Question
I have a area of lawn that is doing very poorly.  It is full of thistles and moss. (I did spot applications of round up on the thistles recently)The soil is very heavy with clay.  It is on the top of a hill, is not shaded.  

This area has never been fertilized, and it is not in an area we can easily water.  (also we have water issues and have to truck in water in the summer for our horses) last year I mowed it regularly.

We live in central ontario, so it is just greening up now.  Please help =o)

Answer
Kerri,

I think you may have answered your own question.  To be honest with you it sounds like you need to make a nice flower bed out of this area.  The reason you probably have weeds and thin spots is beacuse your grass did not have fertilizer and water last year.  I dont care what you try to grow, it's hard to do without food and water.  How long would your horses last without the two?  

Round-up will kill any grass you spray it with no matter what time of year.  Unless you live in more tropic areas and are dealing with Bermudagrass which will actually go dormant during the winter, but with you being in Ontario, I would be suprised if you had bermudagrass.

Now that we know the problems, lets try to find solutions.  First dont spot spray with Round-up in areas where you want grass to grow, if you mess up and get any on the grass it will kill it.  There are plenty of products on the market that will take out thistles and not lawn grass, just read the label to make sure your type of grass is safe.  Honestly, one of the cheapest and most effective ways to control weeds is by hand removal.  If you spend a few hours pulling thistles now, before they go to seed, you will probably take care of them for this year and they should not be as abundant next year.  Even if you cant get them before they throw seeds it is still a cheap and effective means of controlling the ones you have this year.    

Moss is a tough one.  I would think that it would die this summer.  If not, about the only way to chemicaly control moss is with a product called QuickSilver.  Like I said, its the only one on the market that works and it is exspensive.  However, as I said, I would be suprised if the rest of the grass does not 'choke' it out this summer.

Lastly, seed the thin areas, water as much as possible and apply a slow release fertilizer when you plant the seed.  Preferably something with more Phosphorus in it.

Hope this helps.  Good luck!

turfnut2