Norway maple

Rooting

A couple of weeks ago, I engaged in yet another epic struggle with tree roots.

A perennial bed that was root-free when first planted (about twelve years ago) had been showing signs of decline for several years. Plants were smaller and obviously struggling, especially the hostas. Turns out hostas don’t compete well in rooty situations; strange, considering at least some species are native to woodlands. Not woodlands of Norway maples, I suppose.

I’m pretty philosophical about the older beds in the back garden. After all, they are close to five large trees, three of them maples (1 red, 2 Norway), whose roots interlace in a network throughout that 50 by 50 foot space. Goodbye, vegetable patch. Tough plants only. But this newer bed, situated in a narrow strip of land between my house and my neighbours’, was, I thought, far enough from any tree to remain root-free. The drip-line (canopy edge) of the closest maple was safely distant, and tree roots don’t extend beyond the drip-line. Or do they?

Yes, they do. Roots roam far and wide, as it turns out. Once I discovered creeping rootiness in that new bed, I started reading up on how tree roots grow. There was surprisingly little written for home gardeners, even those who are familiar with Latin plant names. I found a lot of scientific papers written by researchers in the fields of forestry or agriculture. Their focus was narrow and their terminology over my head.

Finally, I found this — relatively comprehensible and relevant to my situation. Also discouraging. The drip-line idea is one of the fallacies. Au contraire, “it is not uncommon to find trees with root systems having an area with a diameter one, two or more times the height of the tree.”

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This isn’t how it works! (Image from Pixabay)

Trees send out long, questing roots that keep on growing as long as there’s a reward in the form of water or nutrients, as in a fed and watered perennial bed. The roots run along horizontally, sending up vertical subsidiary roots ending in fine mats of feeding roots. Those are the ones that make that typical ripping sound when a spade is thrust into the soil.

So I tried a strategic strike. I dug up a clump of purple monkshoods (Aconitum napellus) and a few young hellebores at the end of the bed closest to the tree I suspected to be responsible for the root. Then I excavated down two feet and indeed found not one, not two, but three roots a couple of inches apart, each of them about two inches in diameter. Using a nifty little saw (actually intended for cutting wallboard) and a hatchet, I removed sections of these roots, one to three feet in length. Then I dumped in some compost and replanted the aconites and other plants. Thanks to cool and rainy weather, they recovered nicely.
I hope this will give the perennials in the beleaguered bed a chance, if only for a season or two. I don’t relish the thought of a full-bore rebuilding of the entire bed in the grand manner. This rather limited effort was enough for an aging gardener.
October 20, 2011

Hostas, autumn of 2012.

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Rain Envy

When I hear about devastating floods, as in Louisiana just now, I wish rain could be better distributed around the continent. Especially now, when I have just spent an hour raking leaves. Not yellow and orange autumn leaves, but dead, dry green leaves jettisoned by the Norway maples, along with zillions of maple seeds, as the trees respond to what has become a hot, dry summer.

Norway maple seeds and withered leaf.

Norway maple seeds and withered leaf.

In April and May we had at least three hot spells, with temperatures freakishly above normal for several days. June and July were relatively cool, with just enough rain to stave off a drought, but the last six weeks have been totally dry. I delayed starting my usual summer watering program well into July, hoping to encourage plants to toughen up and send their roots well into the ground. That’s the advice of seasoned gardeners such Beth Chatto, author of The Dry Garden. She claimed never to water once plants were established, but I can’t make myself do that. At first, I limit watering sessions with sprinklers to two hours every two weeks for each area of the garden (noting dates so I can keep the schedule straight). Eventually, though, it becomes clear that this isn’t enough. Either I have to start watering at least weekly or give up and let the plants struggle on as best they can. By late August, most have made as much growth as they’re likely to, and most have finished blooming, so they really don’t need as much water as they do earlier in the season. (That’s what I tell myself, anyway). But parts of the garden look really bad right now. I’m not going to post pictures — too depressing.

One of the joys of gardening is to see the plants one has chosen doing well, growing to their maximum sizes and blooming when they’re supposed to. Participating in the cycle of sprouting, growth, budding, blooming, withering and dormancy is what it’s all about. But a drought short-circuits the process and leads to oddball scenarios like raking up bushels of dry green leaves under a hot summer sun. And instead of a graceful transition into fall colours, I’m seeing an abrupt case of the browns.

The weather forecast for the next week includes three days with high temperatures between 27 and 30 degrees C (81 to 86 F). After that it will cool down to 21 (about 70 F) but there is no rain in sight.

On the plus side, tomatoes are ripening on the vine, and in the front garden (less beleaguered by Norway maple roots), asters are showing a million buds, some of which are starting to open. That’s where I go to reassure myself that some things are working out as they should.

