If all you have is a hammer, everything looks like a nail

Why are landscape contractors so attached to work they can do with machines? A recent conversation with a fellow gardener reminded me of this frustration. Her lawn service uses a weed wacker—a string trimmer—to cut back weeds in her yard instead of uprooting them. 

A string trimmer shortens weeds but doesn't remove them

As I pictured it, they’re leaving the weed plants a couple of inches tall. From the weeds’ point of view, this is helpful pruning. They marshal their underground resources and send up more growth. She finds the weeds are spreading. The crew leaves her property looking neat, but they’re not serving her gardening purposes.

    I have the same experience, and it’s getting more acute as I shift toward my version of sustainable gardening. I employ a landscape contracting company that I’ve known for years. I know that the leadership of the company includes several people with strong horticultural knowledge. The actual mowing, though, is done by a team of two or three young men with many stops on their schedule for the day and little time for tailoring their approach to suit my wishes.

Can I buy lawn care that's consistent with my sustainable approach?

    Last time they visited, I happened to be out in the garden. The team leader stood next to my new perennial bed, painstakingly mulched with shredded leaves, and asked whether I wanted them to use the leaf blower. He remembered that I’d said no to leaf blowers in the past, for which I’m grateful. But I had a strong feeling that if I hadn’t been at home, my leaf mulch would have been blown off the bed in a few seconds, and I’d have been stuck buying bark mulch from the garden center.

I put that leaf mulch down on purpose

    That would have wiped out all my efforts to mulch with materials I find near home, minimize carbon cost, and maintain habitat for native insects.

    I’ve talked with the supervisor of the team at least annually about how I want to maintain the garden. I’ve put up signs asking the men not to remove fallen leaves from the property. Things have improved, but there are regular relapses. My approach just doesn’t seem to compute for them.

    Another sore spot is grass clippings. It took effort to get across the message that I don’t want them removed from my yard. That’s organic material that should stay here and build soil. I ask to let the clippings lie on the lawn. 

Instead of moving clippings to the compost bin, you can let them compost in place on the lawn-photo anneheathen

Yet each spring I’ve had to call and beg for this request to be honored. It’s not the way the team is used to doing things, and it probably looks messy to them.

    It may be more efficient for landscape contractors to do the same work in every yard and to work with power tools—gas powered mowers, leaf blowers and string trimmers--despite the dust and exhaust the operators inhale and the hearing loss they incur from the noise. But we customers are paying for this one-size-fits-all service. It’s time for us to vote with our pocketbooks and seek out contractors who are equipped to accommodate a more plant-friendly and environmentally conscious approach.

Pushing up through the leaf mulch

 

Planting trees

I recently spent a fun morning planting trees in my neighborhood with the Newton Tree Conservancy.

The NTC is replacing street trees that have died

    The NTC and the city had made all the preparations, leaving us volunteers with the happy task of actually planting the young trees, each with a trunk diameter of about 1 to 2 inches. Our director of urban forestry, Marc Welch, had chosen a mix of species, minimizing the risk that one pest could wipe out all the new trees. Homeowners signing up for street trees in front of their houses had agreed to some conditions: they’d be present on planting day, they’d provide a hose and water access, and they’d be responsible for watering the trees for the next two growing seasons.

    The city team dug a hole where each tree would stand. Beside each hole they left a sapling wrapped in a large plastic bag, to keep it from drying out, a small pile of bark mulch, and a watering bag. You may have seen these cleverly designed green bags around the base of newly planted trees. The bag zips around the trunk and has a double lining, creating a pouch that holds 15 gallons of water. 

A tree watering bag can be filled up with a hose

Tiny perforations at the bottom of the sack allow water to drip out gently over five to seven days, keeping the soil moist.

    Our job as planting volunteers was to make the hole fit the roots of each young tree. Some had spreading roots, others headed deeper into the ground. We were careful not to bury the trunk’s flare, the widening where the trunk meets the roots. That’s because planting too deeply starves the roots of oxygen. 

Central Park. A trunk should flare at the base like this.

 We needed to deepen some holes and replace soil in others. Once the tree was in the hole, a popular way to judge how high it was sitting was to lay the handle of a spade across the hole. We had to make our holes wide enough so that the roots had room to spread out.

    One person held the tree trunk straight, while another gently shoveled soil into the hole. When the soil in the hole looks poor, it’s tempting to enrich the backfill with compost or other amendments. Research shows that it’s better for the tree if you don’t. If the roots find enriched soil in the hole, they’ll stay there and not grow out into the surrounding soil. We returned the original soil to the hole without embellishment.

    We mulched around the trunk of the new tree, being careful to leave a space around the trunk and form the mulch into a saucer, not a dome. Over-mulching prevents needed air and water from reaching the roots.

