Fields of Green

Runner plants grow by creeping along or just below the surface of the substrate and producing nodes of leaves along the way, which makes most of them ideal ground cover.  Aside from their horizontal orientation, trimming runner plants is a lot like trimming stem plants.  A few example of popular runner plants are Glossostigma Elatenoides, Hairgrass, and Chain Sword.

When planting runner plants, it often helps to have a pair of tweezers handy to put individual plants into the substrate.  You will get much broader coverage out of these plants if you spread them out a bit when planting, so distribute whatever quantity you have evenly throughout the space available.

In the early stage of a ground cover, the only problem you have to worry about is runners finding their way into areas that you don’t want them too.  When that occurs, scissors or a razor blade will re-establish a boundary quickly and easily.  Simply cut in a straight line along the border that you want to establish through the mat of runners.  I recommend cutting back with some space to spare so that you don’t have to do it too often.  It also allows for a few runners to grow out of the mat and into the new space, creating an interesting and natural look.

In the middle stage of a ground cover, runners will begin to grow across each other and start to form a mesh or mat.  Maintaining a ground cover mat during the middle stage is a balancing act of keeping the mat from overgrowing itself and allowing it to get thicker.  As the mat gets thicker, older plants can get shaded by new plants growing on top of them and suffer.  To prevent this, be diligent about trimming off the overlapping plants.  If you can’t see where to cut, you can usually pull up slightly on the mat and expose a better angle at the overlapping runners.  During this stage, depending on the plant, you may also “shave” the matt, much like moss, by cutting horizontally across the surface of the map, exposing all the runners to light.  The plants will sense the new light and grow in thicker than before.   The right balance of pulling out individuals, shaving, and allowing the mat to grow will depend on the plant and is learned through experience.

Eventually, like stem plants, runner plants must be periodically pulled out of the substrate in bulk to keep them healthy.   Every plant has its tipping point where it becomes so thick that not everyone can get their share of the light, and the lower regions of the mat will decline as it traps more mulm and becomes a haven for algae.  When this occurs, the only solution is to pull the mat up, vacuum out the accumulated mulm, and replant.  Like spring cleaning, your tank will feel fresh and clean again.