Ask Mr. Smarty Plants

There are a few more details about your situation that would be helpful in zeroing in on the right plants.  Whether your garden is in a rural or more suburban setting will affect plant choice (i.e. the "wildness" factor) as well as soil and light exposure. For example, conditions on a north facing slope in an area where there is clay soil are very different from those on a south facing slope with sandy soil.

So the final plant selection will be up to you but we can help you with some guidelines.  You are already  part way there knowing that what you need are plants that spread.  Plants with fibrous root systems or that spread by stolons are what you are looking for.

The very best plants for this job are native grasses (that's why the prairies were covered with them before man came along and decided to farm, and they are generally not eaten by deer!) but there are other perennials as well as shrubs and trees (small, multi-stemmed ones are best for your situation) for you to select from so that you will end up with with not only a solid slope but an attractive garden that is part of the natural ecosystem.

If you visit our website and click on Plant Database on the Explore Plants page, you can perform a combination search for New York state after entering uyour particular conditions to narrow the search.  Armed with the plant lists it provides, you can go shopping.  Ultimately, what you plant will be what is available in your local nurseries.

Here are some choices based on personal preferences and the assumption that your location is sunny with quick draining soil (sandy because you are close to Lake Ontario).

Grasses

Bouteloua curtipendula (sideoats grama)

Panicum virgatum (switchgrass)

Schizachyrium scoparium (little bluestem)

Sporobolus heterolepis (prairie dropseed)

Perennials (not all of these really spread stoloniferously, but they are vigorous and some will also  spread by seed).  Generally speaking, any perennials that gardeners are willing to share, are probably vigorous "spreaders"! These choices are also attractive to butterflies & birds.

Coreopsis lanceolata (lanceleaf tickseed)

Echinacea purpurea (eastern purple coneflower)

Monarda fistulosa (wild bergamot)

Rudbeckia hirta (blackeyed Susan)

Solidago canadensis (Canada goldenrod)

Vernonia noveboracensis (New York ironweed)

Shrubs

Hydrangea arborescens (wild hydrangea)

(although this one cannot take too much sun)

Rhus aromatica (fragrant sumac)

Rosa carolina (Carolina rose)

(there are other native "shrub" roses to choose from as well)

Rubus idaeus ssp. strigosus (grayleaf red raspberry)

(any member of the bramble group will do, and will give you berries for your cereal as well)

Symphoricarpos albus (common snowberry)

Viburnum acerifolium (mapleleaf viburnum)

Small trees

Amelanchier laevis (Allegheny serviceberry)

Rhus typhina (staghorn sumac)

Sorbus americana (American mountain ash)

As you see, the challenge is not the erosion, it's having to choose from this list of great native plants! 

Bouteloua curtipendula

Panicum virgatum

Schizachyrium scoparium

Sporobolus heterolepis

Coreopsis lanceolata

Echinacea purpurea

Monarda fistulosa

Rudbeckia hirta

Solidago canadensis

Vernonia noveboracensis

Hydrangea arborescens

Rhus aromatica

Rosa carolina

Rubus idaeus ssp. strigosus

Symphoricarpos albus

Viburnum acerifolium

Amelanchier laevis

Rhus typhina

Sorbus americana