April 2016 / Volume 109   

In This Issue

Weather Stats for Gardeners

Soil Temperature 2" below sod:   

56-59 degrees 


Rainfall total last 30 days:  

2.12 inches

(March normal: 3.31)



2016 Rainfall total: 

3.56 inches

(Normal YTD: 6.81 inches)




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

MG Memorial Donations for Sally Sitler:

Bill Davis
Carroll Hunt
Chester Jacewitz
Lee Kutner
Karen Manera
Ann McKeller
Fran Palmer
Allen Robinson
Carolyn Rogers
Carol Sartin
Jean Seeger
Bill & Vija Sevier
Diane Tracas
Claudia Vandiver
Jo-Ann Wensell
Doug Youngdahl

Other Memorial Donations for Sally Sitler:

Al & Brenda Schiltz - Broken Arrow
Belinda Mantle - Alexandria, VA
William Rodgers - Jenks
Tom & Patsy Patterson - Houston, TX
Diane Knights - Broken Arrow
David & Nancy Crandall - Broken Arrow
Jeffrey Campbell/Stephen Elbel - Hackensack, NJ
Kathryn A. Hicks - Sapulpa
Docia Hendrickson - Tulsa
Coleen Mauk - Tulsa
Nancy & Lee Doss - Doxa, AL
Pam & John Mantle - Tuscaloosa, AL
Jean Jolly - Tulsa
Ron & Leslie Wood - Tulsa
Tim & Glenda Womack - Tulsa
Don & Helen Crawford - Greer, SC
Ronald & Cathy Fovargue - Naperville, Il.
S. Moore - Tulsa
Mike & Peggy Wolford - West Des Moines, IA.
Mary Smith - Broken Arrow
Radiology Consultants, PC - Tuscaloosa, AL
Sapulpa Lunch Ladies c/o Jack & Carol Vermillion
Sapulpa Public Schools - Board of Education


Jean Seeger
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.

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. Finally, one other income source that sometimes gets overlooked are personal and corporate donations.  These are so important in helping to meet our financial obligations and are very much appreciated. 

You can make an online contribution by going to the Tulsa Master Gardeners website and donate directly through PayPal. For other information on how you can help support all that the Tulsa Master Gardeners do for their community, contact the Tulsa Master Gardeners Office by calling 918-746-3701.  Thank you! 

4 Ways to Contact Us
Email us at:

See our website at: www.tulsamastergardeners.org 

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.
April Garden, Lawn, & Landscape 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.
Garden Planting Guide for Warm-Season Vegetables:
Time to Plant*
Days to Harvest
Method of Planting
Bean, Lima
April 15-30
Beans, Green or Wax
April 10-30
Beans, Pole
April 10-30
May 1-20
Seed or Plants
April 10-30 or later
Seed or Plants
April 10-30
April 10-30 or later
April 10-30 or later
April 10-30
Southern Pea
May 1-June 10
Squash, Summer
April 10-30 or later
Seed or Plants
Squash, Winter
May 15-June 15
Seed or Plants
Sweet Corn
Mar. 25-April 30
Sweet Potato
May 1-June 10
April 10-30
May 1-20

  • Don't spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions. (EPP-7319)
  • Continue spray schedules for disease prone fruit and pine trees.
  • Fire blight bacterial disease can be controlled at this time. Plant disease-resistant varieties to avoid diseases.
  • Control cedar-apple rust. When the orange jelly galls are visible on juniper (cedar), following a rain, begin treating apple and crabapple trees with a fungicide. (EPP-7319 , EPP-7611)
  • 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.
    When using quick release forms of fertilizer, use one 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 feeders ready using 1 part sugar to 4 parts water. Do not use red food coloring.
  • Keep the bird feeder filled during the summer and 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 Oklahoma State University in Stillwater between the first of May and late October.

Master Gardeners Spring Plant Sale
Wednesday, April 13th from 4 - 7 p.m.
Thursday, April 14th, from 9 am to 7 pm
Tulsa County Fairgrounds, Central Park Hall, Gate 12
Just another reminder about our spring plant sale.  While it is now too late to pre-order, we will have a wide selection of native plants, proven winners, herbs, veggies, annuals and hard to find plants to add variety to your garden on sale on the 13th and 14th. This year's Herb of the Year, the Chili Pepper, will be featured with recipe suggestions.  Master Gardeners will be available to answer questions and help you choose plants that will work in your garden.  Proceeds from the Spring Plant Sale support the many Tulsa County Master Gardener programs that are provided free in our community.

