In from the cold

Cold nights are prompting me to bring non-hardy plants indoors. First it was the houseplants summering on a wire shelf unit in the driveway. Then Steve and I brought in bigger pots, the brugmansia (also known as angel’s trumpet) and hibiscus.

Brugmansia burgeoning on the porch

     We wouldn’t be able to do this as easily without our PotLifter, an ingenious apparatus that winds around large pots and allows us to carry them easily by holding handles. Otherwise I’d be trying to wrap my arms around these awkward, heavy pots myself to carry them up the steps and through the house to their winter quarters.

    The reward for this schlepping is blooms now and through the winter. As soon as I brought the Christmas cacti indoors, their buds swelled, and now the plants are covered with flowers. 

Christmas cactus going wild

    Our hisbiscus does the same, responding to its warmer indoor environment with a generous flush of bright red blooms. 

Hibiscus celebrating coming in from the cold

It flowers through the winter, though less profusely, while thinning its leaves, which turn yellow and drop off one by one. The next summer it fills in again, sprouting more leaves to soak up the sun’s rays.

    The reason these plants benefit from time outside is the vast difference in brightness between the indoor and outdoor environments. I found an interesting chart demonstrating this at PsychEducation.org. This web page is about light treatment for depression, but the chart is equally relevant for gardeners. It shows that typical home lighting provides 100 lux, whereas outdoor daylight with a clear sky radiates 10,000 to 20,000 lux. 

     Light shining through windows is not as strong as outdoor light, and brightness drops off sharply with distance from the window. My shelf of houseplants sits on the north side of the house in summer, so the plants don’t get direct sunlight, which could be as bright as 100,000 lux.

    The extra solar energy allows the houseplants to store up lots of sugars they can use to make flowers and leaves through the winter. The brugmansia is our most dramatic example of this process. Brugmansia is a South American tropical shrub with dramatic pendulous trumpet-shaped flowers. Ours makes

coral-colored blooms nine inches long. 

Dramatic brugmansia flowers

They have an enchanting scent that’s most noticeable at night. 

     The growing season for this plant is so long that we have to move it indoors before it flowers. Unfortunately it doesn’t rebloom. The show is over for this year.

    In winter I can sometimes nurse the brugmansia along next to a large window. If it’s overcome by whitefly, I chop the stem off at the base and banish the pot to the basement. In spring the plant sends up new stems. I choose one as a trunk (this is called pruning for a “standard”). I move it outdoors by Memorial Day, and soon the plant is four feet tall again with large oval-shaped leaves. It’s impressive how much this plant can do with a summer’s worth of sunlight.
   

Soil needs plants

As I become more aware of the “underground herd” of soil organisms, I’m changing my perspective on soil, looking at it as a living system that interacts with plant communities. Two recent paradigm-shifting books shed light on this approach. They are The Living Landscape, by Rick Darke and Doug Tallamy, and Planting in a Post-Wild World, by Thomas Rainer and Claudia West.

    To my surprise, I learned from Rainer and West, “When soil is exposed to sunlight, rain and extreme temperature changes, it is damaged,” and its stored carbon is oxidized and released as carbon dioxide. “The longer a soil is exposed, the harder it is to vegetate later.” 

    Like many suburbanites, I’ve had the fond belief that unplanted areas would be fine for indefinite periods if they’re covered with mulch. 

I thought mulch was enough to protect soil.

Apparently this is better than leaving soil bare to the elements, but it’s not the best approach. 

    It seems that roots and plants’ “underground storage organs” (more on this somewhat risqué phrase in a future post) are crucial for building functioning soil. The channels dug by roots open up space for air and water. When roots decompose in fall and winter, their organic material stays behind as humus, storing carbon and nutrients in the soil. That’s good for plants and good for the climate, too.

Dense groundcover is healthier for soil

    Both author duos describe natural landscapes in terms of plant layers. Among the broad landscape types, my yard is closest to a woodland edge. In this kind of landscape there’s a canopy layer formed by trees, a woody understory of lower trees and shrubs, and an herbaceous layer of perennials and grasses, ranging down to the lowest plants that cover the ground. 
  
    This week I moved some bearded iris that were blocking our view of the fish pond and replaced some tired moss phlox (Phlox subulata) with five pots of bearberry (Arctostaphylos uva-ursi). Their spot is one of the most visible in the yard, within clear view of the kitchen windows. 

