May 2013 / Volume 74                  

In This Issue
May Lawn and Garden Tips
Compost Contest and Bin Sale
Free Gardening Classes in May
Leaflets Three...Let it Be!
Sweet Relief and May Frost
Ask A Master Gardener...Moles

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

55 degrees 


Rainfall total last 30 days:  

5.08 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 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.
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.
Crape Myrtles
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.
May Lawn and Garden Tips 


  • Warm season vegetables like tomatoes, squash, cucumber, pumpkins, eggplant, okra, sweet potatoes and peppers may be planted from mid-April onward once soil temperatures reach 60◦. Click here for the Oklahoma Garden Planting Guide.
  • The first fruit on the strawberry plants may appear by late this month. Newly planted strawberries should have the blossoms picked off until they become well established. Click here for more information on growing strawberries. 


  • Seeding of warm-season grasses such as Bermuda, buffalograss and zoysia is best performed in mid-May through the end of June. Soil temperatures are warm enough for germination and an adequate growing season is present to promote winter hardiness.


  • If azaleas need fertilizing or pruning, do it now after blooming is completed.  
  • Continue to plant summer annuals, summer bulbs such as cannas, dahlias, elephant ear, caladiums and gladiolus.
  • Allow foliage of spring blooming bulbs to die back before removing. These bulbs may be dug and divided after foliage dies. Click here for more bulb information or see the article on bulb care below. 
  • Mophead Hydrangeas may change from blue to pink blossoms depending on the soil pH (acidity). Do a soil test and add either lime or aluminum sulfate to adjust soil acidity to change colors.
  • Pine needle disease treatments may be needed in mid-May. Click here for more information. 
  • Click here for tree pests that will appear in May.
  • Observe roses for development of insects such as aphids and black spot disease. Spray as needed.

  • Early flowering deciduous shrubs such as forsythias, weigela, and azalea may be pruned back after they have finished blooming, but only if pruning is needed.

  • Bagworms may appear on juniper and arborvitae late in May. Pluck them off by hand and spray with an organic herbicide containing Bacillus thuringiensis (Bt). Bt is safe for people and pets. Call Master Gardeners for addition suggestions.

  • Lace bugs may begin to feed on azalea, pryacantha and sycamore trees. Contact the OSU Master Gardeners for additional recommendations.

Compost Contest and Bin Sale 
Saturday, May 4, 2013, 7 am - 11 am
Cherry Street Farmers' Market


Garden Gourmet Compost Bins will be sold for $45. The M.e.t. will sell the bins at the lot next to the Cherry Street Coffee House.


Compost Contest prizes include: 

$50 Membership to the Oklahoma Centennial Botanical Garden
$25 gift card to Sam's Club
$25 gift card to Southwood Landscape & Garden Center

Become the hero of dirt. Win the recognition of every gardener throughout Tulsa. Bring your compost entry to The M.e.t. & Tulsa Master Gardeners Booth between 7 a.m. and 9 a.m. Please submit it in the bottom half of a cut-off milk jug with no identifying marks. Include your compost "recipe" on an index card. Include as many details of your compost as possible. Judging will begin at 9 a.m. Winners will be announced at 10 a.m. Trophies and prizes will be awarded to First Place, Second Place, Third Place and to Best Compost Recipe.

For more information, visit or  

Free Gardening Classes in May    

Tulsa Master Gardeners offer gardening related classes on the dates shown in the table below. Each presentation starts at 5:30 pm and generally last 30 minutes with another half hour for discussion. These classes are free and there is no need to register, just show up. They are held in the auditorium at the OSU Extension Office, which is on 15th street at gate #6 into the Tulsa Fairgrounds.


Proven Perennials


Tough Plants for Tough Summers


Ground Covers, Good Alternative for Shady Areas


Drought Tolerant Plants

For more information on other upcoming classes and dates, visit our website.  

