May 2015 / Volume 98       

In This Issue

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

69 degrees 


Rainfall total last 30 days:  

4.15 inches


Donations Keep The Tulsa Master Gardener Program Going Strong
Recognition of this month's donations:


Ann McKellar (in memory of John Smith)


Carroll Hunt (in memory of Warren Wirth)


Almeda Crook (in memory of Warren Wirth)


Katherine Coburn (in honor of Jim Thayer)

The Tulsa Master Gardener Foundation receives no city, state or federal funding for its programs. In fact, the majority of Tulsa's Master Gardener programs are self-funded. While we have many dues-paying members, income received from dues pays for less than 5% of total annual expenses. 

Tulsa Master Gardener's own fundraisers make up most of the income to cover expenses. A significant portion comes from the Tulsa Master Gardener annual plant sale that is held each April. Other fundraisers include the Garden Tour (June) and "garage sales" that occur from time to time. However, one other income source that sometimes gets overlooked is  personal and corporate donations.

To find out how you can help support all that the Tulsa Master Gardeners do for their community, contact the Tulsa Master Gardener office directly. 

4 Ways to Contact Us
Email us at:

See our website at: 

Call: 918-746-3701 from 9-4, Monday - Friday 
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.

May Lawn & Garden Tips
  • Wait a little longer for it to warm up before planting cucurbit crops and okra.
  • Plant vegetable crops in successive plantings to ensure a steady supply of produce rather than harvesting all at once.
  • Cover cucurbit crops with a floating row cover to keep out insect pests. Remove during bloom time.
  • Watch for cutworm damage and add flea beetle scouting to your list of activities in the vegetable garden.
  • Warm-season grass lawns can be established beginning late April from sprigs, plugs or sod. (HLA-6419)
  • Fertilizer programs can begin for warm-season grasses in April. The following recommendations are to achieve optimum performance and appearance of commonly grown species in Oklahoma:

Zoysiagrass: 3 lbs N/1,000 sq. ft.     

Bahiagrass: 3 lbs N/1,000 sq. ft.

Buffalograss: 2 - 3 lbs N/1,000 sq. ft.

Buffalograss/grama mixes: 3 lbs N/1,000 sq. ft.

Bermudagrass: 4-6 lbs N/1,000 sq. ft.

Centipedegrass: 2 lbs N/1,000 sq. ft.

St. Augustinegrass: 3-6 lbs N/1,000 sq. ft. 

  • When using quick release forms of fertilizer, use 1 pound of actual nitrogen per 1,000 sq. ft. per application; water in nitrate fertilizers. (HLA-6420)
  • Mowing of warm-season lawns can begin now (HLA-6420). Cutting height for bermudagrass and zoysiagrass should be 1 to 1� inches high, and buffalograss 1� to 3 inches high.
  • Damage from Spring Dead Spot Disease (SDS) becomes visible in bermudagrass (EPP-7665). Perform practices that promote grass recovery. Do not spray fungicides at this time for SDS control.
  • Grub damage can be visible in lawns at this time. Check for the presence of grubs before ever applying any insecticide treatments. Apply appropriate soil insecticide if white grubs are a problem (EPP-7306). Water product into soil.
  • Proper watering of newly planted trees and shrubs often means the difference between success and replacement.

  • Remove any winter-damaged branches or plants that have not begun to grow. Prune spring flowering plants as soon as they are finished blooming. (HLA-6404, HLA-6409)

  • Control of powdery mildew disease can be done with early detection and regular treatment. Many new plant cultivars are resistant. (EPP-7617)

  • Leaf spot diseases can cause premature death of foliage and reduce plant vigor.

  • Most bedding plants, summer flowering bulbs, and annual flower seeds can be planted after danger of frost. This happens around mid-April in most of Oklahoma. Hold off mulching these crops until spring rains subside and soil temperatures warm up. Warm-season annuals should not be planted until soil temperatures are in the low 60s.

  • Harden off transplants outside in partial protection from sun and wind prior to planting.

  • Let spring flowering bulb foliage remain as long as possible before removing it.

  • Hummingbirds arrive in Oklahoma in early April.  Get your bird feeders ready using 1 part sugar to 4 parts water.  Do not use red food coloring.

  • Keep the bird feeder filled during the summer to entice bird varieties which, in turn, help control insects at the same time.

  • Lace bugs, aphids, spider mites, bagworms, etc. can start popping up in the landscape and garden later this month.  Keep a close eye on all plants and use mechanical, cultural, and biological control options first.

  • Be alert for both insect pests and predators. Some pests can be hand picked without using a pesticide. Do not spray if predators such as lady beetles are present. Spray only when there are too few predators to be effective.

  • Schedule a group tour of The Botanic Garden at OSU between the first of May and late October!

Spring Lawn Care    
Having Bermuda grass in one part of the yard and fescue in another part of the yard presents an issue on when to fertilize.


