by Leslie Cox; Tuesday, June 4, 2013

How many of you have at least one tough spot in your garden? I am sure there must be a few who have an area that challenges your aspirations of being the Master Gardener of your domain. I know I do. More than one area, in fact.

Ever since we put in the bed along our narrow rural road back in 2001 and the big changes that began on the front garden in 2004, I have been struggling to find “what works” in my garden. My problem? Six trees in a relatively small area.

 

 

Three of the trees pose the biggest problems for me. Simply put – they are big. Really big. Their roots go everywhere. So let me put one gardening myth to rest. The feeder roots DO NOT end at the outer reaches of the tree’s canopy. And Graham Rice concurs in his book Planting the Dry Shade Garden (Timber Press, Inc. 2011). According to Graham, and it makes sense, tree roots will reach out in their search for whatever fertilizer and moisture they can find.

When it comes to planting underneath big trees with all their roots…man, it can be a hard slog finding plants that are tough enough to cut the mustard and stand up to those trees.

Well, surprise, surprise. Two of my six trees made Graham’s list of tough trees to plant under – Acer campestre (hedge maple) and Aesculus hippocastanum (horse chestnut). John has one on the list, too…his Acer platanoides ‘Crimson King’ (Norway maple).

I also think my Acer saccharinum (silver leaf maple) should have been on Graham’s list. As should any tree that is over 25 feet tall, I don’t care what the species. When it comes to the root system on a large tree, you are talking tough planting.

But through trial and error, plus sheer perseverance, my front garden is now “almost there” to where I am happy with the results. Most of my problem in designing the front garden was in trying to put in plants I liked or wanted in my garden that were totally unsuitable for the growing conditions.

Bad mistake and shame on me. There are certainly a dizzying number of plant species available…some of which are totally suitable for what I had to work with. I just had to wrap my head around this factor and start looking for those plants. Sure as day follows night there would be some species in this category that I would absolutely fall in love with.

Here is a partial list (Part I) of what is working in my Zone 7a, tough dry shade garden in the Pacific Northwest region.

Starting off…

Rhododendrons. I have five or more and sorry, I do not know their names. They were already in place in the garden and the tags are long gone…if they ever had tags. I have to water them religiously in the heat of the summer but the rewards are worth it.

Other shrubs worth their salt in my garden…

Kerria japonica ‘Pleniflora’. This is the deciduous, yellow double-flowered, or pom-pom, kerria. It absolutely thrives in shade and does not mind competing for water. Sterile, it will not throw seeds all over but it is does produce new branches from the root crown every year so an annual thinning of one-third of the branches overall is beneficial. The tall, green, bamboo-like stems give great winter interest.

Leucothoe fontanesiana ‘Rainbow’. (Dog hobble, drooping laurel or switch ivy.) I actually have a love/hate relationship with this evergreen shrub but this is because it is crammed in between the kerria and a viburnum and cleaning out the fallen maple leaves in the fall is a nightmare. They refer to leucothoe as an erect shrub but it better suits its “drooping” common name. The varied colours on the leaves are a bonus, plus it is evergreen. And it also effectively shades out weeds.

Viburnum x burkwoodii. Third shrub in this close grouping beside my Acer saccharinum (silver leaf maple). Another evergreen, it helps hold interest through the winter, albeit its shape has been described as “lax”. While it may prefer full sun, it is highly tolerant of almost complete shade, although at the expense of more blooms. I can attest this particular species of viburnum is resistant to the dreaded viburnum leaf beetle.

Weigela. I have five because they do well in my tough conditions. The old-fashioned Weigela florida with its red tubular flowers performs the best which is not surprising. Specially bred cultivars do tend to be a little less robust than their parents. But still, Weigela florida ‘Variegata’ is doing quite well, especially since I moved it into a sunnier locale. I love this one’s delicate pink tubular flowers, as do the hummingbirds. (Warning: weigelas do prefer five or six hours of sun if you can give it to them.)

Also moved my dark-leaved Weigela florida ‘Alexandra’ (Wine and Roses™) for the same reason. Those chestnut tree (Aesculus hippocastanum) branches refuse to stop growing outwards and into what was once sun-filled garden space.

My last two weigelas…I absolutely love the dwarf version of Wine and Roses™, Weigela florida ‘Elvera’ (Midnight Wine™), which also has the luscious dark leaves. Great to tuck into a small space as it only grows to a maximum height and spread of two feet.

And finally, my pride and joy…Weigela florida ‘Briant Rubidor’, a yellow-leaved specimen with deep red flowers. This one best suits a shadier spot where it absolutely shines where it only gets a brief caress of morning sun.

Want roses? I can attest that Rosa glauca, a dark-leaved species rose, can handle tough. It will not attain its full lusciousness but does well enough to be an asset in a hard-to-grow-in garden bed with the requisite six to eight hours of sun. Like in my street-side border in front of the chestnut and silver-leaf maple trees.

Rugosa roses also do well…particularly those in the Pavement series which were specially bred for along the median of the Autobahn in Europe. These get hot afternoon sun but are planted in terrible soil in a bed full of tree roots. And they still throw out a ton of fragrant blossoms throughout most of the summer…if I keep them dead-headed. Neighbours and visitors down our street enjoy the hedge of Rosa rugosa shrubs all along the front of our property. Another bonus: the large resident deer leave these roses alone.

Not to be left off the list are the spireas. I have three: ‘Goldmound’, ‘Goldflame’ and cutleaf spirea. All are worth their salt as they thrive well in tough, dry areas. But they too will benefit with some sun. Placing them at the very perimeter of the tree canopy will give you good colour in the gold-leaved cultivars.

So ends Part I of “Tough Plants for Dry Shade”. Part II to follow. Stay tuned.