Leaflets Three...Let it Be!   
Poison ivy is a lot like ants at a picnic....a real nuisance. And, if you're one of the majority of people that are highly allergic to it (about 75% of the population is), it can be a real party killer. A common plant in Oklahoma, poison ivy is one of only three plants in the United States that can produce a severe contact rash. Poison oak and poison sumac are the other two, but fortunately both of these are rare in our area.   Luckily, identifying poison ivy is relatively easy. It has three pointed leaflets which may have either smooth or toothed edges. The leaves vary in sizes from one to five inches in length with the middle leaflet having a longer stem than the other two. The plant may show itself as either a low-growing vine, a large tree-climbing vine with thick hair-like tendrils, or a shrub. The leaves are often bright red in the fall and many of the plants produce grayish-white berries. While the berries are also poisonous to humans, interestingly enough, they can be eaten by birds with no harmful effects.

The actual part of the plant that is poisonous is the oil, called urushiol, which is found on all parts of the plant leaves, stems and roots. It is easily absorbed by casual contact. Worse yet, it can also be absorbed into clothing where it may persist for months if not washed, or it can be spread by droplets in smoke if the plant is burned. Urushiol can be washed from the skin with soap and cold water if done very soon after contact (within about 10 minutes). Once absorbed by the skin, it cannot be washed off. A rash then develops hours to days after contact by sensitive people. However, contrary to popular belief, the rash will not spread the toxin to other people.  
Poison ivy should be eliminated by digging and removing all of the plant (including the roots) or by use of herbicides. Do not use a weed-eater for eradication. If the plant is too large to be removed in whole, prune to the ground and apply herbicide to the remaining stump. All removed plant parts should be bagged and discarded. Any planned contact with the plant should include disposable rubber gloves, long sleeves and full eye protection. Immediate washing of clothing with regular laundry detergent will remove any toxin. Just because it may appear to be dormant in the winter, be aware that all parts of the plant contain a toxin at all times of the year (including the berries).

Herbicides are effective but may need more than one application. Both Glyphosate (found in Roundup) and triclopyr (found in Bayer Brush Killer Plus or Ortho Brush-B-Gon Poison Ivy) are quite effective. Triclopyr is more effective, will not kill grass in the area, but persists in the soil for several weeks (replanting cannot be done during this time). Roundup is non-selective and will kill anything green that it comes in contact with but becomes inactive by the soil and has no significant residual activity.

Have fun outside, but be aware of this pretty little plant. It could ruin your day...or week. For more information on poison ivy, feel free to call the OSU Extension Office hotline and speak to a Tulsa Master Gardener.

Spring Bulb Care        

The gorgeous blooms of the tulips, daffodils and crocus are gone. Now what do I do with all this green foliage? The answer:  let it turn yellow. This is the mechanism by which the bulb replenishes it's energy for next year's blooms, so the foliage should not be cut when the bloom fades. The leaves produce food as long as they are green. Food which is stored in the bulb is used the following year for growth and bloom. It takes several weeks for leaves to ripen and often they are not ready for cutting until early summer. Some gardeners like to braid or rubber band the foliage to help hide it, but the leaves need sun exposure to properly store food.


Daffodils and crocus are great easy-care perennials. After flowering, cut only the bloom stalk off.  They need about six hours of direct sun for six weeks after blooming. If the foliage is left until it turns yellow, daffodils will come back year after year. Daffodil bulbs begin summer dormancy after blooming. They are best fertilized while roots are growing, either in the fall or in late winter when the leaves first emerge from the ground.


Tulips are another story in our climate. Are they a perennial or an annual? Most Tulsa gardeners treat them as annuals, replanting them every year. If your current post-bloom tulips look objectionable to you, pull them out and throw them away or put on your compost pile. If you are a gambler, let the tulip foliage whither naturally and perhaps you will get a small amount of repeat bloom next year. If they are in an area that is heavily watered during our sweltering summers, the bulbs may rot in place and Mother Nature will turn them into natural compost.


You can dig them out after the foliage yellows, lay them out to dry on a tarp in the shade for about ten days, then cut the tops off. Discard the tops and store the bulbs in an old onion sack or pantyhose so they have air circulation. Re-plant next fall and see what happens. They will probably bloom, but the flower will be smaller and they will not be as prolific as the first year.     


