Garden Notes: Go native, get wet

We cut, clear, tidy, and attempt to create new idylls. Very often the imposed, controlled landscapes unwittingly obliterate unique features and beauty — the wild gardens — that were here previously. The checkerberry and huckleberry happily growing together under oaks in dry woodland are scraped off — to be replaced by reluctant lawn, which is unhappy there and must be maintained on irrigation.

As the photo illustrates, Island natives Geranium maculatum, the wild geranium, and hay-scented fern (Dennstaedtia punctilobula) make a beautiful spring combination, one that is easy to admire: its beauty becomes its raison d’être. Shortly after the shot was taken, roadside mowing destroyed this scene; no doubt many think the roadsides look better maintained in a park-like condition (by petroleum-fueled machines.)

While wild geranium and hay-scented fern are found over a large range in eastern North America, they are a special seasonal duo that is characteristic of certain kinds of places on the Vineyard. Wild geranium, a clump-forming perennial to about a foot and a half tall with large pale pink-to-lilac flowers in airy sprays, used to be quite common about the Island’s highways and byways, but I encounter it less often nowadays. Hay-scented fern is a colonizer that grows in generous swaths, also often eradicated in favor of lawn.

Would anyone similarly admire an image of wild cherry and goldenrod, two mundane roadside plants? Yet, these “weeds” underpin the web of Island life to an astounding degree. Goldenrod supports about 115 species of butterflies and moths, while Prunus supports 456, according to Douglas W. Tallamy in “Bringing Nature Home: How You Can Sustain Wildlife with Native Plants” (Timber Press, Portland Ore., updated 2009, 358 ppg.)

In contrast, an invasive alien shrub such as autumn olive (Eleagnus umbellata) may feed adult birds with its fruit, but supports very few of the insects their nestlings require. In contrast, a wild cherry is a buffet for birds at all stages. We have limited understanding of the role and importance of commonplace vegetation and lowly life forms in supporting not only the rare and the showy but also the entire web of life.

For myself, as a human or a gardener, insect life may be exploding and pesky just now, but for birds and their young, amphibians, fish, and smaller mammals, it is indispensable food. As I have tried to demonstrate in previous columns, my own awareness about the role of commonplace vegetation and subordinate life forms has changed a lot in the last two decades.

I learned, for example, that the tree prefers to make its own fertilizer. Who are we to determine that it is mulch from the mainland that the tree needs, rather than its own leaves or needles, which are cleaned up and whisked away from under its branches, the landfill their destination?

Moisture retention in soil

We have had lengthy dry spells in April and May this year. Many homeowners and gardeners are doubtless concerned about watering. Too dry is not good; neither is too wet. The May print edition of In the Kitchen (www.inthekitchenonline.com) contains this by Terry Lilley: “The easiest and cheapest place to store water is in the soil. Rich soil acts as a sponge that can hold several times its weight in water. Organic matter in the soil is the key to moisture retention. Research has shown that soil with a two percent organic matter content can reduce the need for irrigation by 75 percent, as compared to soil with less than one percent organic matter….”

Create furrows as much on the contour as possible with either the furrowing attachment of a wheel hoe or with the onion hoe, an arrowhead-shaped tool that makes a furrow with one end and closes it over with the other. Use these sculptings to slow run-off and to distribute water or compost tea.

Speaking of watering, hoses in gardens can be agents of destruction. To prevent hoses from decapitating or breaking plants, a watering can or “mud-bucket” containing water is heavy enough to be used as a hose guide between rows or carried to different spots.

Convenient and seemingly clever as irrigation systems are, they have innate drawbacks, of which the difference between rain and irrigation is the most serious. “What is the difference?” you say, “water is water.”

Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil liquid and air. Constantly irrigated soils begin to lose their air, leading to compaction. Irrigation can also bring salts to the surface by capillary action. Steps must be taken to reintroduce air, to improve the spaces between the soil particles. It is the soil bacteria, fungi, and animals that create the spaces between the particles in topsoil, and they feed on organic matter.

It is easy to over-water a zone with the push of a button, or to equate better results with more water. Apart from newly installed lawn and plants, watering all the time is unnecessary. Do professionals maintain your system or garden? Be sure that you understand why the zones have been programmed as they have, before changing any settings. Rain sensors may be functionally problematical and are consequently disconnected, leading to the sight of lawns being irrigated in the rain. Programming the ideal delivery of water may be considered either an art or a science, but more is not always better.

Scale on clethra

The UMass May 28th landscape letter mentions the presence of a species of Lecanium scale observed on clethra. I have seen two infestations in separate Island locations recently. Reduce stress on plants by mulching and supplemental watering. Spray with horticultural oil, following directions. The previous edition mentioned that Catawba rhododendrons are exhibiting sparse bloom this season.