These plants are sold on a first-come, first-served basis. The sale is open to everyone on April 13th from 4:00 to 7:00 pm and April 14th from 9:00 am to 7:00 pm. SHOP EARLY, DON'T MISS THIS! 

MG Program: Tuesday Evening Classes

Each year in the Spring, the Tulsa Master Gardeners conduct informal classes every Tuesday evening during April and May to help educate the public on research-based horticultural information.  This year is proving to be every bit as good as in the past, with an impressive list of popular subjects, as follows:

April 5th      Butterfly Gardening
April 12th    Sun Loving Annuals and Perennials
April 19th    Herb Gardening for Dummies
April 26th    Shade Gardening with Annuals and Perennials
May 3rd       Planting for Pollinators: Bees, Butterflies, etc.
May 10th     Keeping Critters under Control - IPM in the Garden
May 17th     Straw Bale Gardening - Grow Anywhere
May 24th     What's the Deal with Native Plants?
May 31st      Made in Oklahoma - Native Trees & Shrubs

The classes are open to the public, they are free, and you can come as you are.  They begin at 5:30 p.m. and generally last 30 minutes, until 6:00 p.m.  However, the speakers hang around as long as there are questions and there is interest.  The programs are held in the large classroom of the OSU Extension Office located at 4116 East 15th Street in Tulsa (enter at Gate #6 of the Tulsa County Fairgrounds off 15th street).  See you there!


Companion Planting: A Historical Practice
Companion Planting is a gardening term that has gained popularity in recent years but it is actually a historic practice utilized by Native Americans in the "Three Sisters" planting system. Most people have heard of this concept where corn provides the pole for beans, beans fix nitrogen, and squash provides a living mulch for the other two.

In more modern gardening, companion planting can be any planting of "two or more plant species in close proximity so that some cultural benefit is derived." It is based primarily on historical observation and practice. However, with science taking a greater interest, the term companion planting has become more definitively named "intercropping."
The practice of companion planting can be beneficial in several ways. Trap cropping a "sacrifice" plant can divert pests away from the desired plants. Nitrogen fixation-plants, specifically legumes, fix atmospheric nitrogen in the soil where they and other plants are being grown. Still other plants can exude chemicals from roots or aerial parts that suppress or repel pests. Nurse cropping with tall, sun-loving plants can provide a canopy for low, shade-tolerant plants. Finally, a number of plants attract beneficial insects that prey on pests and/or attract pollinators.
So, is companion planting/intercropping a sound gardening practice? The "Three Sisters" technique has historical evidence to support the positive benefits of the practice. You should always bear in mind, if attempting any gardening technique, when environmental requirements (i.e. sun, soil, and water) of our plants are met they will grow strong and healthy. If utilizing the companion planting/intercropping technique, as with anything in your garden, first identify the problem and explore all possible solutions before taking any action.
Since tomatoes are the ever popular warm season vegetable of choice here in Oklahoma, here are some companions that may prove beneficial: asparagus, basil, beans, borage, carrots, celery, chives, collards, cucumber, garlic, lettuce, mint, nasturtium, onion, parsley, and peppers. On the flip-side, there are "antagonists" that are not suited to be in proximity to tomatoes, such as corn and potatoes.  

For more information on companion planting, refer to OSU's fact sheet HLA-6431.  There are many other companion plantings that may be beneficial...however, bear in mind, no scientific evidence could be found to support the benefits of the listed companions. 


Spring Lawn Care
      law n fertilizer bermuda lawn  
As we approach spring and summer and the fast growing season, there are several things that an help improve our lawns.  Some of the most important things are:  Dethatching, Aeration, Fertilization and Proper Watering. 

