Should I Fertilize In The Fall?

by Murray Anderson

There is an ongoing discussion among homeowners as to whether fall is a good time to fertilize or not. Some feel fall fertilizing is bad because it just stimulates grass and plant growth at a time of year when it isn't going to survive. However, the growing consensus among most lawn and garden experts is that fall is actually the best time to fertilize (as long as it is done properly).

Why fertilize in the fall

Think about it, your lawn has just gone through a long stressful summer so it needs food to rebuild and strengthen itself. Also, there is less competition from weeds, so fertilizing your lawn will make it thicker and more resistant to disease. As well, grass roots continue to grow even after their top growth stops and feeding your lawn in the fall, will help it develop a deep thick root system to survive during next summer's heat.

How do I fertilize properly?

Understanding the fertilizer analysis system

Most bags of lawn fertilizer have three numbers on them called the fertilizer analysis. The numbers are always in the same sequence and represent the percentage of nutrients by weight in the bag. (Nitrogen, Phosphorous and Potassium or N-P-K). Nitrogen promotes lawn blade and foliage growth; phosphorus, helps root growth as well as cold, heat and disease tolerance and potassium, promotes cell function and absorption of trace elements.
Since grass needs nitrogen all year around a fall fertilizer should contain a good percentage of nitrogen. However, since you also want to promote root growth and cold resistance, your fall fertilizer should also contain a relatively high percentage of potassium.
In October or November an application of fall/winterizing fertilizer with a percentage of nutrients in a ratio close to 1- 2- 1 would be a good choice.
You want your fertilizer to be high in potassium relative to the other nutrients, since the high potassium content will stimulate root growth just prior to winter and ensure that you have a strong healthy root system for healthy start in the spring.
Remember it's not only important to have the right percentage of ingredients in your fall fertilizer, but you need to apply it in the correct quantities as well. Always follow the manufacturers recommendations on the amount of fertilizer you put down (coverage is usually printed on the bag) or you could end up damaging your lawn rather than helping it.

What about flowers and bulbs?

In the fall, perennials start to fade and you want to make sure they have the strength to survive the long winter. Here again, applying a plant fertilizer containing a high percentage of phosphorous will give the plant roots the ability to resist the cold and grow strong and healthy. (Don't use lawn fertilizer on plants).
If you're planting bulbs, ensuring they have lots of phosphorous will give you strong, healthy flowers next spring. Some natural fertilizers such as bone meal do contain high percentage of phosphorus, however, they can also attract animals that will eat both the bone meal and the bulb. So it's probably better to stick with a chemical fertilizer for your bulbs.

Murray Anderson is an experienced freelance writer over 500 articles published on the web as well as in print magazines and newspapers in both the United States and Canada. He writes on a wide range of topics and is a regular contributor to DoItYourself.com. He can be contacted at murand@lycos.com.