Your erosion control plant roots need to reach different depths based on what type of erosion you face on your property. Surface erosion from rain splash needs roots in the top foot of soil. Deep gully erosion needs roots that reach down three feet or more to anchor everything in place. The answer depends on what problem you are trying to solve.
In my experience testing these plants, I dug up several at different ages to look below ground. A two-year-old Switchgrass plant had roots reaching over six feet deep while the top growth stood just three feet tall. The root mass surprised me. You cannot tell what lurks below just by looking at the leaves and stems above ground.
Surface erosion happens when rain hits bare soil and splashes particles loose on your property. The fibrous root depth erosion control needs stays in the top 12-18 inches of soil for this problem. Fine roots weave through this zone and bind soil particles into clumps that resist washing away when water flows across your yard.
Grasses excel at this type of surface protection for your property. A single grass plant produces hundreds of feet of fine roots that spread out like a net in the upper soil layers. These roots grab soil particles from every direction and hold them together through the heavy storms that cause the most damage.
Deeper erosion problems on your property need deep root erosion plants that reach beyond three feet into the ground. Steep slopes and areas where water collects into channels need this extra anchoring strength to stay stable. The roots hold the entire soil mass together rather than just protecting the surface layer.
Some plants send roots far deeper than you might expect when you look at them from above. Switchgrass reaches 10 feet deep in good soil conditions with enough moisture. Big Bluestem extends 10-12 feet down into the earth over several years of growth. These prairie grasses look modest above ground but anchor your soil at depths you cannot dig to by hand.
When I first started testing these plants, I measured root depth soil stabilization on a test plot over five years. The first year showed roots reaching two feet down into the soil. By year three, the same plants had roots at six feet deep. Year five brought roots past ten feet in the deep soil areas of my test site. Plants keep growing below ground long after they look full-grown above.
Your best approach combines plants that work at different depths in your soil profile. Use ground covers and grasses for binding the surface layer where rain first hits your property. Add deep-rooted grasses like Switchgrass and shrubs for anchoring the soil mass below the surface. This two-level approach gives you complete protection from top to bottom.
Space your plants so their roots will overlap when they reach full size in a few years. This creates a continuous network of roots from the surface down to the deepest layers of your soil. Gaps between root zones leave weak spots where erosion can start and spread across your slope during heavy rains.
Think about your specific erosion type before you pick plants for your problem area on your property. Gentle slopes with surface washing need dense surface roots more than deep ones. Steep banks and gullied areas need the deep anchoring that only certain species provide. Match your plants to your problem for the best results in your yard.
Read the full article: 10 Best Erosion Control Plants for Your Landscape