Dethatching: Thatch is made up of leaves and roots that haven't fully composted and are found along the soil line.  When it becomes more than � inch thick, it should be removed.  If the thatch is less than one inch thick, small yards can usually be dethatched by the land owner, just by raking.  However, if the thatch is over one inch thick, you might need to rent equipment or hire a yard professional.  Dethatching should be done before the grass begins to green-up.
Aeration: Aerification is a process used to reduce the compaction of soil.  Over the years of having a lawn in the same place, soil becomes compacted and the aeration process is needed.  The process is the removal of soil in � to 1 inch diameter holes and approximately 2 inches deep.  This is usually done by professionals; however, rental equipment is available.  If the soil is really  compacted, watering should be applied 2-4 days before aerification.  You can use a lawn mower to chop up the cores of dirt and grass caused by aeration.
Fertilization: Lawn fertilization rates and dates will vary,  depending on your type of grass.  Fertilization of Bermuda Grass occurs from April to August for quick release and in April, June, and August for slow release.  For fescues and ryes, fertilizer should be applied in March, possibly April, then in September and November.  The fall fertilizations are the most important.  Fescues should never be fertilized in the summer.  Unless a soil sample shows that you need Phosphorus (P) or Potassium(K), all you generally need  is Nitrogen (N).  Buy a bag of fertilizer with zeroes on the end numbers, such as  22-0-0 or 33-0-0 and carefully follow the instructions on the bag.
Watering: Proper watering is an important part of lawn care.  The irrigation of the grass should NOT be on a frequent, short-term schedule because frequent, shallow watering will not coax roots to grow deep, which helps them withstand hot, dry periods later.  It is better to water more infrequently and for longer times, allowing the water to penetrate deeper into the soil, thus coaxing the roots to grow deeper.  You can determine your watering needs by probing the soil and determining the wetness of the soil approximately 6" deep.
Establishing A Lawn In Oklahoma   HLA-6419
Lawn Management in Oklahoma   HLA-6420
Thatch Management in Lawns   HLA-6604
Bermuda Lawn Management Calendar   L-441
Fescue Lawn Management Calendar  L-442

These can be found on our website or at the Master Gardener  Office located at 4116 East 15th Street Tulsa, Ok. or call 918-746-3701.

Planting an Herb Garden

Planting an herb garden is a no-brainer and will heighten your gardening enthusiasm!  Herbs usually have fewer pest or fungal problems and require only minimal watering when established. Fertilizer is also unnecessary for most herbs unless frequent, heavy harvests are desired.  Herbs can be grown in a designated bed, as part of a vegetable plot, in a perennial flower border or in just about any container you have around the house.

Type of Herbs

Many culinary herbs are members of two plant families.  The mint family (Lamiaceae) includes basil, oregano, marjoram, catnip, all of the mints, as well as rosemary, thyme, lavender, summer savory, and sage, and are all grown for their aromatic leaves.  Over time, mints become invasive, so plant them in a container!

The carrot family (Apiaceae) includes dill, parsley, chervil, cilantro, fennel, and lovage.  They are all grown for foliage and some for seeds as well.  These plants have a more upright, leggy habit and require somewhat moister conditions along with deeper, looser soil.  Common culinary herbs from other plant families include chives (Alliaceae), borage (Boraginaceae), tarragon (Asteraceae), and sorrel (Polygonaceae).
Acquiring Herbs
Seed packages for herbs are at most garden supply stores or you can purchase a variety of young herb plants at the many spring garden markets that are going on right now.  Space young plants with the mature plant size in mind.  Crowded conditions will result in tall, weak plants and poor air circulation will encourage disease.
Perhaps a friend has a successful herb planting and, as such, many perennial herbs may be propagated by division.  For example, a clump of chives or a mound of creeping thyme can be divided with a shovel in spring and transplanted.

Soil properties

The majority of herbs demand a well drained soil.  Avoid heavy clay soils.


Most herbs require at least 6 hours of direct sunlight in order to grow well and all-day sun is even better.  The more intense the light, the more oils that will develop within the glands of the foliage and stems, creating stronger fragrances and seasonings.


Water thoroughly once a week by soaking the soil to a depth of 8 inches to ensure that the root zone is receiving adequate moisture.  Container-grown herbs must be watered more frequently, even daily, if days are hot and sunny.


Culinary herbs may be harvested throughout the growing season by snipping sprigs and leaves as they are needed.  Many will contain the best flavor if harvested mid-morning and just before flowering.
For mint-family herbs, make the cut a few inches down the stem and just above a set of leaves.  New growth will arise from buds at this point and a bushier plant will result.  For carrot-family herbs, cut each leaf stalk at the base of the plant; for parsley or cilantro, trim the tender leaf blades; for dill, trim the ferny growth.

Click the link below for a list of common herbs, details on preserving and related recipes: 

Happy herbing!



 When should I plant my tomato plants in the garden?  

Answer: Plant tomatoes after the average last frost date, which for us is mid-April. Cover them for any late cold spells. Mulching is beneficial, but don't add it until the soil warms. 

Other vegetables best planted in the last half of April are three types of beans - Lima, green and pole beans - along with cucumbers, eggplant, okra, peppers, pumpkins and summer squash. Wait until May to plant cantaloupe, southern peas, winter squash, sweet corn, sweet potatoes and watermelon.

