Lawn Fertilizers

Synthetic vs. Natural

The nutrients of most lawn fertilizers on the market today are synthesized rather than derived from natural plant or animal matter. They are packaged as liquids or powders to dissolve in water, or as granular products. While many are quick-acting because they dissolve in water, manufacturers have developed technology to coat nitrogen so that it is water insoluble and is released slowly into the soil environment similar to the way nitrogen from natural or organic sources is.

However, we have learned that even with the slow release mechanism, the chemicals in the synthetic fertililzers are harmful to the microbes in soil that are essential to the health of that soil. 

So We Go Natural in the Tool Shed
Natural fertilizers come the closest to replicating the natural nutrient processes of the soil itself. They come in “granular” or solid form or in “liquid” form. The liquid products are not recommended for lawns. The granular natural lawn products are by their nature slow-acting, because they depend on microbial action in the soil to release their nutrients for the plant roots. This feature protects the soil and its life and serves the plants better. That is why we offer product information only on natural lawn fertilizer products.

To learn about fertilizer spreaders go to Hand Tools For Spreading in Tool Shed.


It must be spring because the stacks of fertilizer, weed and feed products, herbicides, and grass seed now occupy prominent space in home centers and garden centers around Detroit.  I have noticed that for every stack of straight fertilizer, there are often three or four stacks of the weed and feed stuff; fertilizers combined with granular herbicide.  Smart retailers stock what their customers want, so people must love their weed and feed. 


Did you ever wonder, after using a weed and feed product last year, why you have weeds again this year?  Maybe the weed and feed product line is not the best way to get rid of weeds in our lawn for good.


Many of the weed and feed products contain an herbicide called 2,4-D; which is short for a unpronounceable chemical name.  2,4-D herbicide has been available to consumers since 1948. We must love it because Americans put over 10 million pounds of 2,4-D on their lawns every year. How can we spread so much material that kills weeds and still have so many weeds needing further attention?


I think there are two reasons for this puzzlement. 


First, weed and feed products are an inefficient way to kill all the weeds in the lawn. 

·      The majority of weed and feeds are granular products, spread on the lawn with a (drop)spreader or rotary spreader.  In order for the weed to die, the herbicide granules must stick on the leaves for at least 48 hours.  You must water the lawn to get the weeds wet, however if the weeds dry out too quickly, say from a breeze, some of the granules will fall off, reducing the product’s effectiveness.

·      Some folks make the mistake of mowing the lawn just before adding the weed and feed product; bad idea.  The herbicide needs to attach itself to as much leaf surface as possible to be effective at all. 

·      Weed and feed products are very often applied too early in the season.  Most contact herbicides are not effective before the average daytime temperature is 60 degrees.  In Metro Detroit, that kind of weather doesn’t arrive much before late May. Get out there too early and the weeds are still pretty much dormant.  They need to be actively growing for the herbicide to work. 

·      If it rains within 48 hours of applying a weed and feed, the herbicide is washed off and the weeds may look ratty but they are not killed. 

·      Weed and feed products are usually unable to kill some of the tougher common weeds such as clover and creeping Charlie.

·      Finally, the weed and feed products do not kill grassy weeds such as crabgrass. You have to apply a separate pre-emergent herbicide designed to prevent the seeds of grassy weeds from germinating.  The Catch 22 is that after using that product you must wait two to three months to plant new grass to fill in the space created by the weed and feed.  Two months is enough time for new weeds to occupy your lawn.


My second observation is few yardeners apparently realize that when a weed is killed, it leaves a space in the lawn.  They figure the fertilizer will make the grass plants reproduce faster and fill in that space.  That is unfortunately a bad assumption in most lawns. 

·      A lawn that is predominantly Kentucky bluegrass is reputed to fill in empty spaces rapidly, but “rapidly” is a relative term.  According to Kevin Frank, turf specialist with the MSU Department of Crop and Soil Sciences, “a bare area the size of a silver dollar will fill in after a week or two.  However, a space the size of a softball or larger will need to be seeded with grass seed to avoid the re-entry of weeds”. 

·      Many lawns in the Detroit metro area are not predominantly Kentucky bluegrass.  They have a mixture of that species plus some perennial ryegrass and fine fescues.  Those latter species do not fill in space as rapidly as the Kentucky bluegrass. 


The bottom line – if you kill weeds with a weed and feed product and those dead weeds leave spaces larger than a softball, you need to over seed those areas if you want to break the habit of having to apply a weed and feed product to your lawn every spring. 




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