Beware of Greeks bearing gifts

One of my biggest gardening mistakes was planting smooth Solomon’s seal (Polygonatum biflorum). This seemingly modest woodland plant aims for world domination. Now I’m trying to beat back its onslaught.

Smooth Solomon's seal emerges in spring

    I first encountered smooth Solomon's seal in the shade plant section of my favorite garden center. At the time I was coming to grips with the fact that I was gardening in shade. I was delighted to discover lots of plants with pretty foliage in a shady corner at the far side of the sales area. Smooth Solomon’s seal caught my eye because of its arching stems, shiny leaves, and pendant cream-colored flowers. 

Seemed like an understated, elegant woodland plant--photo Peter Gorman

I didn’t seek out native plants at that time, but since it was a North American native, that must mean it wouldn’t run wild, right?

    For several years I thought I’d picked an excellent plant for shady areas where nothing else wanted to grow. About ten years in, though, I noticed that smooth Solomon’s seal was showing up in every shady part of the yard—and that’s most of my garden. Its little blue fruits must have been making their way to new territory. In retrospect, I might have been safer with an attractive Eurasian cousin, fragrant Solomon's seal (Polygonatum odoratum ‘Variegatum’), which has a pretty chartreuse border around its leaves and seems to be less spreading—so far.

A more sedate Solomon's seal? Or crouching to spring

    It’s not too hard to dig out smooth Solomon’s seal. When you do, one reason for its success in dry soil becomes obvious. It has big fleshy rhizomes, underground storage organs that look capable of storing plenty of water and nutrients. 

Rhizomes store supplies for hard times

I’ve learned not to throw these or the blue fruits on the compost pile, because both produce new plants. Moving compost around, I may have unknowingly carried them to new areas of the yard. 

Fertile fruits of smooth Solomon's seal

Instead I now send them out as yard waste, to be cooked at weed-killing high temperatures at the municipal composting site.

    There’s a crabapple tree that I look at every day from our kitchen windows. I’d sure like to grow other shady woodland flowers under it, not just smooth Solomon’s seal. 

A pot of elephant ears attempts to disguise rampant smooth Solomon's seal under the crabapple

What holds me back from ripping it all out is the fear that I’ll kill the tree in the process. I once read a sad story about a man who killed a beloved dogwood by digging among its roots to surround it with daffodil bulbs, and I think I executed a venerable Japanese andromeda (Pieris japonica) when I pounded plastic edging through its root zone.

     So I’m removing the unwanted smooth Solomon’s seal cautiously, bit by bit. Last spring I dug out a wedge-shaped patch of it from the tree trunk to the drip line. This fall I did the same in a slightly larger wedge, arguing that the tree was ready for this because of our wet summer. Time will tell whether I went too far.

A section cleared of smooth Solomon's seal-- for now

    The main remedy will be to plant something else that can stand up for itself in place of the plants I tore out. Smooth Solomon’s seal abhors a vacuum.

Attention friends: I'll be speaking at the Massachusetts Horticultural Society's Ecological Gardening Symposium on November 8 at Elm Bank in Wellesley, MA. Here's a link to the program information. I'd love to see you there.

The root of the matter

Walking my dog at a beautiful park along a stretch of the Charles River, I’ve been alarmed to see heavy construction machines demolishing a small playground surrounded by giant mature oaks and pines. My worry is that digging so near the trees to remove the footings of the play structures, the excavators will destroy enough roots to kill the trees.

    Remember that old diagram of a tree sending roots underground as deep as the tree’s height?

   That turns out to be completely wrong. Roots stay near the soil surface, the majority in the top 1 to 2 feet of soil. That’s because they need the oxygen that’s there for respiration. 

The exposed roots of this tree form a shallow disc, not a deep wedge

    You can kill a tree or shrub if you dig too much in its root zone, even superficially. I once assassinated a lovely mature Japanese andromeda (Pieris japonica) by carving a narrow trench all the way around it for plastic edging that I fondly imagined would keep the sweet woodruff (Galium odoratum) I’d planted as groundcover from spreading (it did nothing of the kind).
    That gave me a healthy respect for how far feeder roots extend from the base of a shrub or tree. I’d thought the roots stayed approximately inside the drip line, the outer circumference of the plant’s branch tips. In reality, when unencumbered, roots extend to two to three times the width of the tree. 

    Not that you can never dig a hole near a tree, of course. You just have to think about how much of the root mass you’re going to interfere with. Since the roots radiate out from the base of the tree, the closer you dig to the trunk, the greater percentage of roots you’re going to kill. If a tree loses 40 percent or more of its roots, it will die. 
    So now I don’t like to see a power shovel digging close to the trunk of a tree. Sure, it saves a lot of time and manpower, but the potential environmental cost is too high. 
     It doesn’t help, either, that a heavy dump truck has been parked next to trees at the site I visited. This will compact the soil and reduce air spaces needed to allow roots to take up oxygen, water and nutrients. There’s more sobering information about tree damage caused by construction at the Minnesota Department of Natural Resources website.

 
    The white pines (Pinus strobus) and red oaks (Quercus rubra) along the river must be more than a hundred years old, judging from trunk diameters of almost 4 feet. They shade the playground and the many people who enjoy running, bicycling and strolling along the river bank. They stabilize the soil.