 

Far too much mulch. Four inches is the maximum safe depth.

Then my planting partner Hal showed me how to set up the watering bag and fill it with water. 

     The weight of the water tended to tilt the trunk at first. Walking by the trees this week, I see that with the watering bags less full, the trees are upright. It’s great to see the young trees settling in.

Felix checks out one of the trees we planted

   
   

Wake up and smell the leaf mulch

Last fall I changed a longstanding fall garden clean-up routine: I didn’t rake fallen leaves from the garden beds and chop them up in the leaf shredder. I didn’t mulch those same beds with the chopped leaves. I didn’t cut the dead perennials’ foliage and flower stalks to the ground. I just let the tree leaves lie on top of the plants and left the dead stalks standing.

Meadow rue (Thalictrum aquilegiifolium) emerging through the leaf litter

    My reason for this change of approach was that I’d learned that native insects shelter and lay eggs under fallen leaves, in crowns of dormant perennials, and in those dead flower stalks. If I left those insects alone through the winter, they’d have a better chance of surviving, reproducing, and contributing to the garden ecosystem in spring. It was hard to hold myself back from cleaning up at the end of the garden season. I have to admit it was also a lot less work.

Beneficial lacewing finding winter cover

    Through the winter, I watched those ragged stalks and those whole leaves, especially on the new perennial bed that’s right next to the back deck. The leaves are mostly red oak, with some Norway maple mixed in. The garden’s usual winter look, bare but neatly tended, had morphed into either a sloppy mess or a more natural scene, depending how I felt on a given day. 

The backyard scene in March

Now is the time to assess how this lazy approach to preparing for winter worked out.

    I waited impatiently for daytime temperatures to stay in the fifties, indicating that the time had come for lifting the leaves off the new plants and moving them to the compost pile. I was anxious to know how the plants were doing under there. For the past two weeks I’ve been gradually uncovering the deck bed. 

Perennials and a dwarf juniper under the leaves

Dry leaves formed the top layer, but beneath these I uncovered wet, matted leaves plastered to the ground. I chose overcast days with rain in the forecast, not hard to find recently, for exposing the covered plants to the light. Their new foliage was pale from growing in the dark. I didn’t want them to get sunburned from sudden exposure to full sun.

    With the whole bed uncovered, I see that most of the new perennials made it through the winter. Of course, they benefited from other factors besides the leaf cover. Snow covered the bed during much of the winter, protecting the new plants from desiccation and temperature extremes, and there’s been plenty of rain this spring.

    To mulch the uncovered bed, I shredded leaves that I’d stored in the garage in paper yard waste bags. 

Shredding makes mulch that doesn't mat or blow around like the whole leaves

If insects took refuge in the bags last fall, they should have moved out by now. Birds are very active in the yard, which seems like an indication that they’re finding insects to eat. 

A cardinal couple is building a nest

     I’m hoping that more native insects will enrich the garden’s food web this year. Not only animals will benefit. I’m aiming for plant-friendly balanced populations of pollinators, leaf-eaters, and the beneficial insect predators that will keep leaf-eaters under control.

Leaf litter and native insects make congenial conditions for woodland plants

 

Flowers at last!

Isn’t it great to see flowers blooming and leaves starting to show? 

April forsythia, essence of yellow

In my neighborhood, it’s graceful magnolias, heart-lifting yellow masses of forsythia, and flowering cherries, some romantically asymmetrical like inhabitants of Japanese scroll paintings. 

Magnolias, briefly celestial

    In my front yard the groundcover (Vinca minor) is sporting periwinkle blue flowers among the truer blue of glory-of-the snow (Chionodoxa luciliae). 

Vinca puts on its spring show

The first daffodils and hyacinths have opened. Despite my protests that spring came late, this is all happening exactly on schedule. In my yard, the last week of April is the official start of the outdoor garden season. 

Daffodils among the vinca

    I’ve been struck this year by the beauty of the first tree flowers, not just the ornamental trees with big flowers like those magnolias. Red maple buds (Acer rubrum) have opened to reveal batches of tiny deep red flowers along the twigs. 

Red maple in bloom

This tree has male and female flowers, sometimes on the same tree. By the time the leaves start to open, the fertilized female flowers will already be ready to strew their whirly seed pods, called samaras, on May sidewalks.

Red maple seeds pods

A fascinating study by local biologist Richard Primack elucidated the somewhat fluid gender distribution among 79 red maples in a nearby park. He found that while 75 percent of the trees were male and 23 percent were female, 2 percent varied from male to female from year to year. Of the 77 consistently male or female trees, 12 showed a few flowers of the opposite sex some years. So apparently maples refuse to be defined by the gender binary.

