Question
The back yard of our Chappaqua property is hard clay with a slope.  The landscaper has sewed what he said was ryegrass on the slpe, rather steep. Then he covered it with straw or hay, which he said was done to protect the seed.  Just 3 days later the seeds were growing grass.  Well this was quite exciting.  Landscaper repeated this time on the flat section.  Then the slope grass died suddenly.  Now the other grass is also dieing.  No explanation from landscaper.  Do you know what my next step ought to be?

Answer
You did not mention watering this Grass, but perhaps it was an obvious detail that was omitted.  I would just like to confirm that you watered the Rye at some point, preferably a lot.  Something wet went down because the Seed germinated both times.  Just humor me.

You specify that you have 'hard Clay'.  Your landscaper did not do any test or corrective measures, probably to save time and because correcting anything would be problematic on a steep slope.  Am I right?

You should know that although Rye is a great choice for a slope, because it germinates so quickly (as you have seen), Rye is really not adapted to grow in Clay.  Although the slope will prevent a drainage problem, the Rye roots are not built to break up something almost impenetrable.  Try to run your fingers through a Clay plot and you'll see how really solid it is.  Purdue University posts a Rye sheet on its website that will tell you everything you need to know about growing it successfully -- and this is not hard to do:

www.hort.purdue.edu/newcrop/afcm/rye.html

They specifically point out that Rye 'should be planted on well prepared, fertile, well drained Soils, having a pH of 5.6 to 5.8 or higher.  Rye grows better on light loams and Sandy Soils than on heavy Clay Soils.  It is also able to germinate in relatively dry Soils, and is fairly tolerant to droughty conditions.'

And of course it also needs to be watered.  The Straw was designed to keep the Seeds from blowing away or washing off; if you water the Seed at all, or if it rains, moisture is retained to help germination.  I would also like to know what kind of other care you are giving this Lawn, as well as whether or not you have given any though to how you are going to mow the slope area (the landscaper perhaps has some idea on this?), and when.

Thanks for writing, r.s.v.p.,

THE LONG ISLAND GARDENER