Aster "Pink Cloud" starting to bloom, with lots of buds waiting to open.

Aster “Pink Cloud” starting to bloom, with lots of buds waiting to open.

 

Purple aster, pink nerines and ornamental grass "Little Bunny"

Purple aster, pink nerines and ornamental grass “Little Bunny”

Radical Ruminations

Poised on the brink of another spring — and retirement! — I’m considering the options for renovating my garden. As I’ve lamented in a number of posts, the back garden is dominated by two mature Norway maples and a Tree of Heaven (Ailanthus). The entire space (about 30 x 50 feet) has been infiltrated with a solid mat of maple roots, which makes it difficult to grow any but the toughest plants, especially in soil that is mostly sand, and in a summer-dry climate.

 

The Norway maples. Imagine the roots!

The Norway maples. Imagine the roots!

 

The Tree of Heaven. The huge red maple on the right is on a neighbour's property.

The Tree of Heaven. The huge red maple on the right is on a neighbour’s property.

More than once, I have decided to have the trees removed — all three of them. That would open up the sky above the garden and get rid of the roots (eventually). I could grow plants well that barely perform now — peonies, roses, delphiniums, irises! The water lilies in the pond would actually bloom!

Then I think about the disruption. A vigorous climbing rose (white flowers with a pink tinge, very double, in May and June) has slung itself over the lowest limbs of one of the maples. It would have either to be cut down or provided with some other support. Men with size 12 feet would tromp all over the place and there would be all that wood to deal with.

Climbing rose in maple

Climbing rose in maple

Then there’s the expense. Tree removal is not cheap, and I am about to swap money for time.

So I come around to leaving the trees alone and working on the plantings that share space with them. Here, I have a few options:

  1. Remake the Beds. This means digging up the plants I value and stashing them somewhere while I dig out the surface roots and amend the soil with compost and other goodies. Then replant, adding new plants suitable for dry shade. Advantage: the plants will grow quite well for a while. Disadvantages: Back-breaking labour, and the effect would be temporary; in a few years the tree roots will re-grow.
  2. Adjust the Beds. Identify attractive (to me) plants that actually thrive under the present conditions. Get rid of all the sad sacks and weedy specimens and add more of these superstars — mainly hellebores and ferns with spring-blooming bulbs. Fussier things (delphiniums and lilies) could be grown in pots and parachuted in for blobs of colour in season.
  3. Keep the Status Quo. The trouble is, in gardens, there’s no such thing as status quo. Succession kicks in, some plants die, others prosper and in a few years it’s all rose campion, purple toadflax and feverfew jostling around the original hellebores. And yet, even a mess like that can look amazingly good in the slanting light of a summer evening, as long as the bed is defined by edging and trimming.

In the short term, i.e., the next year or two, I think I’ll go with a combination of options 1 and 2. The first thing will be to make the 18-inch tall wooden dog fence along the front of this area taller (by adding 3-foot pickets at 8 to 10-inch intervals) and installing a gate between the two sections of fence. That will make it possible to remove the goofy wire fence around the edge of the circular lawn. Aesthetics apart, that fence makes working in those beds way too hard.

Dog fences.

Dog fences.

The next step will be to identify the plants that do well here already, both “quality” and “weedy” types. Undesirables and struggling specimens will be removed and selected areas dug over and replanted. (Of course all these labours will be performed by me, but somehow I can’t quite bring myself to say “I will remove, dig, replant, etc.”)

I keep reminding myself I will have ten extra hours most days of the week in which to accomplish this stuff. One way or another, the place will look like this again. Or better.

The Back Garden, May 2010

The Ex-Veg Patch

I used to have a vegetable garden. It occupied a space of about 15 by 25 feet across the path from two perennial beds. It was (and for that matter, still is) laid out in a pattern of diagonally bisected squares I had copied after reading an article about Rosemary Verey’s garden in England. (By the way, the triangular beds that result from this are the devil to dig and plant).

There is an apple tree (Yellow Transparent) almost but not quite in the centre of the back part of the patch. It’s surrounded by different kinds of mint, with a solitary clump of fennel to one side.  A triangle in the middle of the layout is occupied by plants of lavender, hyssop and thyme. Others host rue, oregano, echinacea and more mint, while one triangle is given over to a couple of rhubarb plants. Vegetables (tomatoes, spinach, chard, lettuce and peas) used to grow in the space that remained.

After a few years, I noticed that the tomato plants were smaller every year, and less productive. The soil was always dry. The obvious reason was the two Norway maples 20 feet to the west of the veg patch, and the Ailanthus (“Tree of Heaven”) to the north. These tough, pushy trees were sending roots into the patch and hogging the water and nutrients.