The fish pond in August

The bearberry plants join the groundcover layer, and I hope they’ll stay low and neat-looking. I had pulled out some moss phlox a few weeks ago and left the soil bare before covering it with bark mulch last week.

Bearberry and bare soil. I hope it will fill in next spring.

    Both sets of authors emphasize the benefits of a rich and diverse groundcover layer for providing habitat for insects and other small organisms. Native bearberry should help in this regard. I’ve certainly got lots growing at ground level. Over the years I’ve planted something in just about every inch of garden soil. 

    When I squeezed in those little plants I couldn’t resist bringing home, of course, it was to help the environment. As one of this year’s presidential candidates would say, “Believe me!”  And I’m willing to do even more shopping for the sake of the earth.

Big noise

When I commit murder, my crime will be caused by the scream of leaf blowers. 

I'm going to argue a leaf blower defense

Their piercing whine has escalated again this fall. It messes with my psychic equilibrium. It drives my husband out of bed at 7:00 on Saturday mornings. While almost all landscape contractors and many homeowners in my neighborhood use these infernal machines, the blowers don’t actually add value. What they do add is a lot of negative health effects, both physical and psychological.

    My city is now following a trend toward restricting use of leaf blowers. Last fall the aldermen held hearings on the subject, with landscapers contending that they need the blowers to make a living, while many residents complained they were being tormented by noise generated for others’ profit. The city is considering an ordinance to restrict use of leaf blowers to the periods from March 15 to May 1 and October 15 to December 1. 
 
     This change is too modest for my liking. Why should so many of the best gardening weeks of the year be violated by the noise of leaf blowers? I’d like to know I can enjoy peace and quiet when I step out my back door. Many people testified to lost time for work, conversation, and sleep when the blowers are nearby.

    Other than the obvious effects on quality of life, leaf blowers cause other serious problems. Landscape workers suffer some of the worst of them. 

Hearing protection for operators is often neglected

Sustained exposure to noise at up to 100 decibels, such as that generated by the blowers, can cause permanent hearing loss, raise blood pressure, and lead to coronary artery disease. 

     Some people call the machines debris blowers, because they’re used to move anything lying on the ground, not just leaves. In the process they lift dust, animal feces, landscape chemicals, and whatever else is on the ground into the air, where vulnerable people—especially children and elders—breathe them in. The inefficient two-stroke engines of gas leaf blowers also contribute heavily to air pollution. To top it all off, there’s evidence that the high-velocity stream of air actually damages plants.

    It’s not the case that a lush suburban landscape can’t be maintained without leaf blowers. In fact, Beverly Hills and Carmel, California were early adopters of leaf blower bans back in the 1970s. They’ve managed to struggle by.

This Beverly Hills homeowner has managed to cope without leaf blowers

    We don’t have to let marketing and available technology determine our landscape practices. Who says a neat yard is one with no leaves or twigs on the ground? 

 

In my neighborhood, custom demands no leaves on the lawn

Outdoors is not the same as indoors, thank goodness, and a lawn doesn’t have to look like a freshly vacuumed carpet. 

     We’ve been sold a bill of goods on this, and we’re paying for it every time we’re interrupted by the whine of the leaf blowers. If we could accept more natural conditions, where plant debris is allowed to decompose into the soil of garden beds

Decomposing leaves build soil

and—gasp!—even lawns, we’d save ourselves a lot of money and trouble, and we could dispense with obnoxious landscape machines.

Banking on living soil

Have you been hearing recently about your gut’s microbiome? All of a sudden we’re recognizing the importance of microorganisms that live in our intestines for maintaining good digestion and general health.

    Similarly, we’ve recently focused on the importance of living things in soil. Instead of noticing just physical properties—sandy versus clay soil—and chemical aspects—acidity and concentrations of minerals—we’re zooming in on the rich community of organisms that live in and maintain soil. Without them, our plants wouldn’t be able to grow.
 

Plants depend on soil organisms to make water and nutrients available

    Bacteria, algae, fungi, nematodes, and larger animals such as earthworms and insects all help create and maintain healthy soil and build the pore spaces needed to hold water and air. Bob Schindelbeck of Cornell’s Department of Soil and Crop Science recently provided a useful overview of what these soil inhabitants are up to and how to encourage them in Fine Gardening. I loved his characterization of soil organisms as “your ‘underground herd.’” This is a new perspective, thinking of soil inhabitants as animals on our team that are worth fostering.

