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June, 2010                                                                Number 38 
Soil temperature on May 29: 71 degrees                               Rainfall past 14 days: 2.79 inches
Ask a Master Gardener

We have a mystery shrub in a hedge (picture enclosed) that has waxy leaves and is now in full bloom with white blossoms. Can you identify it?
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The "mystery shrub" is the Ligustrum japonicum or Japanese privet. The shrub grows to mature height of six to sometimes twelve feet. It will grow in partial shade and puts on a panicle of white blooms with four white petals and yellow or orange stamens in late spring or early summer, followed by black fruit in fall. It is best pruned after flowering again in late summer.

How can I change the blooms on my hydrangea from pink to blue?
Blooms on the Hydrangea macrophylla can be made to turn from pink to blue by amending the soil with aluminum sulfate to make it more acidic (in other words, lowering the soil pH). Plants should be at least 2-3 years old. Authorities recommend a solution of oz (one tbsp) of aluminum sulfate per gallon of water. Water plants well in advance of application and apply the solution cautiously to the soil, as too much can burn the roots. The blooms can be changed from blue to pink by adding dolomite lime to the soil several times a year to make it more alkaline, or to raise the pH.

Can you give me a list of perennials that do not need a lot of water for the summer garden?
Following is a list of xeric perennials for our zone seven. "Xeric plants" are characterized by relating to, or requiring a small amount of moisture, as a xeric habitat. Remember that all new plantings require more water until the roots can become established. The list includes Blanket flower, Russian sage, Tickseed and other coreopsis, agastache, bellflower, Black-eyed Susan, candytuft, catmint, daylily, Dusty Miller, gazania, Bearded iris, Lamb's ear, lamium groundcover, Penstemon, Red Hot Poker, Salvia May Night, Homestead verbena, Veronica Sunny Border Blue, and yarrows.

I have a cottage garden, and on the west side of the house, most of the perennials and shrubs have distorted, shriveled leaves on the perimeter of the branches. What could cause this?
Distortion of leaf tips and dieback could be caused by the drift of a chemical used for the control of broadleaf weeds called 2-4-D. On the west side of the house, the south or southwest winds could carry the chemical from the next door neighbor's yard if sprayed on a windy day. It will not kill the plants. Also, until young tender leaves become acclimated to the hot summer sun, especially next to the hot siding, brick or stucco of the west wall of the house, leaf burn can occur, but usually will not be seen only on the tips of branches. In both cases, simply pinch back leaves that are damaged and remove.

Can blueberry bushes take full sun here in Tulsa?
Yes, blueberries planted in well-drained acidic soil with proper moisture and two to three inches of mulch will take full sun or the hot afternoon sun. A great mulch to use is wood shavings that are light in color and that reflect the hot rays of the sun from the roots. Plant bushes in loose soil amended with one part peat moss to four parts soil. Water as needed to prevent soil from totally drying out.

Mark Your Calendar

Hidden Treasures in Tulsa.  Showcase garden tour of six MG gardens, June 25 & 26.

Tulsa Blooms!  Watch for this community beautification announcement on June 10.

Ask a Master Gardener.  Master Gardeners will be at Sanders Nursery on Saturday, June 5, to answer your lawn and garden questions.

4 Ways to
Contact Us

us at:
See our website at:
Call: 746-3701 from 9-4,
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.

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June Lawn and Garden Tips
  • Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk and remove the least desirable leader as soon as it is noticed. Just click link here and below for moreinformation. (HLA-6415)
  • Remain alert for insect damage. Add spider mites to the list. Foliage of most plants becomes pale and speckled; juniper foliage turns a pale yellowish color. Shake a branch over white paper and watch for tiny specks that crawl. Watch for 1st generation fall webworm. (EPP-7306)
  • Pine needle disease treatments are needed again in mid-June. (EPP-7618)
  • Cultivate and mulch. Mulching will reduce about 70 percent of your summer landscape maintenance.
  • Fertilize warm season grasses as per April instructions.
  • Dollar spot disease of lawns can first become visible in mid-May. Make certain fertilizer applications have been adequate before applying a fungicide. (EPP-7658)
  • Seeding of warm-season grasses should be completed by the end of June to reduce winter kill losses. (HLA-6419)
  • Brown patch disease of cool-season grasses can be a problem. (HLA-6420)
  • Meet water requirements of turf. (HLA-6420)
  • Post-emergent control of crabgrass and summer annual grasses is best performed on young crabgrass plants. (HLA-6421)
  • Continue to water deeply as needed. It's best to water less often, but for longer periods.  Water your lawn in the early morning, not late afternoon or evening.
  • Softwood cuttings from new growth of many shrubs will root if propagated in a moist shady spot.

