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).
TIP: Our expert gardening advisor, Kathy Bosin adds, "Fall is also a great time to add organic matter, such as compost, to your garden beds."
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. Grass roots continue to grow even after their top growth stops. Feeding your lawn in the fall helps it develop a deep thick root system to survive during next summer's heat.
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 round, a fall fertilizer should contain a good percentage of nitrogen. However, since you want to promote root growth and cold resistance, your fall fertilizer should also contain a relatively high percentage of potassium. You want to stimulate root growth just prior to winter and ensure that you have a strong healthy root system for healthy start in the spring.
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.
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 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. It's probably better to stick with a chemical fertilizer for your bulbs.