Fertilizer shelf life

I have used the same lawn fertilizer applied at the same time for years. I use Scott's Turfbuilder with Halts and it has been very effective controlling weeds and dandelions.

Early this spring I was in a hardware store and they had it for sale half price. The guy at the register said it was leftover from last year. Thinking that fertilizer didn't pay much attention to the calender I thought I would save a few bucks. I put it down in March and now I have crabgrass springing up all over my lawn.

Does anyone know if the herbicide in the fertilizer loses it's effectiveness over time?

 

I believe the primary herbicide in Halts is Pendimethalin which generally has a long shelf life - up to 10 years. However, that's assuming the product was stored properly. Even in Scotts packaging, the product could have been in a very damp and/or hot location. If so, shelf life could have been reduced considerably.

 

Where are you located? I think the culprit may be when and how you applied it. Many parts of the country warmed early this season so a pre emergent crabgrass controller should have gone down early. And on the same note this is the time when crabgrass starts growing so it may be early to tell if you have control.

 

I think that you may be right. We had a strange winter this year. Very little snowfall and unusual temperature swings.

I only fertilize my lawn - about 7000-8000 s/f. The rest of my yard is old cow pasture that I keep mowed but don't otherwise maintain. It has lots of weeds including crabgrass, dandelions and buttercups.

My lawn seldom has any of those. Today when I mowed I noticed that while I had some crabgrass, I did not have any dandelion or other weeds.

My guess is that I may have been a bit late to prevent the crabgrass from germinating. But I don't think that I'll buy bargain fertilizer again.