Ask the Determined Gardener

How can I get rid of sandburs?

Sandbur is a summer annual grassy weed. Apply a preemergence grassy weed treatment 2 weeks before germination. Check label info for specific times and application rates. In May or June apply postemergence organic arsenicals such as AMA, DSMA OR Crabgrass Killer Formula II. To control sandburs in pasture, Plateau and Pastora are recommended. Sanitation is a great help in controlling this weed. At first mowing, if you have a bad infestation, bag and dispose of clippings. You may be able to spot treat or dig up individual plants. Diligence is important to eliminate sand burs from your lawn.

When do I plant my potatoes and onions?

In Oklahoma, plant your hardened potato slips (cut with at least one eye and allowed to dry until cut surfaces are dry to the touch) between Feb. 15 and March 10. A planting depth of four inches with spacing one foot apart will give you good performance. Red, white, yellow and russet varieties are available. Onion sets or plants may be planted between Feb. 15 and March 10. Plant both types one inch deep with four inch spacing. Onion sets are better for harvesting green onions. Research your particular variety for cultivation methods. Do not step on or break over tops; onions are ready to harvest when the tops die back naturally. You may need to remove flower stalks as they appear so all the growth will go to a better onion head.

How do I take a soil sample and where do I send it?

A soil sample should be taken for each use of your beds, vegetables, roses, flowers, shrubbery and turf grass. Collect, in a plastic bucket, 12 to 16 samples throughout the area you are wanting tested. Take samples from 6 inches deep to eliminate thatch or roots. A small sampling from each location works best. Mix samples in plastic bucket (to eliminate metal contaminants), remove stems, roots rocks and other hard debris. The amount needed may vary but a 1 quart baggie should be enough material. Bring your sample to your County Extension Office. Fill out the proper forms for what you want to grow. Analysis cost is $10 per sample and takes about two weeks to get results back. You will be advised of any adjustments needed and the appropriate rates of application for Nitrogen, Phosphate and Potassium. Other testing may be done for an additional charge. This will usually be by 100 square feet areas; you may need to adjust for your garden size. The Extension Office will have literature to adjust for your area. It may take a few years to fully correct your soil for the crop you are growing.

How do I control white grubs in my lawn?

White grubs, the larval stage of June beetles are active from April through August. They are highly concentrated under bright street lights. If you can lift the sod by hand, grubs have probably eaten the root area of your grass. Treatment is most effective from April 1 to mid-May or from August to September. Carbaryl is the common name for an effective treatment; Garden Tech Sevin Concentrate Bug Killer is the brand name of this foliar spray. Read label for treatment directions. Several crystal products are designated for grub control. Bayer Advanced Grub Killer Plus is one of several on the market. These are broadcast products to spread over affected areas. Read labels for treatment instructions. You can obtain fact sheet 7306 and 6420 on line at

For more information , please visit our website at or contact the OSU Extension Service at 405-713-1125.