    As much as I curse the ever-so-fecund Norway maple (Acer platanoides) and wish it had never been chosen as a street tree, I find its lacy flowers beautiful, especially seen against streetlights on warm spring evenings. 

Even Norway maples have intriguing flowers

Later we’ll see the dangling flowers of the oaks as these trees prepare to leaf out, last among our local deciduous trees.

A red oak twig

    I’ve been focusing a lot recently on flowers that need insect pollinators, because those insects are essential at the base of the food web for all us animals on earth. Maples, oaks, and lots of other trees don’t have to attract pollinators. They can rely on the wind for pollination, although their pollen can be an important early food for insects such as bees when little else is blooming. 

     That’s why these trees don’t have to make showy, colorful flowers with insect-attracting tricks such as ultraviolet runway markings pointing the way to the “nectar reward.” They just hang out their stamens in open air so that the wind will catch the pollen. That’s also why they make so much of that pollen, as seasonal allergy sufferers are well aware.

     I find that as time go by, I’m more drawn to the subtle flowers of these trees and less to dinnerplate dahlias and their like. Small can be elegant.

Live and learn

This year more than usual is riding on my plant propagation. As part of an ongoing quest to publicize my book, The Sustainable-Enough Garden, I'm planning to participate in our local farmer's market, selling gift baskets for gardeners that contain six-packs of herbs and edible flowers, along with the book and other fun items. I'm starting more seeds indoors than usual, and I'm worrying about them more. If I can't produce the seedlings, then what?

Purple and green basil--will they be ready for market?

    I’m learning first hand that production growing is fraught with many pitfalls. What’s enough water, and what’s too much? Exactly when should I plant each variety to have little plants the right size by June 30, the first market date, and through the summer?

Tarragon cuttings are doing well (left), but only one of 24 seeds I planted germinated (right). Why?

Transitioning the seedlings outdoors to “harden off” will be an anxious experience with many questions regarding correct timing. This growing is like mothering, with all its uncertainty and need for constant vigilance.

    This week I came back from eight days on vacation away from my seedlings fearing heavy attrition. Would they have wilted and died without watering? I’d moved all the seedlings to the basement, figuring they’d need less water in a cool space where evaporation would be slower. 

     I followed the advice of one of my gardening heroines, Thalassa Cruso, for getting houseplants through times when no one’s at home to water. She recommends covering them with plastic sheeting to minimize evaporation. I adapted this for my seedlings by using some rigid clear plastic covers sized to fit over the seed trays. 

A clear plastic cover made for the seed tray is convenient

When I ran out of those, I cut open old dry-cleaning bags to drape over the little plants.

A repurposed clear plastic bag works too

    In the bottom of each tray, under the six-packs that hold the seedlings, I’d already placed a layer of capillary matting, absorbent synthetic fabric that gradually releases water to the pots.  I made sure to water the growing medium and soak the capillary matting before I left town.

Spongy fabric absorbs water and releases it gradually

    As soon as I got home, I pulled off the plastic to check on the little plants. Most of them were fine. I was surprised to find that the growing medium was still moist in many of the six-packs, and much of the matting was still wet. Moss or algae was growing on the surface of the growing mix in some of the pots. That showed how humid it had stayed inside the plastic enclosure, but it didn't seem to be doing any harm.  

    I’d managed to kill some cuttings I’d taken from a rosemary plant I brought indoors last fall. I’d left these uncovered because I thought they’d rot under the plastic, and I hadn’t set their six-pack on wet matting either. Unsurprisingly in retrospect, four of the six dried up, dropped their leaves and died.

News flash! Plants need water to survive

    Lots of questions remain. Clearly farming requires expertise and experience that I don’t have. Even if my farmer’s market project fails, I’m bound to learn a lot this year.

It's spring! Cornelian cherry (Cornus mas) blooming at last

Sex, drugs, and plant propagation

Which is better, sexual or asexual reproduction? It depends who’s doing the reproducing. This spring I’m making new plants both ways. Seeds are produced through sexual reproduction. Each seed has two parents with different genetic make-ups. That means each seed, and the plant it grows into, is a unique individual, like us. I’m growing a lot of my new plants from seed, including vegetables, herbs, and annual flowers.

Each borage and basil seedling is a genetically unique

    Asexual reproduction accounts for a lot of the perennials, trees and shrubs we buy. If you’re a breeder who wants to make sure your dogwood or azalea is exactly like its parent, you clone it. Unlike human tissues (so far), plant tissues have the ability to reproduce whole plants from parts of the parent plant.

