Roof residents, or where green is not necessarily good

Written January 21, 2013, published in late January, 2013, all photos by Kathleen Sayce

Several species arrive quickly on suitable roofs, starting with algae and bacteria. Algae are tiny plants that are so small and light that their spores blow through the air. These come in several colors, including green, red, orange and golden brown, and also live on trees. Black stains on asphalt shingle roofs are usually photosynthetic bacteria, as are olive brown globs and bubbles that can make the roof appear to be buried in gelatinous slime. 

Two species of moss share space on an asphalt roof with a brown-black cyanobacteria, Nostoc commune. The mosses are seen year round; this bacteria appears in late fall on suitable roofs. 

Lichens and mosses soon follow, and are also tree inhabitants. Lichens may be inconspicuous for a couple of years before they are big enough to form more than a thin gray or black film, but mosses go from thin green films to tidy clumps in one year.  The moment mosses form moisture-holding tufts of green, gray, gold and silver, worms and other invertebrates arrive to live under them. Have you ever seen a crow walking a gutter or a roof, turning over moss clumps? That crow is hunting for juicy protein-rich worms. Tiny beetles, other insects, springtails, millipedes, tardigrades, isopods and other tiny animals also live in the mosses, and yes, these species also live on trees. 

Two mosses grow together on a roof. One is starting to produce spores (the red stalks will grow spores in a few weeks); this is a cosmopolitan moss, Ceratodon purpureum. 

Roof occupancy does not stop at algae, lichens and mosses, and invertebrates. As leaf litter builds, humus forms on roofs and in gutters, and ferns and plants with seeds that float in the air show up.  On well-mossed roofs I’ve seen massive clumps of Licorice Fern (Polypodium glycrrhiza), along with Willowherbs, Cat’s-ear and Dandelion. These plants all have seeds or spores that float on the air, so it’s no surprise that they are easily lofted to a roof. Sitka spruce and red alder have seeds with small wings that blow on the wind, as I realized the year I pulled five spruce seedlings from a gutter full of compost.  In my defense, I’d sprained an ankle the prior summer, and did not climb ladders for more than a year. That was all it took to fill the gutters with conifer needles, for those needles to form compost, and for spruce seeds to arrive and germinate. 

Cyanobacteria, Nostoc commune, forms thick gelatinous masses on roofs among leaf litter and moss patches. 

For heavier seeds, there are birds to carry seeds; they eat the fruits and poop the seeds out high in trees, on favorite perches by bird baths, and on roofs. On a well-thatched roof, thick with natural leaf litter and mosses, grow holly, ivy, blackberry, elderberry, black currant, trailing currant, salmonberry, thimbleberry,  and twinberry, to name just a few local species that often end up on poorly tended roofs. 

This healthy clump of moss had three worms living beneath it when it was turned over. 

Why cleaning is necessary

Mosses have small proto-roots that exude weak acids to eat into bark and help anchor the plant. These same acids eat into and through asphalt and wood shingle roofs, which unlike trees don’t keep growing new surfaces under the bark. The roof dissolution process takes years; eventually, the shingle is riddled with holes. Now, when it rains, the water drains into the building instead of down the roof to the gutters. Wood fungi, termites and carpenter ants take up occupancy in the damp wood under the roof. At that point, your house is toast, unless you replace the roof and rebuild damaged structural elements.  

Birds don’t help, either. Where birds like to congregate, bird poop falls, and this feeds plants. A favorite roof-roost for pigeons, for example, will grow impressive moss and lichen patches down slope from the roost. Bird poop is corrosive, and will help roofing material surfaces to break down quickly. There are many devices to keep birds from settling on roofs:  Rows of ridgetop spikes and spines; rolls of spiky-spiny wire; long flexible wire spines to go between standing seams on metal roofs; bird-scarers, like large plastic owls; and whirly-gigs with bright reflective sections. 

The simplest way to reduce these problems on roofs is to not let them start:  Keep the roof clean; every year or two clean it off.  Don’t forget walls, window frames, decks and steps. These species aren’t fussy; they’ll grow anywhere there’s enough moisture, and too little disturbance. If you want your roof to last, mosses, leaf litter, and their companions have to go. 

Some people clean during the dry season, others during the wet season. My father waited to clean gutters during the first rains each fall. As a child, I thought everyone cleaned gutters in the rain. I prefer midsummer myself, when the roof is dry and the air is warm. Some people put down copper or zinc flashing or spread zinc powder; these metal salts are toxic to mosses, lichens and algae. As metal salts wash down the roof, they kill the plants and fungi. Others wash roofs, and then during the dry season, spray on a layer of detergent. The detergent kills germinating spores and young plants of algae, lichens and mosses. It must be redone every two or three years.  You still have to check gutters, downspouts, and subsurface storm drains, if you have these. 

