Question
Hi Kenneth:
This year I am trying something new.I live in Detroit,MI  and I have mostly kentucky bluegrass in my yard. This year we have been getting a lot of rain. But what I am doing differently is I put down fertilizer in March . I used the scotts crabgrass perventer and then in May I put down the weed and feed fertilizeer I had quite a few weeds in my yard this year. My question is, is that to much fertilizer ? What I was trying this year is the scotts fertilizing program. I see my neighbors yards that have those services that come once a month and put down fertilizers and there yards look beautiful. Is all this a waste of time? Am I over fertilizing I want my yard to be green and thick. What do you think?

Answer
A cool season lawn should be fertilized in spring and fall (mostly fall) and not during hot summer months. landscapers can apply in smaller dosis which are depleted faster and thus you can not compare fertilizer packages available to home owners to the regime of a professional landscaper (also not all landscapers get it right, either).

Just because a lawn is lush and green in spring does not mean that it is healthy. A lush green lawn in early sprign can cover for a stressed lawn which is subject to problems over sommer. I recommend sticking with the recommended regime (which is different from Scott's). That gives the best long term results.

If you have had a bad infestation of crabgrass last year, then using Scott's with Halts in early spring (April) is recommended. However, if you did not have crabgrass problems, then I actually recommend skipping the application and not fertilizing until 1st half May. In May apply fertilizer (w/broadleaf weed control if you like).

Then do not fertilize again until fall. In early fall (late half august/early september) after the heat of summer, fertilize again using regular Turfbuilder and then repeat in late fall (late october/early november)

The last application of the year (november) should be AFTER the top growth stops, but before the roots go dormant. If you mow weekly in late fall then wait until you have not had to mow two weeks in a row and then fertilize. Usually between Halloween and Thanksgiving. To make it easier, I always recommend to fertilize right after Halloween in your zone even if it results in some additional mowing.
As long as the grass is green and has not been exposed to a really deep hard freeze, the roots are active and benefit from the fertilizer.


e.g.
fertilize in early April if you need to treat for crabgrass. it is better if you do not. if you have fertilized last november, that application will cover the early spring.

fertilize in mid to late May. if you fertilized in April then use a "light" application (1/2 volume)

fertilize in late august/early september (most important application of the year)

fertilize in late fall (late october/early november)


Always try to put 50% or more of the fertilizer in fall.
Never fertilize during hot summer months
Avoid too much herbicides/insecticides.

Actually, I prefer to use regular lawn fertilizers without any herbicides/pesticides. If you need to treat weeds (broadleaf, like clover, dandelions,etc) then use a product called WEED-BE-GON which comes in spray bottles. Spray in late spring or early fall when day time temperatures are below 85 deg F. Follow directions on bottle.