 

A large member of the herd

    Because the top few inches of the soil are full of active organisms breaking down organic material and digging tunnels, cooperating with plant roots to create a useful architecture, it’s better not to till soil or even turn it with a spade when you don’t have to. Instead, to add organic material you can just layer compost and manure on top of the soil and let the “herd” mix it in. 

An interpretive sign along a nature walk tells it all

   
To help them do their job, it’s good to avoid compacting garden soil by walking on it, which can collapse the pore spaces, especially when the ground is wet. I have to admit that I haven’t put enough paths or stepping stones in my garden, wanting every inch for plants. I’m going to work on that in future.

More paths would keep me from damaging soil structure

    Another living component of soil that I didn’t know about until recently is the “seed bank,” the seeds lying in the soil awaiting the right conditions for germination. Although some will germinate as soon as there's enough moisture, others stay dormant for many years.

Lotus seeds can stay viable in pond soil for 1200 years

When I used to turn my vegetable garden’s soil every spring, I was bringing those stored seeds to the surface.

Goldenrod seeds were waiting in the soil for a good growing opportunity

    I’m still seeing the results of a deposit I made to the seed bank. About ten years ago, I planted tall verbena (Verbena bonariensis), which produces a vast harvest of seeds. A few of them sprout every spring, fewer now that I’ve stopped turning the soil.

Tall verbena seeds last several years in the ground

    Another withdrawal from the seed bank is happening without my intervention. For the past few years I’ve seen heart-leaved aster (Symphotrichum cordifolium) sprouting all around the yard, even more this year. 

Dormant seeds of heart-leaved aster have sprouted around the garden

This is a species that grows in dry, sandy, and compacted soil. It’s out-competing other perennials that are more sensitive to drought and my heavy feet. Bees are foraging among the delicate flowers, so I’m glad this native aster banked its seeds.

Rain at last!

Whoopee! I’ve returned from a vacation in dry and sunny Italy

Ah, Venice . . .

to find that the Boston area had almost an inch of rain while I was away. It’s amazing how different the garden looks with just that much welcome refreshment.

Wet at last

     The lawn has turned green again, and in containers and beds plants are looking peppy, shedding their tired late-summer appearance. It helps that some fall color is starting to show. Fall-blooming flowers are beginning their display. The whole garden scene is a lot more encouraging.

Japanese maple leaves starting to turn red

    How long will this last? Occasional showers are expected into next week as a storm system gradually moves away. We heard predictions of possible showers all summer, though, and most of them either didn’t occur or dropped only light sprinklings that wet the leaves without seeming to moisten the soil. We haven’t seen sustained rain like Saturday’s in a long time.

    Can’t leaves absorb moisture even if sprinklings of rain don’t make it to the ground? Some water can get in through the stomata, pores that open to allow water out of leaves under non-drought conditions. That’s enough to reverse wilting temporarily. I suppose it’s one reason for creating a humid environment around our house plants with misting or pebble trays.

Ornamental grass flower holding water droplets

     But leaves of most plants can’t take in enough moisture to replace water from soil. Come to think of it, some of those house plants originate in the cloud forest, where absorbing water through leaves is a more common adaptation. New England natives need to get their water from the ground.

Even huge leaves of elephant ears can't absorb all the water the plant needs

    Last week’s inch of rain permeates the top twelve inches of soil. My sandy loam takes in water easily, but it also lets water flow through quickly. Sand holds water by capillary action, the way a sponge or a paper towel does. As water drains through sandy soil, soil moisture drops to the wilting point, the proportion at which plant roots can’t extract water they need. We saw that happen over and over again this summer.

Hydrangea at the wilting point

    Soil water retention is one reason that adding organic material such as compost is so important. The chemical properties of organic material enable soil to hold more water for longer because of adsorptive forces that surround soil particles with a film of water molecules. 

    I hope that compost and leaf litter—leaves decomposing in place when I didn’t rake or blow them away—are giving my plants a chance to take advantage of this long-awaited rain. If these soil builders just lie on top of the soil, at least they’re preventing evaporation, holding moisture in the soil for longer than if it were bare. 

Compost to the rescue!

    Incorporated into soil by organisms ranging from fungi and bacteria to nematodes, insects, and earthworms, the organic matter does even better. The organic particles hold water near the surface where roots can drink it in. Cheers, Salud, and L’chaim!