No matter which method you use, be safe. Set ladders properly on level firm ground. Have a safety spotter on the ground. Don’t work on slippery wet roofs––wait for dry weather. If you must be on a roof when it’s wet, use a safety harness. Wear sturdy boots with gripping soles. Put the cell phone aside until you are back on the ground. Your reward is a roof that may last for most of its planned design life, instead of being replaced decades too soon. 

Broadening Organic: Nutrient Dense Foods

Written January 4, 2013, published in mid January 2013. All photos by Kathleen Sayce.

The debate about organic versus convention food production goes back and forth. One study says organically grown food is healthier. Another says there is no difference in nutritional value between organically- and conventionally-grown foods, except for the level of pesticides. No surprise, organic foods have lower pesticide levels. A third says that soil amendment costs are higher on conventional farms, lower on organic farms. Another says labor costs are higher on organic farms due to more hand weeding. Organic food gardens cost less to operate, because fewer amendments (fertilizers, pesticides) are used, and less water is needed. Conventional food gardens produce more food for lower labor costs, but at higher health risks for farm workers due to pesticide use. 

A refractometer with three kale samples, from left to right, Red Russian, Red Curly and Green Curly Kales. 

Food Quality

What’s a home gardener to conclude from this argument? I say:  Expand your definition of organic gardening and look at food quality, specifically at nutrient density:  What form of gardening produces the most nutrient dense food?  ‘Properly mineralized soil’ is the correct answer. This goes beyond avoiding crunchy, sugary, salty processed foods, as good as these taste, to plant and animal foods with high quantities of minerals, proteins, fats, sugars and secondary compounds. This is nutrient density, which we can measure, and more importantly, we can taste.  

Plants grown on optimally healthy soils have higher levels of dissolved solids and minerals in their intercellular sap than do those grown conventionally or on nutritionally out-of-balance soils, regardless of the management method for that soil. These plants are healthier, and their roots, fruits and leaves and stems, which we eat as foods, are more nutrient dense.  They deliver optimal food quality and flavor to us, the eaters.  Likewise, animals grazed on pastures managed for optimal nutritional health are healthier. 

A light orange carrot with mashed fresh carrot in cheesecloth, ready to measure the carrot's juice in the refractometer.

Nutrient Density

Density is measured as dissolved solids in plant juices using a refractometer, a centuries-old device that uses refraction of light to measure fluid concentrations in Brix units. A bar of color crosses a numerical scale; you read the number on the scale. This is the Brix of that solution.  In measures of plant sap quality, the higher the Brix, the better. 

Wine, cheese and juice makers use refractometers to measure Brix and determine ripeness in grapes, tomatoes, berries, and other fruits, because there is a strong correlation between the level of dissolved solids in intercellular sap, and the sugar levels and flavor of the fruit. They often eat the fruits to compare flavor to Brix units, calibrating their sense of taste to these measurements.  Yes, you can taste the differences. High Brix fruits have more flavor. I use my garlic press to mush fresh veggies, and a bit of cheesecloth to squeeze the juice from the crushed sample to test. 

Studies of food quality rarely include the Brix levels of plant saps. Those few studies that do so show that fruits, grains, seeds, and vegetables grown on healthy soils with optimal nutrient balances have higher Brix levels than do conventionally grown foods on unbalanced soils.  

A green curly kale sample in cheesecloth with bright green fresh juice.

Food Quality, Flavor and Health

As consumers of mass-produced foods, many of us have never tasted these flavor differences, due to lack of exposure to truly nutrient dense food. Bring on the compost, humus and biochar, and soil tests for minerals, so that we can determine exactly which minerals our vegetable gardens need. In a healthy soil with optimal levels of nutrients, all of those plants, including fruit vines and shrubs, peas, carrots, beans and even lettuces, will nosh in style, and deliver more nutrition and flavor.  

The result of eating plants grown with optimal soil nutrition is that we can be healthier. So step aside of the arguments about conventional versus organic, and go beyond, into an expanded definition of organic gardening with nutritionally complete soils, with regular soil tests, appropriate mineral supplements, and grow healthier plants. Get optimal flavor, high mineral levels, and higher levels of sugars, proteins, fats and other flavorful compounds. 

Anyone can do this. Gardening is not difficult; it takes time, and soil tests to determine what amendments your soil needs to optimize nutrition for your home garden, orchards, lawn or pasture. The gain is in taste and health.  Steve Solomon’s latest book, The Intelligent Gardener, discusses soil nutrition for growing optimally healthy foods in sufficient detail to get you started. 

Winter is a great time to be planning next year’s vegetable garden. Order soil tests, then add the right minerals to improve your soil, for great eating next summer. Summer is coming, right? The rain will end sometime, right? 

A red curly kale sample with its red-purple colored fresh juice. The chlorophyll is in there, but masked by the reds and purples of the red kale plant.