by David Hillock


  • Watch for fall specials at garden centers and nurseries since fall is a great time for planting many ornamentals.
  • Choose spring flowering bulbs as soon as available.
  • Plant cool-season annuals like pansies, ornamental cabbage or kale, snapdragons and dusty miller when temperatures begin to cool.
  • Watch for and control any late infestations of tree webworms.
  • Twig girdler insects should be controlled if large numbers of small branches of elms, pecans, or persimmons are uniformly girdled from the tree and fall to the ground.
  • Begin to reduce the amount of light on outside tropical houseplants by placing them under shade trees before bringing them indoors for the winter.


  • You have all of September to plant cool-season vegetables like spinach, leaf lettuce, mustard and radishes, and until the middle of September to plant rutabagas, Swiss chard, garlic and turnips.


  • Last nitrogen fertilizer application of the year on warm-season grasses should be applied no later than September 15. (HLA-6420)
  • Winter broadleaf weeds like dandelion will begin to emerge in late September, which is also the best time to control them with a 2, 4-D type herbicide.
  • If pre-emergent control of winter-annual weeds (henbit, chickweed, annual bluegrass, etc.) is desired in lawns, the application should be completed by the second week of September.  Note: Do not treat areas that will be seeded in the fall.
  • Continue bermudagrass spray program with glyphosate products for areas being converted over to tall fescue this fall.
  • Plan to seed bluegrass, fescue or ryegrass as needed in shady areas in mid- to late-September. Fall is the best time to establish cool-season lawns (HLA-6419).
  • White grub damage can become visible this month. Apply appropriate soil insecticide if white grubs are a problem (EPP-7306). Water product into soil.

A Second Crop

by David Hillock

There are several cool-season vegetables that can still be planted throughout the month of September for a fall/winter crop of fresh produce. Plant veggies that grow rapidly, such as lettuce, spinach, mustard, radish, beet, collard, Swiss chard, turnip, kohlrabi and kale. Onion, garlic and leek are also planted now, but won’t be ready to harvest until late spring to early June of next year. If you can get broccoli and cauliflower seedlings, plant those as well.

The key to survival for these cool-season plants is to keep the plants cool and moist until temperatures begin to drop. You can purchase shade cloth specifically for this purpose, or use other materials found around the house. Old window screens, scrap wood staked vertically, extra pieces of landscape fabric etc. work well in reducing temperatures and dry winds that can exhaust young plants. Grass clippings sprinkled lightly on top of young seedlings about 1/8-inch thick, cools the soil, reduces evaporation, and suppress weed seeds on the soil surface.

Twig Girdlers

by David Hillock

It is not uncommon to find small twigs lying around the yard this time of year. You may also see twigs loosely attached or lodged in the canopy of trees. This is usually an indication that twig girdlers, long-horned borers, have been actively working on your trees. Twigs look as if someone whittled the end that was attached to the tree.

Adult twig girdlers will girdle the branches before laying eggs in the twig. Apparently the larvae cannot survive in live wood. These twigs usually break off and fall to the ground or get lodged in the canopy. Larvae overwinter in the dead twig either in the tree or on the ground becoming active again in spring. Eventually they pupate, emerge as adults during August and September and then start the process all over again.

Generally twig girdler damage is not detrimental to a tree, but can result in reduced production in pecans as well as affect the beauty and aesthetic quality of ornamental trees. Besides pecan, twig girdlers are commonly found on hickory, persimmon and elm. They also attack oaks, honeylocust, hackberry, poplar, dogwood, sourwood and various fruit trees.

Insecticide treatment is usually not necessary unless there are heavy infestations that will affect fruit or nut production. The best approach for control is gathering and destroying the severed twigs during the fall, winter and spring.

Getting Fruit Crops Ready for the Fall

by Becky Carroll

There are a few things that will be helpful to prepare your fruit crops for winter.  Plants that are ready for the winter conditions will be less likely to have cold injury.