A desirable rhododendron can be cloned infinitely

     Right now I’m growing cuttings from last year’s rosemary, bearberry (Arctostaphylos uva-ursi), and coleus. I’m hoping to do the same with tarragon and oregano I bought at the garden center. If these cuttings take root and grow, the plants they grow into will be genetically identical to the parent plant.

Cuttings from bearberry and coleus are clones

I’ve read that some named shrub varieties consist entirely of clones from one desirable plant. Many plants, but identical genes.

    People concerned about biodiversity have a problem with this system. In addition to encouraging us to grow native plants, they want us to foster genetic diversity among plant species. The reason is that a broader gene pool allows a species to adapt to changing environmental conditions. Some individuals in the population will develop greater resistance to heat, drought, flooding, and other challenges. As climate change speeds up changes plants face, they need to be ready to evolve in response.

    There’s an inherent tension between promoting biodiversity and maintaining desirable varieties. If you’re trying to grow a particular tomato, say ‘Brandywine,’ which is open pollinated (not a hybrid), you don’t want your ‘Brandywine’ plants fertilized by pollen from other tomato varieties. 

Tomato growers want to keep varieties distinct

     But if you’re just growing a patch of perennials, say native purple coneflowers (Echinacea purpurea), there’s no reason not to let them mix with nearby members of their species and create a genetically mixed population. In fact, your stand of coneflowers will be more likely to survive if it includes members with different genes that can tolerate varying conditions.

A genetically diverse coneflower population is adaptable

    Except for letting willing self-seeders do their thing, I haven’t propagated perennials from seed. When I want more, I may divide the plants or, as with rosemary, bearberry, and ivy, grow more from cuttings. If a snippet from the growing end of a plant is willing to send down roots, why not make more that way? Divisions and cuttings make clones, just as tissue cultures made by breeders from a few cells grow into clones of a newly-developed perennial. In future I want to learn to grow native perennials from seed so I can help maintain their genetic diversity.

Felix, a new garden helper visiting from New York

I’m off on a trip to the Southeast, hoping to experience spring flowers there and again at home when I return. See you in two weeks.

Fiat lux

With my old fluorescent grow lights getting dimmer month by month, I decided it was time to upgrade the lights I use for fostering my seedlings in the basement.

The more light they get, the stronger seedlings will be when it's time to move outside

    Although we may like the idea of starting seeds on a sunny windowsill, the sunlight that comes through a window isn’t really bright enough to grow strong seedlings. Even if I had an unobstructed south-facing window, which I don’t, plants couldn’t get more than 6,000 lux through the glass. In comparison, outdoor light can reach 120,000 lux in full sun.

Light through the window isn't strong

     As plants stand farther back from the window, available light drops off quickly to only 3,000 lux at one foot. Screens filter out light too, and short winter days reduce light exposure.

    Artificial light does more for seedlings that are destined to grow outdoors. My young plants will need 20,000 to 25,000 lux to grow robustly.

Shorter and chunkier is better

    For years I’ve used fluorescent lights for my seedlings. My first set-up was a cheap fluorescent shop light hung from a board held up by bricks. It did the job. Later I bought a four-shelf unit with two fluorescent tubes at each level. The lamps could be moved up and down, which was convenient for keeping them no more than six inches above the leaves—again, light levels drop off sharply with distance from the source. The bulbs didn’t generate heat; even leaves touching them came to no harm. I could use regular fluorescent tubes for these lamps or choose tubes that offer a color spectrum favored by growing plants.

    Over the years, I’ve had trouble maintaining these fluorescent fixtures. Replacing the bulbs and the starters that are needed for fluorescents turned out to be tricky. This winter I was down to one and a half working lamps.

    Meanwhile, for upstairs I upgraded to a T5 fluorescent, twice as intense as the T12s in those basement lights. I can appreciate the difference. The light looks brighter, and seedlings stay huskier under it.

T5 fluorescent under a windowsill

    Marijuana growers may opt for the even greater intensity of HID (high intensity discharge) bulbs, metal halide or high pressure sodium. This is the very bright light you’ll see in clandestine windowless growing areas in TV crime dramas. My friend Prudence urges me to try growing marijuana, but I’m not up to that level of indoor production yet. HIDs generate a lot of heat, which means you can’t let leaves get as close to them. 

    The next wave in grow lights is LEDs. The Gardeners Supply catalog offers LED light stands for around $250 to $300 per shelf. That’s more than I wanted to spend. Instead, I bought a heavy duty wire shelving unit and four LED shop lights—total cost $280. 

New LEDs. I hung some lamps at an angle to keep them closer to the foliage.

It was easy to hang the lamps from the shelves with the hardware provided. They certainly provide more light than the fluorescents, and they should last for my lifetime. Will their light spectrum work for my seedlings? Stay tuned.