How to “summerize” your lawn with fertilizer


You may have heard of “winterizer” lawn fertilizer, but ‘summerizer”??  Yes!!  In fact, the same formula applies.  In late fall, we recommend applying a low rate of fast release nitrogen fertilizer in the ratio of 4-1-4 or 5-0-5.  The nutrients can vary slightly with each manufacturer, but should basically be in a ratio that delivers about as much potassium as nitrogen.

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Why nitrogen and potassium?  Nitrogen delivers shoot and root growth, while potassium aids in stress tolerance for cool season lawns such as perennial ryegrass, Kentucky bluegrass and tall fescue.  There are many similarities with summer and winter in regards to stress.  In winter, cold winter winds can dry out a grass plant’s crown.  Summer heat can do the same.  If slow release nitrogen is applied in early June, it will encourage an even greening effect with the shoot and leaf growth, while bolstering the root zone.  The potassium portion of the ratio will help prevent summer stress on the plants by keeping the crown hydrated and fully functioning.

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So, load up for the summer.  Apply 3/4 to one pound of actual nitrogen per 1,000 sq. ft.  If you apply the summerizer formula, the same amount of potassium will be applied at the same time.  This application should be all that is necessary on most cool season lawns for the summer. Most summerizer products contain a blend of fast and slow release nitrogen, which will provide for the long term needs of the lawn as well as some early summer benefit as well.


In late August or early September, apply fertilizer again.  In fact, in case you were wondering, here’s a handy chart for when to fertilize your bluegrass, ryegrass or fescue lawn.  It’s easy to remember, because they’re all holidays:

Holiday – Memorial Day – late May, early June       Summerizer

Holiday – Labor Day – late August, early September

Holiday – Halloween – late October, early November Winterizer

Holiday – Arbor Day – mid to late April

John Fech
Horticulture Extension Educator at Nebraska Extension
John Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of 2 books and over 200 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems and encouraging effective bilingual communication in the green industry. He works extensively with the media to extend the message of landscape sustainability, making over 100 television and radio appearances each year.
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