Gardening With Tony
Retaining Walls Make Level Ground
By Tony Tomeo
Jun 14, 2013 - 11:09:49 AM

Light pink zonal geranium flowers shine.
Gardening on level ground is simply easier than gardening on a slope. Soil does not erode so much. Water does not flow away. Seeds stay where they are sown.

Retaining walls are often used to level out sloped areas, or to add variations of elevation to areas that are already level. They can be made of redwood, brick, concrete block or stone. Actually, they can be made of railroad ties, unsightly old tires or just about anything that stays put. Broken concrete is presently a trendy material for retaining walls. It can be cemented or stacked loosely.

In most municipalities, retaining walls that are taller than three feet require building permits. There often required setbacks (clearance) from driveways, roadways and sidewalks. Of course, home owners associations have even more limitations.

Furthermore, retaining walls should not hold soil up against walls or fences that will rot. (Although the bottom horizontal 'kickboard' of a fence is often considered to be expendable and replaceable). Vents or utility access of any kind must not be buried. Retaining walls should not elevate the grade over large portions of root zones (where roots are dispersed) of mature trees, and should most certainly not hold soil up against tree trunks. Trees should not be planted close enough to displace retaining walls as the trees grow.

The simplest retaining walls are just rows of stone or brick less than a foot high. Since they do not hold much soil back, they are quite stable even without much engineering. Higher retaining walls have more potential for problems, particularly where dense soil is likely to slump when it gets saturated. Concrete block that is made for retaining walls is designed to fit together with rimmed undersides that limit lateral displacement, as well as hold each row of block in a setback position, so that the wall leans inward for stability.

Highlight: Zonal Geranium

While I was in junior high school, I found my first zonal geranium, Pelargonium X hortorum, uprooted and discarded in a neighborhood compost pile. Since it was too mutilated to salvage entirely, I took only two small cuttings. That pair of cuttings grew well into fluffy plants that soon needed to be trimmed. The scraps from trimming made more nice cuttings, which likewise grew into happy new plants that soon needed trimming.

Now I know why the original plant was discarded. That particular primitive type of zonal geranium is just so easy to grow and propagate that it can easily get too abundant. I have taken pieces of it with me to every home I have lived in since then. Even though I never really liked the bright pink flowers, it still grows in my garden thirty five years later.

More than five hundred modern varieties of zonal geranium are not quite so weedy or prolific, but nonetheless, are reasonably easy to propagate from cuttings left out for a few days to allow the cut ends to dry slightly (to avoid rot). They also stay more compact, less than three feet high and wide, and have bigger and fluffier flower trusses. The white, pink, red, pastel orange or nearly purple flowers bloom mostly through warm weather, but can continue sporadically through winter. The scalloped and rounded leaves often have slightly darker mid-zones.

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