Irrigation - Start to shut down irrigation between September 1 – 15. Make sure the soil profile has sufficient water for the vines before shutting down the irrigation system. Irrigating too late into the fall will encourage growth and interfere with the natural dormancy process.

Grow Tubes on Grapes - Remove grow tubes around September 1 or at the very least, separate them from the ground.  Removal is best. They can be reinstalled in the spring if needed. Grow tubes create a microclimate that heats up during the day (warmer than ambient temperature) and then cools off at night to same as ambient temperature. This can lead to winter injury.

Blackberry Floricanes – September/October is a great time to remove spent canes because they are much easier to tell apart from primocanes.  All canes that fruited this year should be removed (in the case of floricane (spring/summer)-fruiting varieties).  Dead canes create places for insects to overwinter as well as crowding the plant so that adequate sunlight cannot reach its interior. Thinning and pruning primocanes can be done later in the winter.

Fertilizer - Do not fertilize vines after July. Fertilizer will act much in the same way as excessive irrigation. It adds to the growth of new green succulent growth that isn’t hardened off which weakens the vines and sets them up for winter injury.

Remove disease inoculum – This is a task that should be done year round but if grapes or other fruits haven’t been harvested, remove and dispose of outside the area. Any fallen leaves can be cleaned up and removed to eliminate overwintering sites for disease and insects.

Fall herbicide applications - Early fall is good time to control weeds. By using a systemic like Roundup or Poast (grass specific) you can lessen weed problems for the next season. During the fall, plants are pulling down photosynthates to the root system to prepare for winter. Using the systemic herbicides at this time helps to get the product to the root and eliminate the weed.

Order new plants early - Order plants in August or September to ensure variety choice and rootstock is available. Earlier orders ensure the best quality plants rather than getting the leftovers when ordered in late spring. Order slightly more than needed to compensate for loss. Plants can be planted in fall, but usually in late winter/early spring is best; mid- to late-February works well for most bare root plants. Request the date for shipment that works best for the planting area.

Do soil tests for next season and amend soil – Follow the guidelines in Fact Sheet PSS-2207 (How to Collect a Good Soil Sample) and submit for analysis. Amend the soil if needed for phosphorus, potassium and any pH adjustments. Most nitrogen needs can be added later after the plants have started growing.

Sunflowers – Harvesting and Roasting

by David Hillock

Harvest begins in mid-September and can run into October. A check of the flower head will indicate maturity; florets in the center of the flower disk are shriveled, heads are downturned, and a lemon yellow color is on the backside. Pull a few seeds and split them with a knife to check if seed meat has filled. Poorly filled seeds may be due to a lack of pollinating insects.

Sunflower seeds are ripe when they fall off of the head, or the birds start eating them. To prevent loss, cover the heads with a paper sack, cheesecloth or nylon netting once the yellow petals start turning brown. Secure the sack, cheesecloth or nylon netting with a rubber band or twist tie to prevent seeds from dropping. Heads can also be cut with about a foot of stem attached and hung in a warm, dry, well-ventilated, rodent and insect-free place. Cut the heads once a few seeds start turning the traditional black with white stripes. The flavor will not be as good as those ripened on the plant, but less loss will occur. Once the seed is dried, it can be rubbed easily from the seed heads. Humidity levels must be kept low to prevent spoilage. Sunflower seeds will remain viable for seven years when stored in a cool dry, dark location.

Raw mature seeds may easily be prepared at home by covering unshelled seeds with salted water (2 quarts of water to ¼ to ½ cups salt). Bring to a boil and simmer two hours or soak in a salt solution overnight. Drain and dry on absorbent paper.

Put sunflower seeds in a shallow pan in a 300 degree F oven for 30 to 40 minutes or until golden brown, stirring occasionally. Take out of oven and add one teaspoon of melted butter or margarine to one cup of seeds. Stir to coat. Put on an absorbent towel. Salt to taste.

