Ask Mr. Smarty Plants

If you haven't already checked this category in the Lady Bird Johnson Wildflower Center Plant Database, click on Mr. Smarty Plants on the upper right side of the screen and type into the Search by Keywords space "Ground covers for shade in NY".  This will bring up a number of questions and answers to topics like yours.  You can get useful tips from some of these.   With respect to your need to know how to proceed with the plants you finally choose, I suggest that you click on How To articles on the Plant Database page and consult "Caring for your new native plants" and "Gardening timeline". 

Not knowing which species you have picked out, I cannot offer specific advice.  Some species can be planted in the fall while others would be better started in the spring.  I suggest that you consult experts in one of your local plant nurseries. They can give you the information you need for your particular site.  And they can inform you as to whether rooted plant or seeds are your best option for getting started.  If seeds are appropriate the supplier often indicates the optimal number of seeds to sow per square foot.

Before talking with suppliers it would be well to type the common or botanical name of each plant you have chosen into the Plant Database and read the description that appears.  You will often find good advice there regarding the planting and care of the species.

You are setting out on a very exciting experience with native plants.  I feel certain that you will find it rewarding.