When selecting varieties to plant, always consider ones resistant to common insects and disease. For more information, get a copy of Oklahoma State University's Oklahoma Garden Planning Guide and Vegetable Varieties for Oklahoma at the Master Gardener's web site, tulsamastergardeners.org.

These vegetables need full sun and perform best in a garden bed that has been prepared by tilling in large amounts of well-rotted compost.

Be sure to remove all trash from last year's crop, which may contain insects and disease. Vegetables should be planted in an area convenient for watering and daily inspections. Consider staggering plantings to lengthen the production time of crops. 



My soil is almost pure clay. I am thinking of making a raised bed for my vegetables. How do I create one? Would gypsum help the clay soil to drain better?  

Answer: Gypsum was once thought to chemically change clay soils to improve drainage. But, studies have shown it to be ineffective for this purpose. 

Raised-bed gardening is an excellent solution for poorly draining clay soils. The beds can be anything from a flat, stand-alone mound of good loamy gardening soil to a more complex one framed and held together by wood or stone. The imported soil depth can be anywhere from 6 to 24 inches above the underlying clay soil.

Overall size depends on the available space and your ambition and imagination. A vegetable garden might be 3 to 4 feet wide and 25 feet long. This size would allow comfortable access and would produce a lot of veggies, because plantings may be placed closer together.

The bed needs full sun, and the best light exposure occurs if planted in a north-south direction. All raised beds will need water, so they should be constructed with water access in mind. A drip irrigation system is a perfect solution.

There are several benefits to raised beds. Because there is no foot traffic, more space is available for planting, and soil has less compaction and drains better. This makes for healthier roots. Also, amendments to the soil - such as compost and fertilizer - are applied only to growing areas, which is more efficient.

Raised beds also may have a longer growing season. They warm up earlier in the spring than do traditional gardens. Rainy weather is less of an obstacle to working in the garden, because there is no foot traffic, and the soil drains rapidly.

Dense planting shades the bed soil, keeping roots cooler and reducing water evaporation in summer. The shading effect also keeps weeds crowded out, especially if mulch is used.

Some people have logically questioned the use of pressure treated lumber in constructing these beds. Pressure treatment uses some chemicals to prevent wood decay. University-based studies have shown no adverse effect on plant growth or food safety in using these materials.

Obtain OSU's free document "Raised Bed Gardening" from the Master Gardener web site.  See Fact Sheet HLA-6033.



When should I think about aerating my Bermuda lawn? 

What is the difference between aerification and dethatching? 

Answer: Spring is a good time to either aerate or dethatch your Bermuda. The processes are different, but related. Both may be used to reduce thatch in lawn grass. 

Thatch is mainly a problem in Bermuda grass and zoysia lawns. It is due to heavy production of stems above and below the ground faster than they can be decomposed. Excess thatch accumulation impairs the movement of water, nutrients and air into the root zone. This promotes shallow root development and turfgrass diseases. Improper mowing, over-fertilization and over-watering are contributors to thatch.

To determine how much thatch is present, remove a 3- to 4-inch deep plug of grass. The brown layer of dead material between the top of the soil and the bottom of the green grass is thatch. A thatch layer under a half inch thick is acceptable; anything more is an indication for dethatching. You may hire someone to do the job, or rent a dethatching machine. This machine's multiple vertical blades slice down to the top of the soil, pulling up the dead thatch - which must then be removed. Dethatching may be done now, but the ideal time is before spring green-up.

Aerification is done mainly for soils that are compacted due to heavy traffic or simply have too much heavy clay. The process, like dethatching, is done with a special machine that is either hired or rented. The best machine has a large number of finger-sized hollow tubes on a roller that plunge into the ground and remove plugs of soil up to 2 inches long. The holes produced allow better flow of water, nutrients and air into the soil.

The process of aerification is not as destructive to the turfgrass and can be done later in the season than dethatching. As plugs are removed, a lot of thatch is also removed and it can be used as a dethatching tool for smaller amounts of thatch. When the thatch is up to an inch thick, a dethatching machine would be the best choice.

For more information, obtain OSU's free fact sheets:
HLA-6420        "Lawn Management in Oklahoma," 
HLA-6604        "Thatch Management in Lawns"
L-441              "Bermuda Grass Maintenance Calendar" 

All are available on the Master Gardener website or at the OSU Extension office located at 4116 E. 15th Street in Tulsa.