This is a common dilemma in our area.  We live in a transition zone between where warm season and cool season turf grasses perform best and often our lawns have both types.  The recommendations for each type are quite different, so a plan is important.


The best way to remember when to do what with each type of grass is to focus on the time of active growth.  It is during growth periods that turfgrass needs nitrogen fertilizer and to fertilize at other times may be both harmful and wasteful.


Warm-season grasses - Bermuda, Zoysia and Buffalograss - prefer hot weather and actively grow in the summer.  They become dormant (turn brown) in winter to tolerate the cold.  Any Tulsa area grass which is green in summer and brown in winter is one of these two types.


Fertilize warm-season lawns from April (after green-up) to late August.  Bermuda grasses should get 3 to 5 pounds of actual nitrogen fertilizer per 1,000 sq. ft. in divided doses during this time.  Zoysia and Buffalograss need about half as much nitrogen per season as does Bermuda.  If they are fertilized later, dormancy may be delayed, making them susceptible to winter kill and diseases.


The best time to dethatch or aerate warm season grasses is at the start of their growing season in March and April.  Seeding or sodding of these grasses is best done in late spring - May and early June - after the soil is warm.  This allows time to establish roots before going dormant in winter.

Tall fescue and Kentucky bluegrass are often found growing together.  They stay green all year but go into partial dormancy in the heat of summer and during the colder parts of winter. They grow best in spring and fall before temperature extremes develop.

Fescue should receive fertilizer during its active growth periods as well.  One pound of nitrogen fertilizer per 1,000 sq. ft. three to four times per year is recommended.  Fertilize once or twice from late February through April.  Then, apply another dose in September and again in November.  Never fertilize fescue in summer as it will make the grass susceptible to heat damage and disease.

Cool season grasses often need reseeding due to summer heat and stress loss.  Although reseeding may be done in the spring, fall is far and away the best time to reseed tall fescue and Kentucky bluegrass.


Tulsa Master Gardeners have some helpful guidelines to help you plan lawn care either in their office or on the website.

The Art of Mulching: Do's and Don'ts  


Okay, this is corny but cute, from the King himself, Elvis:  "Thank you, thank you very mulch!

While this article is about suggested do's and don'ts, it is mostly about do's when it comes to the mulching process.  Mulching is one of the gardener's best friends:  it keeps the soil moist, reduces erosion, slows weed propagration, protects against extreme heat and cold, wards off harmful insects, and gives the finishing touches to make your garden look stunning.


Do Consider Mulch Choices:  The good news is that there are lots to choose from that will complement your home, whether it be brick, stone, stucco or siding.  Brownish/red pine mulch goes well with brick houses.  Using a dark mulch can contrast with flowers, improving your landscape design and does not compete with the plants that you are highlighting.  Mulch should be functional without being seen, is the mantra of many gardening schools of thought.  Along with the more popular mulch choices such as shredded hardwood bark, there are also rocks, straw, pine needles, leaves, pecan shells, corn cobs, cocoa bean shells, and seaweed for you to choose from.  Man-made mulches have their place in certain high-traffic areas. but generally not your garden areas where you want to take advantage of the nutrients you can get from the natural mulch materials.


Do Freshen Up the Look and Add Nutrients at the Same Time:  If re-mulching a bed, remove some of the old mulch or, better yet, work it into your soil and then add a fresh batch of mulch. By doing this, you get the best of two worlds, nourishing the soil and giving your garden a fresh, unified look.


Do Mulch to Slow Down Soil Erosion and Run-off:  Having bare soil on your property encourages erosion and sediment runoff, as well as weed germination.  Mulching can significantly help control erosion and weed control.


Don't Skimp on Application:  About 2" - 4" of mulch is recommended for flower and vegetable beds.  Be on the lookout for areas that may need re-mulching as the season progresses where you will want to do "touch-up mulching" to keep the mulch depth adequate and coverage complete.  Please note that if you use pea gravel mulch or inorganic mulch, you will need no more than 2".


Don't Make Volcanoes of Mulch Around Your Trees:    Please do not mound up the mulch up to the base of the tree trunk (same applies to bushes).  This spells sudden death to the tree or bush, causing too much moisture and invites harmful insects to attach to the tree.  Instead.  please consider using the "doughnut" method of application:  none around the base of the tree, leaving a space of 12-18", and then start the mulch application, going out to the tree drip line if possible. Prolonged exposure of the tree trunk to the moist mulch can result in decay of the bark layer of the tree, resulting in poor growth.  Properly applied mulch around a tree should start out a few inches from the trunk and extend at least 3' out from the base of the tree.


Your garden will say, "Thank you very mulch!:"   Happy Gardening.