(Sources: Ohio State University Extension Factsheet, Horticulture and Crop Science, Growing Sunflowers, HYG-1228-92; Illinois Coop. Ext. Service, Horticulture Solutions Series, Sunflowers—Harvesting)

Despite Spring Rains, Flash Drought Symptoms hit Oklahoma

by Leighona Bernstein and Justin Quetone Moss

Get to higher ground, do not drive through standing water and proceed with caution around bodies of water. These are the typical warning for flash floods, but what about flash droughts? Though not as well know, flash droughts can strike as quickly and cause just as much damage as a flash flood.

A flash drought occurs during a period of high temperatures and decreased moisture levels following heavy rainfall. Brian Fuchs, climatologist with the National Drought Mitigation Center, said what differentiates a flash drought from a regular drought is the quick onset of symptoms.

Justin Moss, assistant professor and Huffine endowed professor of turfgrass science at Oklahoma State University, said flash droughts can take a toll on home landscapes and turfgrass.

“It is very common for lawns in Oklahoma to get brown in August,” Moss said. “Stress from a flash drought can make usual issues worse, so it is important to save as much water as possible and not over-water a dormant lawn.”

Even though, according to the Oklahoma Climatological Survey, the spring rains ended Oklahoma’s chronic drought, Moss advises water conservation awareness.

“We can’t get complacent,” Moss said. “Just because we got a bunch of rain, we have to save as much as we can. This flash drought is a good reminder of that.”

Visit for more information on water conservation and drought awareness in Oklahoma.

Patio is Center of Outdoor Entertainment

by David Hillock

You can’t have a party without a party room, and, to your landscape, that “room” is the patio. Here are some tips to ensure the most successful patio possible.

It must be convenient, that is, accessible. Hopefully it will be adjacent to the kitchen, den or dining room, a short step from your home.

It should seem like the intermediary, the space between your indoor living area and the great outdoors. Folks’ eyes should be guided across it, out into the yard, to a focal point toward the back of the landscape.

t should be adequately sized. Figure 100 to 200 square feet per family member. If your current patio doesn’t have that much space, expand it. You can use pavers or flagstones or concrete squares placed against one or more edges of the existing concrete patio. Or, cover it completely as you also enlarge it by using concrete pavers or epoxy-stone surfacing.

Shade it from the hot sun. If it’s to be used primarily in the evening, plant a small shade tree a few feet away from the west edge of the patio. If it will primarily be a breakfast nook, let the shade be to the east.

You may prefer a permanent arbor. If so, build it with sturdy timbers. Use beams that are large enough to shade it well, but open enough to permit free flow of the air. Use deciduous vines to provide shade in the summer, then allow winter’s rays to reach the patio surface below.

Select quality patio furniture. First and foremost, it needs to be comfortable. It should be made to last with minimal repainting. Sit in the furniture for a while before you buy it, just to be sure it’s comfortable for long stretches.

Use striking annual flowers and tropical plants to give the patio a festive appearance. Choose handsome terra cotta patio pots, also quality hanging baskets, then fill them with showy plants.

Finish it off with quality night-lighting. Down-lighting is the most natural, giving the illusion of moonlight. Lights give your special patio an entirely different feeling at night. It’s like having two gardens for little more than the cost of one.

Follow ThinkWater on Social Media

by Leighona Bernstein and Justin Quetone Moss

ThinkWater is on social media! Follow us on Twitter @ThinkWaterOK for news and bad plant jokes. Our Instagram, thinkwaterok, gives an inside look at water conscious plant species, gardening techniques and water smart landscapes. Like us on Facebook for campaign and news updates.

Upcoming Horticulture Events

September 26, 2015; 10 AM – 4 PM
The Botanic Garden at OSU – Stillwater, OK

Tree Care Issues Conference
October 29, 2015
Wes Watkins Center – Stillwater, OK

For more information about upcoming events, please contact Stephanie Larimer at 405-744-5404 or


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