Don't forget fertilizing as weather cools off

Granular fertilizers can be applied with a drop spreader or a broadcast spreader as pictured.

Applying fertilizer is one of the most important procedures done as far as lawn care goes, as it influences grass color, helps it deal with stress and prevents weed invasion and disease.

Two important factors to consider when applying a fertilizer are when and how much. Use Labor Day and Halloween as a guideline for the appropriate times to apply fertilizer in the fall. Fall fertilization has been proven to be the best time for application as it helps to produce the healthiest turf throughout the year. Some of the benefits of fertilizing in the fall are that you will have a lengthened period of green, you will have an earlier green-up in the spring without the excessive top-growth and the energy that is stored in the plant and available for growth remains higher throughout the spring and summer thus resulting in a reduced incidence of summer disease occurrence. Some sources recommend a spring application of fertilizer around the beginning to middle of May, say about Mother’s Day.

Nitrogen (N), phosphorus (P) and potassium (K) are the three major nutrients needed by grass. Nitrogen gives the grass its deep, rich color and promotes vigorous growth. Potassium builds strong roots, and phosphorus is important in stimulating early root growth and promoting plant vigor. It is recommended to obtain a soil test before applying a lawn fertilizer so you can determine what mineral elements your soil needs. There are two types of nitrogen, quick release (soluble) and slow release (insoluble). A good turf fertilizer will contain some of both. The slow release will provide nitrogen over a period of time but is not available to the plant during cool weather. The fast release will provide nitrogen almost immediately after application and during cool weather. To avoid fertilizer burn, do not apply more than 1 1/2 pounds of actual nitrogen per 1,000 square feet at one time, spread it evenly, apply when foliage is dry and then water it in after you have applied it.

It is recommended that shady lawns should be fertilized at about half the recommended rate because shaded grass grows slower and does not need as much nitrogen as grass located in a sunny area does.

Return your grass clippings to the lawn. It’s free fertilizer! Grass clippings contain valuable nutrients that can generate up to 25% of your lawn’s total fertilizer needs. In years past, it was recommended to set the mower blade down and cut the grass short for the final mowing in the fall. This is no longer recommended. Why? Photosynthesis is high during the fall even with the cooler temperatures. The higher the photosynthesis, the more energy the plant will store over the winter and into spring thus producing a healthier grass plant. Mowing off more of the grass blade will result in reduced photosynthetic capacity which will reduce energy storage and a decrease in plant performance the next summer.

Have you ever noticed the increase in the growth of your grass after a plentiful rain compared to the rate of growth using a sprinkler and groundwater? Rain water is high in nitrogen, which is essential to the greening and growth of grass. Rain water from a thunderstorm has the highest amount of nitrogen because lightning fixes nitrogen in the falling rain. Water is essential to all plants as a medium in which the plant can dissolve the minerals it needs from the soil. The issue with groundwater is that it often contains dissolved salts that can interfere with the plants ability to dissolve the stuff it needs.

One last thing: mulch those tree leaves. Layers of tree leaves can smother and kill the grass beneath it this fall. Layers of tree leaves can also contribute to snow mold, a winter turf disease. Mulching leaves with a mower is much easier than raking, blowing or vacuuming them. Regularly mowing them in the fall will cut them into small pieces that will then filter into the turf.

As always, happy gardening!

Karen Weiland is an advanced Master Gardener. More information about gardening and related subjects is available online at hort.purdue.edu/ext/garden_pubs.html. The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County, 636-2111 in Noble County, 925-2562 in DeKalb County and 668-1000 in Steuben County.

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