For additional information, please check these web sites out:,  Fact Sheet HLA-6005 Mulching Garden Soils


Milkweed for Monarch Butterflies (a sequel to last month's article on Milkweed)  
More and more people are becoming aware of the decline of the monarch (and other) butterflies and how the planting of milkweed can help to stem off some of that decline.  However, many folks are uncertain as to the type of milkweed to plant. Don't feel ahead.

There are said to be 73 species of milkweed in the U.S., and monarchs make use of about 30 of them.  The plants serve as a host for eggs, caterpillars and some supply nectar for adult butterflies.  Oklahoma has about 20 milkweed species listed as native across the varied ecoregions of the state and about 10 of them are native to our specific area of the state.  Due to human activities, monarch butterfly populations are in decline related to the loss of native milkweeds which they are totally dependent upon.  We can all help the monarchs by planting milkweeds in our gardens and other butterfly friendly areas.  When planting milkweed, it is suggested you plant one type that is native to your area.   A good place to help what to plant is the Kerr Center for Sustainable Agriculture website which has information about all the native milkweeds in Oklahoma and where in the state they grow best.  


One thing to keep in mind is that monarch caterpillars have huge appetites and can strip a single plant in a very short time. That is why it is recommended several plants be planted.  There are some interesting facts about milkweed which are not widely known.  For instance, worldwide, there are over 2,000 species of milkweed.  The plants are perennial; once established, they should return yearly from the roots.  They also produce abundant seeds which, if stratified in the refrigerator for a few weeks, can be planted with success in your garden.  The toxin in milkweed is good news and bad news.  The bad news is that that the milky sap in the plants is toxic-toxic to pets and children.  If eaten. It can make children and animals very sick and some people develop rashes upon contact.  The good news is that the toxin has no adverse effect on the monarch butterfly.  They accumulate the toxin in their bodies and, if they are eaten by birds, the birds become ill and rapidly learn to avoid not only monarchs, but butterflies which look like monarchs.


One of the current problems in the Tulsa area is that there has been a limited number of plants available.  This will rapidly change because the demand for plants from the garden centers is high.  Seeds of various species are widely available on the internet.  Be advised that some species are ok for our area and some are not.  Some of those that are ok for our area are:


Antelope Horn Milkweed

Broad-Leaf Milkweed

Butterfly Milkweed

Clasping Milkweed

Common Milkweed

Engelmann's Milkweed

Four Leaf Milkweed

Green Antelope Horn Milkweed

Narrow-Leaf Milkweed

Prairie Milkweed

Sand Milkweed
Short Green Milkweed
Showy Milkweed
Swamp Milkweed
Tall Green Milkweed
White Milkweed
Whorled Milkweed
Zizotes (Sidecluster) Milkweed

Also, there are a huge number of organizations which are working together and with the USDA to grow more milkweed and educate the public about the issue, thereby helping to increase monarch butterfly numbers.   A couple of those organizations are:

Monarch Joint Venture


Please join the effort!  




Question:  Now that my vegetable garden is growing, what is the best fertilizer and how much should I use? 

Answer:   There is no "best" fertilizer for vegetables during the growing season.  However, additional nutrients in addition to the native soil are usually needed.  They are applied to the root zone of plants, which is called "side dressing."

The times and amounts of fertilizer to apply depends on the vegetable, type of soil and amount of rainfall.  The Kansas State Extension web site has a very helpful 
chart of how much and when to apply different types of fertilizer as side dressing to a wide range of vegetables.

A soil test will tell you which of the three main nutrients - nitrogen, phosphorus and potassium - may be needed. If a test result is not available and the garden plot has received general fertilizer in the past, use a fertilizer containing mostly nitrogen. Rapidly growing vegetables almost always need extra nitrogen, but in sensible amounts.  The other nutrients are needed as well, but previously fertilized gardens usually have ample or excessive amounts of phosphorus and potassium as they do not leach through the soil as quickly as nitrogen does.  Apply the fertilizer to the area of the plant's roots, but keep it away from the stems to prevent burning.  Fertilizer will need to be gently washed into the soil, but do not apply just before a heavy rain.  Nitrogen is mobile in the soil and is easily carried beyond the plant's root zone with excessive rain, especially in porous, sandy soils. Using a fertilizer with some of the nitrogen in a slow-release form will minimize this water related loss.  An example of recommended fertilizer amounts for vegetables from the Kansas State document - in this case tomatoes - is to fertilize one to two weeks before the first tomato ripens, and again two weeks after picking the first ripe tomato, then again one month later.  Each time, use two tablespoons of a 16-0-0 or one tablespoon of a 27-3-3 strength fertilizer per tomato plant.

Lawn fertilizers are a good choice for fertilizing the vegetable garden.  These often are mixes of quick and slow released nitrogen with little or no phosphorus.  Never use a lawn fertilizer containing an herbicide such as found in "weed-and-feed" preparations.


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