getting rid of hawkweed with fireplace ash

Hi,

I'm new to this list so I'm glad to pick the brains of everyone.

I bought my first house a year ago. I knew the back yard was a mess because most of it was dug up the summer of 2011 to put in a new septic system. Last summer I noticed patches of a weed I'd never seen before through my backyard. I now know it's hawkweed. I tried to smother the patches by covering them with black plastic and then overseeded it with grass.

Those patches are now grass, but meanwhile it's spread widely over the course of a very mild winter. However, it didn't spread in areas I fertilized with fireplace ash last fall, in fact it looks to be dying there. So a week or so ago, I took a couple of buckets of ash I'd been saving over the winter and put a thorough top coat of ash on the new patches. I'm hoping this works.

Anyone else ever try eliminating hawkweed with fireplace ash?

Is it possible that the alkaline of the ash is counteracting the acidity of the soil?

I'd love to know what others think.

Barbara in central Massachusetts

PS I'll post some pics tomorrow.

Update: Well, the hawkweed hasn't died, but grass is sprouting up in the middle fo the hawkweed patches. I'll make sure to lime and feed when I reseed these patches.

Update #2: Yeah, this experiment was a failure. Either it's all the rain or the hawkweed LOVES being fertilized with ash or both because it's happy and spreading. Ugh. I'll have to hoe it up before it flowers.