The obvious cure for this unhappy situation was removal of one or all of the trees. Tree removal, however, is costly and disruptive. The trees are still there and the vegetable patch is now the ex-vegetable patch. Self-sown quasi-weeds (campion, toadflax, echinops and mulleins) have moved in, along with plants I’ve moved there for lack of better places, such as spare echinaceas and a big mauve dahlia whose old spot had become inhospitable. I’ve also parked some potted delphiniums and lilies near the feeble (but intensely fragrant) rose “Fragrant Cloud,” which also lives in a pot.

Right now, despite the drought and possibly because of the hot summer, the ex-veg patch looks pretty good.

Potted Delphinium and potted "Stargazer" lily

Potted Delphinium and potted “Stargazer” lily

Transplanted mauve Dahlia and self-sown Echinops.

Transplanted mauve Dahlia and self-sown Echinops.

Second set of blooms on rose "Fragrant Cloud" and new growth on potted Delphinium.

Second set of blooms on rose “Fragrant Cloud” and new growth on potted Delphinium.

The Ex-Vegetable Patch today

The Ex-Vegetable Patch today

What about vegetables, you ask? Well, there are four potted tomatoes, along with all the other stuff. (Of course, tomatoes are technically fruits, but that’s OK).

 

Dry Shade Revisited

Since I started this blog, nearly two years ago, by far the most popular posts have been the two on tough plants for dry shade, especially in spring when people start planning their garden activities for the coming season. It seems that there are many gardeners struggling with dry shade, trying to find plants that tolerate dry shade conditions and look good.

I’ll bet this is a common scenario: someone buys a house and lot and decides to make a garden. But the lot harbours at least one, and possibly several, large trees. Even if the effort of digging up the rooty soil under the trees to make planting beds doesn’t discourage the prospective gardener, the eventual failure of most of what is planted will do the trick. Unless the gardener is willing and able to do tree removal, that may be the end of their garden.

Or it may be a more insidious situation, like my own. When I began gardening here in 1992, the two large Norway maples on the western edge of my lot had been lopped by the previous owner of the place. Ugly though this treatment was, it meant that the back yard got a fair amount of sunlight. The first year or two, I was able to grow cucumbers and even corn in my minute vegetable patch, not to mention tomatoes and pole beans.

Ten years later, the maples had regrown and moreover had sent out a mat of roots into the vegetable patch (not to mention the perennial beds that are closer to their trunks). Shade was way more prevalent. Cucumbers? Forget it. (I gave up on corn once I realized how many raccoons lived in the area). The tomatoes did less well every year, until by 2009 I had resorted to growing them in big pots parked in whatever sunny spots remained.

In the perennial beds, it soon became clear which plants could tolerate shade and root competition and which could not. Delphiniums and lilies, even the tough Asiatics, dwindled away over several years. Blue poppies gave up immediately when roots re-invaded their carefully prepared bed. This spring, things don’t look good for a tree peony that did relatively well for years. About the time I gave up on tomatoes in the vegetable patch it started to weaken and may now be in its final gasps.

Shade is a problem for sure, but it’s more than that. There’s also the matter of what’s happening underground. Roots, in other words. Most of a tree’s feeding roots are in the topmost one or two feet of soil, right there with the roots of herbaceous perennials and small shrubs. They compete with the smaller plants for water and nutrients, but they may also do something else — a phenomenon known as allelopathy, which is a process by which a plant produces biochemicals which affect the growth of nearby plants. Norway maples are suspected of negative allelopathy, especially in places where they are an introduced species. So is the Tree of Heaven, under which I planted my doomed blue poppies in the fall of 2000. They bloomed beautifully the following spring, but died soon after.

There is almost no mention of allelopathy in most gardening books, even those that have sections on shade gardening. From my rather superficial internet research on the topic, I see that much of what has been written is academic papers in forestry and agriculture, or to do with the interactions between introduced trees and native understory plants. A few bloggers have written about it as well, for example, this post by Curtis Adams. There is definitely scope for investigation of this subject as it pertains to ornamental gardening.

When I first discovered allelopathy, I had an Aha! moment. Yes, those tree roots are indeed evil, poisoning my delphiniums as well as bullying them. But in the end it comes down to this — either I get the maples cut down, or stop gardening under them, or do as well as I can with conditions as they are. Which I’ve known for years.

Another option, of course, is to move. Drastic, perhaps, but if I ever purchase another patch of land with the intention of gardening upon it, that patch will be tree-free. In the meantime, this year’s massacre of maple seedlings has begun.

Happy Plants in Dry Shade