By Mark Saidnawey, WBZ Gardening Expert and Owner of Pemberton Farms in Cambridge, Ma

Each spring when the Forsythia show their brilliant yellow flowers it’s my reminder that it is time to feed my lawn with a lawn fertilizer that has pre-emergent herbicide control.

What Does A Pre-Emergent Control Do?

Pre-emergent herbicides are chemicals that prevent the germination of weeds in your lawn.  These herbicides control annual grass weeds like crab grass, chickweed and dandelions by inhibiting their cell division in the young root system. The failure of the root system to develop, results in the death of the young seedling weeds shortly after germination.

When Do I Apply Them?

Timing is very important.  Pre-emergent controls must be applied before the bad “weedy” seeds are allowed to germinate.  For us, here in New England, it is generally the middle of April- especially when you see those brilliant yellow flowers of the forsythia in bloom.  That is my signal.

So Which Type of Fertilizer Should I Use?

Synthetic vs Organic…

We are all familiar with those television commercials for Scott’s lawn fertilizer with crabgrass control.  This a great choice for a synthetic lawn fertilizer and is very effective the same year it is applied.  However, with the increasing desire to use only organic products in your lawn and garden, there is now a great alternative for you to consider.

Gaining in Popularity over the past few years, corn gluten meal (CGM) is a natural substitute for synthetic pre-emergent herbicides.  The use of corn gluten meal as an herbicide was actually discovered by mistake during a turfgrass disease research project conducted at Iowa State University.  Since then, CGM has been proven to prevent weeds from sprouting including seeds from many weeds such as crabgrass, chickweed, and even dandelions.  You should apply CGM the same time you would any other pre-emergent, then a second time around mid-August. Spread the product evenly, at a rate of twenty pounds per 1,000 square feet of lawn. Water it lightly into the soil to activate it. The CGM should remain effective for five to six weeks each time you apply it. 


  • Whichever type of pre-emergent crabgrass fertilizers you choose, you should apply it evenly over the entire lawn. Even if you have only noticed crabgrass in certain areas of the yard in previous years, take the time to cover the entire lawn. Spots that are skipped can allow stray crabgrass seeds to germinate, grow and spread.
  • Do not aerate your lawn after application and wait three months before reseeding any part of the lawn
  • If you are planning to over-seed on bare spots, or perhaps reseed the entire lawn, you will need to wait up to 3 months before applying new seeds as the pre-emergent will prevent any germination of new grasses.

My goal is to have my backyard look as nice as they do at Fenway Park and that requires a lawn maintenance program throughout the growing seasons.  Fertilizing up to four times is year will get you the best results but no step is more important than the first one!  If you have any specific questions you may email me at

Best of Luck.

Mark Saidnawey
WBZ Gardening Expert and Owner of Pemberton Farms

Comments (5)
  1. manowx says:

    Way to go Mark. I think I’ll pass. I’m not much for keeping up with Jones’s

    Has anyone noticed an inherent contradiction with lawns. We grow grass only for it to be cut numerous times during the course of a spring and summer. It’s almost lunacy.

    1. itoldyouso says:

      thats why your lawn is made of gravel!!! nice lawn–lmao

      1. Get a life says:

        debby downer will be your new name itoldyouso….lmao twice

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