Master Gardener's Showcase Garden Tour:  Hidden Treasures of Tulsa
Enjoy a self guided tour of five Master Gardener's private gardens and the OSU Extension office demonstration gardens.
Saturday, June 26th 9:00am - 5:00pm
Sunday, June 27th 11:00am to 5:00pm

The "Hidden Treasures of Tulsa" cover a range of themes:

Master Gardeners will be available at the OSU Extension Office to hand out fact sheets. They will host presentations during the heat of the day, giving visitors the opportunity to relax in the air conditioned lecture hall. The presentations each day will be on:
Safe Sex in the Garden
The Buzz about Bees
Dealing with Tomato Problems
Gardening for Butterflies
Lecture Schedule

Tickets are available at OSU Extension Office for $5.00 each. Tickets may also be purchased daily at each of the Gardens for $7.50.

Beautiful, Care-Free Crapemyrtles (Lagerstroemia indica)
If you are still looking to enhance the beauty of your garden with out-standing colors, plants shaped to your liking, along with very little maintenance, consider Crapemyrtles.



Over the past dozen years there have been many new varieties developed. They feature new sizes as well as many new colors that will bring care-free beauty to any type of landscape. You can find them now in many sizes, plants small enough for hanging baskets (12"-16"), dwarf sizes (2' to 3'),larger shrubs (4'-10') and finally, the long available tree sizes that grow to 30'.


Colors cover the spectrum, including white, pink, purple and dark, brilliant reds. Remember, if you have carefully select the right height for the spot in your landscape, it will not be necessary for major pruning every year. However,  if you need to control height or shape, they respond well to pruning. Crapemyrtles love the sun and have very few pest or disease problems.With the proper use of mulch, they should withstand our winters since they are hardy in Zone 7-9. Properly mulched, even if top branches freeze, the roots will often survive.  


Now is an excellent time to get these plants in the ground for mid to late summer blooming.


Click here for more information.

Treating Yellow Needles on Pines 

This spring, you may have noticed pine trees in the area that have yellowing pine needles. There are several causes.


Yellow needles in spring may be due to a fungus, Sphaeropsis or Diplodia, commonly called "tip blight". It appears in late May in new needles at the tips of lower limbs of Austrian, Ponderosa, Mugho and Scotch pines. The needles leak sap, develop fungal spores and die. It may cause stunting, and if it recurs yearly, kill the tree.


Another fungal disease, Dothistroma needle blight, infects pine needles during the previous growing season; the needles die in the winter and may be shed in the spring. It may cause significant damage in lower limbs of several pines.


The recommended treatment of these two fungal diseases is a fungicide. A good choice is a copper preparation called Bordeaux's mixture. It should be sprayed once in mid-May and again in mid-June to July for control.


Yellow needles may also be a result of exposure to cold winter winds. This is not limited to pine tips and may only involve the side of the tree exposed to the weather. This is usually self correcting.


If entire limbs or the whole tree yellows and dies during the late summer or winter, the tree may have pine wilt disease. This is most common in imported pines. It is caused by a microscopic worm called a nematode and is spread by pine sawyer beetles. The dead limbs are brittle, contain very little sap and may have a bluish discoloration of the interior wood. There is no practical treatment for this problem. The trees are very infectious to other susceptible pines and should be removed and destroyed.


If a valuable pine tree with yellow needles does not have a clear-cut cause, consider consulting an arborist who is ISA certified to help with diagnosis and treatment of these disorders. Click here for an informative flow chart that will help you diagnose pine tree diseases. Click here for a printable summary of common pine problems.

Need more information?
Click on any of the links below
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.
Trade names and where to find them   
How to Plant a Tree in Oklahoma Soil
Show and tell.
Landscaping and Gardening for Butterflies
How to attract butterflies to your garden 
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 2010.  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.