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FAQs - Lawns - Management Practices - Summer


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Can you explain to me what the three numbers on every bag of fertilizer mean?

When exactly is the best time to fertilize my lawn? I have heard both the spring or the fall but I want to do the right thing.

I have a dog that I let run outside. Is it safe for me to fertilize the lawn where my dog runs?

Last summer was so hot and dry that I had to reseed a small portion of my yard because the grass died. What are your recommendations for watering lawns?

This morning I noticed reddish-pink spots in my lawn.  The grass in these areas looks  dead.  I assume this is some type of disease.  Is there a fungicide you can recommend?

Can you explain to me what the three numbers on every bag of fertilizer mean?

What you are referring to is sometimes called the guaranteed analysis or nutrient guarantee. The three numbers are separated by hyphens and represent the percent by weight of nitrogen (N), phosphorus (P) and potassium (K). Nitrogen promotes plant growth and color, phosphorus helps with root development and potassium contributes to the overall health of plants helping turf to withstand stresses such as drought or disease. Most Maryland soils have sufficient phosphorus. Soil testing will determine if applying phosphorus is necessary and should only be applied if a soil test shows that your soil is in the low to medium range.

When exactly is the best time to fertilize my lawn? I have heard both the spring or the fall but I want to do the right thing.

The type of grass that you have determines the best time to fertilize.  Cool season grasses, like tall fescue and Kentucky bluegrass, should be fertilized in the fall to help turf recover from summer stress and to promote a deeper, healthier root system. Warm season grasses like zoysia and bermudagrass should be fertilized in late-spring through early August. They go dormant in the fall and the unused fertilizer would run-off into the Bay.

I have a dog that I let run outside. Is it safe for me to fertilize the lawn where my dog runs?

Fertilizer products that contain either an herbicide or an insecticide may be harmful to pets. So when choosing a lawn fertilizer make sure that it is labeled as a fertilizer only. Always read the product label and follow any precautions listed. Granular fertilizers should be watered in. It is best to keep your dog off of the area until the lawn has thoroughly dried out after watering. Also, see the National Pesticide Information Center for information.

Last summer was so hot and dry that I had to reseed a small portion of my yard because the grass died. What are your recommendations for watering lawns?

The past couple of summers have been warmer and drier than usual stressing out many lawns. But tall fescue, the recommended type of grass for Maryland, can withstand periods of drought and recover. The grass does turn brown and goes dormant, which is normal for cool season grasses, but in most cases, greens-up again when cooler temperatures and rainfall return. However, newly seeded and young lawns or recently installed sod do need to be watered during droughty periods. Water in the early morning and apply about an inch of water to the lawn. Watering deeply, less frequently is better for root development than watering more often with less water. Unfortunately, sometimes reseeding in the fall is necessary.

This morning I noticed reddish-pink spots in my lawn. The grass in these areas looks  dead.  I assume this is some type of disease.  Is there a fungicide you can recommend?

Your turfgrass has a disease called red thread. This is a fungal disease that is confined to the grass blades but does not kill the crown. Red thread is a common disease of turfgrass during cool, wet springs. When weather patterns change the progress of the disease will stop. Red thread can occur on under fertilized lawns and also on lawns that were excessively fertilized in the spring.  We do not recommend a fungicide, but that you follow University of Maryland guidelines for fertilizing.  See our lawn maintenance calendar, (PDF) HG 112 Turfgrass Maintenance Calendars for Maryland Lawns for information on that.

Please send us a question at Ask the Experts if you have a lawn question you would like answered. Digitial photos can be attached to your question.

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