At present, there is a strip of land 14″ by 70′ along the lot line between my property and that of my neighbour. While the strip runs north to south, it receives only 45 minutes of sunlight because of the closeness of the two houses except for the portion that runs from the city sidewalk to the front of the houses. On one side, there is a patterned concrete walkway while on the other side is interlocking brick.
My neighbour and I wish to plant something that will crowd out and keep out the violets and a variety of other weeds without creating their own myriad of seeds or rhizomes that may do damage to the bricks or patterned concrete.
For the portion between the houses, we considering of a variety of hostas, but are concerned that the spreading leaves will encumber the walkways. While smaller leaf dwarf varieties are available, will they provide enough ground shade to suppress the violets? Alternatively, will the roots of Pachysandra (Japanese Spurge) disrupt the interlock bricks.
We are also concerned at to the effect of the limestone screenings and limestone gravel beneath the walkways. Although the walkways are about 12 years old, will the leaching of waters (pH) from these areas be detrimental to the viability of the plants? Thanks!
You may want to dig out and compost the soil that is in the strip of property where you are trying to create a new bed. This area may have rocks or extra limestone screenings from the installation of the concrete or the interlocking brick. It may also be a poor quality soil that might not be ideal for your new plants. I like to recommend digging out the area to a depth of about 12 inches and lining it with newspaper (about 10 sheets thick). This creates a nice temporary barrier to the surrounding soil and will allow your new plants time to get their roots well established. The newspaper will eventually breakdown and provide some added organic matter to the bed. Then fill the bed with good quality soil, e.g. triple mix. Covering the soil with a layer of mulch will also help to suppress any weed seed growth and makes the removal of any that do grow that much easier. The amount of leaching that will occur sideways from the walkways should be minimal and your plants should be able to adapt to it.
As for the choice of groundcover, you might want to choose something that is more clump forming such as hosta rather than a spreader like pachysandra so that you don’t have to worry about unwanted plants spreading into the cracks between the pavers of the interlock. There are some “spreaders” that do however have roots that are easily pulled out in order to control their spread. Whatever plant you choose, you should check the spacing on the information tag which will give you a good idea of the mature size so that you can stay within the bounds of the bed without spilling onto the paths.
Some additional good groundcovers to consider are barrenwort (Epimedium cv.), deadnettle (Lamium maculatum), sweet woodruff (Galium odoratum), big-root cranesbill (Geranium macrorrhizum), lungwort (Pulmonaria saccharata) and foamflower (Tiarella spp.).