     As native trees, they’re foundational species for communities of plants and animals. They would be a terrible loss, irreplaceable in our lifetime. 

     New playground equipment is a nice idea. I very much hope the trees will survive its installation.
***
For a story of utterly unsustainable gardening, don’t miss this recent post at The Massachusetts Spy

Fruit of the gods-coming soon!

My silk tree has gone to its reward, leaving a space for a new tree. This week I received a little common or Eastern persimmon, Diospyros virginiana. The Latin genus name means “food of the gods”!

 

Ready to plant

 
This native persimmon produces fruits around the size of golf balls. My goal in planting it is to provide wildlife with food and habitat. Maybe there will be a few persimmons for human residents of the yard too.

'Yates' persimmons from a tree like mine. Grown by Hank and Nghi Frehtling in Willianston, MI in 2013

     So yesterday I went out with my shovel to plant the little tree. Over the last few years I’ve collected quite a list of does and don’ts for planting shrubs and trees. First there was the hole. When I started out, I used to think that a deep hole was good, because loose soil under the young plant would make room for its roots. Lots more is known now about tree roots. They spread mostly sideways, not down. Persimmons reportedly send down a tap root to lower depths, but still, most of the feeder root action will be near the surface where the oxygen is. You can set your tree back considerably by planting it too deep. Today’s planting holes are supposed to be wide but no deeper than the root ball. 

     As usual when I dig in my yard, my hole quickly revealed sizable roots. 

This root crossing the hole had to be left alone

Surrounding trees and shrubs were clearly spreading their roots far and wide. I hoped that my relatively small hole, two feet in diameter, would not do enough root damage to harm the new tree’s neighbors.

     The next step was a bold one. I’ve always been hesitant to mess with the root balls of container- grown plants. But recently I read about an experiment demonstrating that transplanted trees actually did better if the roots were cut back. Cringing a bit, I teased out the potting soil around my little tree’s roots and trimmed away some of the longest roots. I made sure to set the now-floppy mass of roots on a pyramid of soil to keep the stem above ground level. 

After the radical treatment

 

Before-fresh from the container

            





  






I restrained myself from “improving” the backfill with fertilizer or compost. That too turns out to be misguided. It’s best for your transplant to be surrounded with the same soil you dug out of the planting hole. I watered generously and surrounded the young tree with some handy wood chips.

     Last I had to decide about the stake that came with the plant.  It was tightly attached to the stem with five plastic ties. I knew that staking trees is over-rated, and young trees actually grow faster and stronger if they’re allowed to sway with the breeze. I decided to keep the stake until the new tree put out some leaves, just to prevent me from trampling it by mistake. I cut off all but the top two plastic ties. 

These ties seem especially tight

I’ll need to be sure to remove the last two soon, because as the stem expands, the unyielding plastic could girdle the trunk, cutting off the flow of nutrients under the bark.

     I read that a persimmon could produce fruit in as little as three years. I can’t wait!

Sun rays for winter days

Have you read Frederick, a picture book by Leo Lionni? Frederick is a mouse poet who doesn’t join in when his mouse compatriots are harvesting seeds in summer to eat during the winter. 

     He tells them, “I gather sun rays for the cold dark winter days.” He stores up impressions of the warm months. The other mice think he’s a slacker, but when the bleak winter comes, they are sustained by his stories as they huddle inside a stone wall.

    I find myself thinking about Frederick at this time of year. I too have wanted to store sun rays to get me through the winter, to buoy my spirits and also to make things grow next spring. 

Paperwhite narcissi bring some stored solar energy indoors in January

     The sun’s rays are embodied in the basic components of my gardening activity. The brown leaves and needles lying on the ground now, the gray trunks and branches of trees and shrubs, all represent the sun’s energy, captured through photosynthesis and stored in plant tissue. 

    In aiming to garden sustainably, I’m trying to keep that stored energy in my yard instead of sending it away. That’s why I ask the lawn service to let clippings lie on the grass to compost in place. It’s why I chop fallen leaves and use them as mulch. Both add organic material to the soil, which means keeping solar energy here where plants and animals can use it. As one of the resident animals, I want that energy to go toward growing garden plants I love.

    It would be even better if I could keep twigs and branches from trees and shrubs in the yard to make compost, mulch, or brush piles to shelter wildlife. So far I haven’t found ways to do that. Oak branches would take decades to decompose unless I chopped them into chips, which I’m not able to do. On a third of an acre lot, I begrudge space for a brush pile.
    
     My “sustainable-enough” approach has been instead to send out woody prunings to the city’s composting operation with the yard waste and use wood chips kindly delivered by a local arborist, Kevin Newman, for mulch.  This exchange means that the mulch doesn’t originate on my land, but it doesn’t incur much carbon cost for travel—the chips are from nearby trees. 
 

     It was nice to learn that trees aren’t totally locked in suspended animation during the winter months. They’re dormant, with slowed metabolism, but they’re poised to take up water when soil temperatures are favorable, between approximately 32 and 41 degrees.

This white pine appreciates snow cover

    A consistent insulating layer of snow can keep the soil in this temperature range. The snow allows evergreens to keep their needles from drying out and enables all trees to send out new roots in early spring by holding a little of the sun’s warmth in the soil.  Sort of like Frederick’s stories.