflower, cabbage, leaf lettuce and Brussels sprouts do well germinated in this fashion.

Success of fall vegetables is achievable but requires planning and forethought. If you plan on a fall crop, get the fact sheet mentioned above and also consider fact sheet HLA-6032, "Vegetable Varieties for the Home Garden in Oklahoma" for further suggestions. 

A Word About Frost Dates   

The average date of the first frost referenced in the article above is taken from data at the official reporting station, located at Tulsa International Airport.One should keep in mind that while this will be fairly representative within the City of Tulsa, outlying areas of Tulsa County may have a considerably earlier first frost date, due to the effects of urbanization on temperatures.


If you live in a more rural area, especially in a low lying one such as a river valley, you may want to consider your frost date to be a week or even ten days earlier. 


To view additional information about frost dates in your area click here to visit the frost and freeze page of the National Weather Service site in Tulsa, or click here to visit the climate page of the Oklahoma Mesonet.

Question: When is the best time to divide my peonies?

Answer: Peonies, from the genus Paeonia, became popular in the Midwest when cut flowers were needed for Memorial Day decorations. They have been described as the closest thing to a rose in beauty and fragrance. The peony resents being disturbed and seldom requires division, so only dig when plants are not flowering profusely anymore, or more coverage is desired in the garden by spreading them out. Dig root clumps carefully in September, so as not to bruise them. Each fleshy root division should have 3 to 5 'eyes' or little pink noses. These pink noses will produce shoots for next season. Plant each root division one to two inches deep; if planted too deeply the peony will produce foliage and no bloom. Remove all foliage to the ground after it dies back in the fall to prevent fungal diseases the next spring. Unlike most perennials, peonies actually benefit from planting in fall rather than spring. Also, ants do not help or hurt peonies, as some think. They are naturally attracted to the nectar of the flowers and like to remain close to the plants. Check out the many new varieties of peony, like the "Bric-a- Brac" peony in the photo.

Question:  I have found grayish bags containing an insect when mashed, on my arborvitae, bald cypress and some of my junipers. Will they do much damage and how do I control them?

Answer: Bagworm caterpillars make distinctive 1.5 to 2 inch spindle-shaped bags that may be found hanging from a variety of trees and shrubs in the landscape. They prefer arborvitae, pine, spruce and cedar, but may also be found on deciduous trees. These bags are sometimes mistaken for pine cones or other plant structures. The female moths cannot fly, but tiny caterpillars spin strands of silk that are carried by the wind; this is called 'ballooning'. Larger larvae may crawl to adjacent plants. In early fall, the mature larvae go in search of immobile females in their cocoons or bags. The female lays 300 or more eggs in the bag and then crawls out and dies. The eggs overwinter in the bags to hatch and emerge the following June. The larvae then weave new bags from silk and plant material to conceal themselves as they eat and grow. Bagworms can defoliate a plant and, in the case of heavy infestations in consecutive years coupled with other stresses, may kill the plant. Control of small numbers can be achieved by simply picking off the bagworms and destroying them. If an insecticide, such as B.t. or Bacillus thuringiensis, is required, control is best achieved when bagworms are small and less than � inch in length.

Question: Two of my five tomato plants look like the leaves are turning brownish white and curling, is it a fungus or insect damage? The vigor of the overall plant is not diminished.
Answer: We have seen examples of what you have described on tomato plants brought into the Master Gardener office this month. Upon closer observation under the microscope, the brownish white on tomato leaves was found to be the damage done by thrips. Thrips are tiny insects with narrow, elongated bodies. The "silvering" appearance of thrips damage is caused by the rasping of the leaf tissue with their mouthparts. Small black fecal specks are also usually found. Damage to fruit appears as a cloudy discoloration and results in uneven ripening of the maturing fruit. Generally, thrips damage is considered cosmetic and, therefore, the need for control procedures should be questioned. If cosmetic appearance is important, control should be initiated soon after thrips are detected. Once populations are well established, control is often difficult. Insecticides do not work equally well on all pests; therefore, correct diagnosis is critical to matching the right insecticide to the identified pest. This is a good example of a situation that is best identified by bringing the specimen into our office, located within the County Extension office at Gate 6 of the Fairgrounds. Office hours are Monday through Friday, from 9AM until 4PM.

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