Sunday, April 10, 2011

Grassy Weeds

I hope everyone enjoyed Garden Fest at the college yesterday.  Kim gave two presentations and I gave on on watergardening.  Next weekend we will have several seminars at the store so drop by to find out about the best new plants for 2011 and dealing with insects.

With the warmer weather I have been out looking at my lawn.  I have a bird feeder in my yard and it seems I also have a lot of grassy weeds.  I am sure there is a connection.  Neighbor Dave next door has also noticed more "crabgrass" and I had to fess up that I thought it was because of my bird feeder.  We both enjoy the birds so I guess that is a tradeoff we have to make. 

Dandelions are broadleaf weeds

It's easy to kill grass in an ornamental bed or to kill broadleaf weeds in the lawn because they are completely different in their makeup and don't react to the herbicides in the same way.  It is much harder to kill broadleaf weeds in an ornamental bed without affecting the ornamentals or to kill grassy weeds in the lawn.  One way is to get to the weeds before they germinate.  We call this preemergent weed control.  The trick to being successful at pre-emergent control is to get the herbicide down before the weeds germinate.  Most crabgrass seeds germinate when the soil temperature reaches 55F.  You need to get the herbicide down a week or two before this happens.  With our fluctuating temperatures in the spring this is hard to do.  A visual clue to timing is the forsythia.  When you see the forsythia in bloom it is time to put down the pre-emergent.  By the time the lilacs bloom, it is too late.

Corn Gluten
For those of you looking for an organic control, try corn gluten.  University studies have shown that corn gluten inhibits root development in germinating seeds.  As an added benefit it also has 9% nitrogen and makes an excellent fertilizer.  The product needs to be watered in after applying it and then needs a dry period.  Try to pick a day when no rain is forcast for the next couple of days and then gently sprinkle with a hose to get the product wet.  If it rains, the product will become too dilute and the seeds with be able to recover and continue to grow.  Apply the corn gluten at a rate of 20-40 pounds per 1000 square feet.  For best results apply twice in the spring and again in the fall.

Pre-emergent herbicides do not discriminate between "good" seeds and "bad."  If you are planning to overseed your lawn wait at least six weeks after applying the pre-emergent.  

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