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Johnson County

Research-based Information You Can Trust — Localized for your needs

Johnson County
11811 S. Sunset Drive
Suite 1500
Olathe, KS 66061

Office Hours:

Monday - Friday,
8:30 a.m. - 5 p.m.

(913) 715-7000
(913) 715-7005 fax

Map to our office

K-State Research and Extension is committed to making its services, activities and programs accessible to all participants. Reasonable accommodations for persons with disabilities may be requested by contacting Johnson County Extension at (913)715-7000. Notify staff of accommodation needs as early as possible.

Kansas State University Agricultural Experiment Station and Cooperative Extension Service

K-State Research and Extension is an equal opportunity provider and employer.

Frequently Asked Lawn and Garden Questions


Fertilizing and weed control on lawns:

Tending the lawn can be confusing because of much conflicting information. I am most confused about spring fertilization and broadleaf weed control. I hear commercials for dandelion control and an application of fertilizer in the late spring. County Extension recommends fall dandelion control and very little or no spring fertilizer. When should fertilizer and weed control be applied to lawns.


That is not an easy question to answer. Research-based findings on this subject are available, but not everyone reads, believes or follows research findings. Many homeowners are still fertilizing in the spring and summer, which can increase disease and insect problems and reduce drought tolerance. Spring fertilization also results in the need to mow frequently while providing little benefit in developing a strong root system. September and November are the optimum months for fertilizing a tall fescue or bluegrass lawn. These grasses should be fertilized in the spring or summer only if they will be watered and mowed regularly throughout the summer.

Dandelions are best controlled in the fall from mid-October through early November when the weeds are small seedlings and easier to control. Unfortunately, many homeowners do not think about controlling dandelions until they see them in the spring. This is the same time when retailers are promoting herbicide sales. Control in the spring is more difficult once the plants reach the flowering stage. There is also more risk to non-target plants with spring applications of herbicides.

Nutgrass (watergrass, nutsedge) - Control of:

My lawn has come back stronger than I thought it would after the heat and drought of last summer. However, I am noticing more nutgrass then ever. What is the best way to eradicate this pesky weed?


There are many names for nutgrass including watergrass and nutsedge. This weed is a sedge and is completely different from our more common grassy and broadleaf weeds. The products that control grassy and broadleaf weeds are not effective on nutgrass. The best chemical control of sedges is a product named Sedge Hammer. Read and follow label instructions for best results. Small patches of nutsedge can be controlled by hand removal. It will take several years of pulling, but eventually the plants will become weakened and die out.

Return to Frequently Asked Lawn and Garden Questions

K-State Research and Extension Johnson County Master Gardener logo

Have questions? The Garden Hotline is staffed by trained EMG volunteers and Extension staff who will assist you with questions.

Phone: (913) 715-7050

Email: garden.help@jocogov.org