Camouflaging Foliage

A more creative and satisfying way of dealing with ripening bulb foliage is to hide it with the leaves and flowers of a second plant. Why not plant some of your favorite annual bedding plants in front as well as around your bulbs? Of course, if the annuals are slightly taller than the bulb foliage, it will certainly help the disguise. Dealing with the issue this spring may help you plan out your planting scheme for next fall.

For more information on bulbs, visit the Tulsa Master Gardener website.

Sweet Relief!        

Slowly, but surely this spring, we have put a serious dent in the extreme drought that has gripped our area the past 2-plus years. In general, areas south of I-44 (again, what is it about I-44 and weather?) have seen enough rain in the past 30 days to eliminate drought altogether, while those north have at least seen enough to reduce the severity, and all but rid us of short-term effects at least. Soil moisture indices now show that most of us in northeast Oklahoma have near saturated soil down to 24 inches!

Long term impacts still persist in some areas...meaning more rain will be needed to refill area farm ponds with runoff. Hopefully with the near saturated ground, the typical heavy rains of May and June will help with this...but the weather has been anything but typical of late!

Beware of Frost in Early May!!!!

Speaking of non-typical weather, most of Tulsa county has seen at least a light freeze in late April this year, and current data (as of April 28 suggests another unseasonably cold airmass will descend on us next week around May 3-4. While freezing temperatures are not in the forecast at this time, we recommend you keep a VERY close eye on forecasts the next several days, especially those who live in a "frost pocket" (an area generally more prone to frosts that surrounding locations). Incidentally, the latest a freeze has been observed in Tulsa was May 2nd, way back in 1909. This is a record that needs to stand a while longer!.

Question: Our lawn has been torn up either by moles or gophers, I'm not sure which it is. How do we get rid of them?

Answer: Moles eat only worms and insects. Earthworms make up the bulk of their diet, not white grubs. Moles do not have the teeth to eat plant roots, while gophers eat plant roots with enthusiasm. Moles produce superficial tunnels; gophers have deep hidden tunnels. If you see tunnels, you have moles.

Moles occasionally produce small mounds. Gophers make many mounds, typically over a foot wide and horseshoe shaped. Moles are territorial, with usually only two to three per acre, while there may be 20 or more gophers per acre. Moles are the bigger problem, so we'll deal with them first. Look for gopher answers in another column.

Superficial mole tunnels are of two types. There are feeding tunnels which, although prominent, may be used only once. Other tunnels are for traveling. Tunnels next to hard structures, such as walks, driveways and garden edging are more likely to be frequently used traveling tunnels. The importance of this information is apparent when you attempt to eliminate them.

Numerous products are sold and suggestions made to get rid of moles -- most of these are not science-based and are ineffective. There is one scientific report of a castor oil-based repellent having a temporary benefit, but the mainstay of control should be either traps or one of the poison gel worms.

A common conclusion among many homeowners is that the traps and worms don't work -- but they do. In fact, they work well if used properly. The key step for success is to identify an active tunnel. To do this you should compress a tunnel segment, mark the spot, and inspect regularly. Tunnels will be re-expanded if active, and this is where traps or worms should be placed. Traps come in three varieties -- scissor, harpoon or loop traps. These are listed in order of effectiveness, scissors being most effective. Garden centers usually sell the harpoon traps, the others are available online. When using any trap, instructions must be followed completely.

After setting the trap, all light and air currents must be excluded by either using loose dirt filled around the trap or covering with a bucket. If not successful in two to three days, move it to another site. The scissor and loop traps retrieve the dead moles, while the harpoon trap may not retrieve the mole. The absence of a dead body may lead to a conclusion of failure with this trap. Poison gel worms are a new addition to mole control. Professional turf grass managers report them to be successful, scientific studies are not available. Two of the products available are Talpirid and TomCat. They come with important instructions which must be followed. First, the poison should not be used around pets or children. Like traps, they are not effective unless placed in an active tunnel, excluding all light. Lack of mole activity will indicate success.

Contact the OSU Extension office for additional information on Mole control.

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