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A shady character, tips for shade gardens


Published: 09/11/2012

by Richard Rix

 'As you can see, the shade here makes it virtually impossible to grow anything,' says my friend Victoria, her bare arm sweeping over the large backyard in north Toronto.

We are standing in a virtual wasteland that was once a green delight. Victoria's compact two-storey house is a little way behind us. She describes it as "Minimalist Georgian" but it is comfortable enough, tastefully painted grey and well cared for.

Sharing the dense shade with us are a few stunted hostas. They look like they'd be happier dead. About our feet, occasional tufts of grass sprout up, the remnant of a once thick lawn extending as far as the euonymus, also in the shade. It's a monstrous thing, now isolated and clearly on its last legs, showing more wood than foliage.

Except for a few weeds, and of course the huge tree trunks, that's about it until the point where the shade ends and the bright light of a hot summer afternoon takes over. Then, beyond a margin of green, a variety of shrubs and flowers puts on a cheerful display right up to the fence at the end of the property, making the wasteland we stand in look even sadder by contrast.

At least it is cool where we are. Above us, the mature maple, oak and birch trees provide a thick canopy. Only the occasional splash of sunlight touches down as the wind rustles the leaves.

'Difficult perhaps but not impossible,' I say. 'Woodland gardens are among the loveliest there are, once you realize that shade is not the biggest challenge you face.'

'What do you mean?' Victoria asks, her brown eyes wider than ever.

'You can grow many rewarding plants in shade, deep shade even, but there are other things to deal with first.'

Victoria looks at me in puzzlement. I bend down and scoop up some soil.

"What do you notice about this?" I ask, letting the soil run through my fingers and blow away in the breeze.

"It's dry?" she says.

'Very dry. That's because the canopy acts as an umbrella, carrying the rain away to the edge so it can fall on the trees' most active roots. Once the trees are in leaf, very little moisture of any kind gets in here, including dew, which is an important source of moisture for plants.

'So I have to put the sprinkler to work?'

'A couple of good soakings a week, I'd say, maybe two hours each time, right the way through the growing season. But even before then, what else do you notice about this soil?'

'Dirt is dirt, isn't it?'

'But not all dirt is created equal. This dirt has done its job of nurturing these trees so they could grow big and strong. Now it is depleted, most of its nutrients gone long ago. I guess you rake it clear of leaves every fall, so there's never a chance for a mulch, right?'

Victoria grimaces and nods.

I tap the ground with my foot. 'What's left here has mostly compacted into a solid mass that few plant roots could penetrate, even if they thought it worth the effort.'

'Is this where I dig in a ton of peat moss to break up the soil and help hold the moisture?' Victoria asks.

'Peat moss will improve the texture of the soil for sure but it contains no nutrients. You're going to have to add compost or manure as well. Bear in mind too that peat moss can cake when dry, so mix in some coarse builder's sand with it. Definitely not sandbox sand, though -- it's too fine and will clump.'

'Isn't there an easier way?'

'You could take a short cut and get a few yards of triple mix delivered. It contains loam, peat and sand. Before you dig in anything try breaking up what's already here to a depth of about a foot. It will help the aeration process. And remember to add a layer of compost each spring.'

Victoria sighs and wipes her forehead with the back of her hand as if she has already started the job. 'So, I improve the soil and provide adequate water, but isn't this shade too dense?'

'Well, what you might do is lop off some of the lower branches of the maple and the oak so that there's at least 10 or 12 feet of headroom. You'll find that the early morning or late evening sun will penetrate for a couple of hours a day, plus extra light will get in from above. Also, as the season wears on, the sun sinks lower in the sky and the rays become more oblique. They'll reach under here quite nicely. The birch isn't a problem since its growth is upright and its shade less dense.'

'Okay. I've improved the soil, added moisture and lessened the shade. What can I actually grow here? I've always wanted a rose garden.'

'Forget the roses,' I say. 'Some plants must have full sun for most of the day, roses among them. But astilbe, hostas, hydrangea, foxglove and monkshood all do well in shade, and for annuals there are impatiens and begonias. Good shrubs include the yews, winterberry and viburnum, and you might try false spirea near the edges. For ground cover, periwinkle is hard to beat.'

'What do you call that first plant again?' Victoria asks.

'Astilbe? It's a graceful old-world plant. It grows a couple of feet tall with fernlike leaves and fine, feathery blooms starting in late spring, usually pink, red or white. There's a nice burgundy version too. You plant them in groups for best effect. Never let them dry out and clip the blooms as they fade, and they'll flower into September.'

'Astilbe,' Victoria repeats. 'Sounds lovely.'

'Any idea where the name comes from?' I ask.

Victoria shakes her head.

'It's a perennial.'

She looks at me vacantly. 'So?'

'So, astilbe there next year.'

Victoria groans all the way out into the sunlight, leaving behind my lame apology and suggestions as to spring bulbs.


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