Stabilizng Steep Banks
Hello Waterbury VT,
Attempting to stabilize a steep bank with clay soils (and a south exposure) with seed alone is not necessarily going to produce the outcome you desire. It worries me that you could actually add to bank erosion without adding additional stabilization. By adding topsoil, compost, rocks, mulch and/or other media to retain soil and moisture, your project has a better opportunity for success.
If you want to focus solely on seed then I believe ornamental grasses will help with stabilization. They tend to have more fibrous roots and they tend to spread quickly. I am offering you some Vermont native species to try out:
As noted, I feel bank stabilization is best done with a mix of plantings that include grasses, ground covers and low growing shrubs. Some additional recommendations, should you feel so inclined: Vinca minor L (Periwinkle), Arctostaphylos uva-ursi (Kinnikinnick or Bearberry), Rhus typhina (Staghorn sumac) and Rosa carolina (Carolina rose). Even if you focus these plantings on the lower portion of your banking, I think it would make a big improvement to stabilization.
If you are really feeling energetic, you can add some perennials to the mix by planting: Asclepias tuberosa (Butterflyweed), Monarda fistulosa (Wild bergamot) and Tradescantia virginiana (Virginia spiderwort).
I hope this has been helpful!
UVM Extension Master Gardener Program Volunteer
(Thanks to the LBJ Wildflower Center, TX for recommendations!)
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Thank you for your incite full response. I will review the choices you provided to me to see which grow deep roots. We have tred some of your suggestions, but mid-winter rains have undermined causing slopes to slough off, hence reason to look for deep rooted seed. We will use matting along with appropriate fertilizer.