10 BEST & WORST shrubs for Central Alberta

Posted by shane - December 7, 2011 - Shrubs - No Comments

A rose in July in Calgary

One of the first books I bought and read when I became a Prairie arborist was Lois Hole’s Favourite Trees & Shrubs.  I still use it from time to time.  It became the bible for woody plant selection and information in the early days of my career, before I had many seasons of experience and observations with hardy trees and shrubs.  I’ve learned a lot since then, and my ideas have changed.  In fact, they continue to change each year.

Simply, many shrubs that are commonly planted here in Alberta don’t really work.  Sure, technically they are hardy, but what does that really mean?  It means they’ll “survive” our winters.  But do we want our shrubs to merely survive, or do we want them to thrive?  The past two long, cold winters have changed the way I think about some of the toughest shrubs, leaving a few champions, and a lot of losers.

Many garden centres, especially the seasonal ones that are set up at grocery stores and wholesale outlets, carry a host of plants that will not survive in Central Alberta, which  is Zone 2b to 3a.  They commonly carry zone 4 and 5 (ie. Okanagan), and sometimes you’ll even see zone 7 plants (ie. Vancouver Island.)  Unless you have an indoor solarium, forget it.  These won’t make it.

Here are 10 hardy shrubs to AVOID planting and why

1) Boxwood – very finicky and slow growing.  Needs a protected site, and even then, it is unreliable.  If you’re moving to Victoria, great, plant boxwood.  If you’re staying here, don’t bother.

2) Barberry – This is one of the most common accent plants in landscape plantings.  It doesn’t overwinter well, and most specimens look rough at best.  Too bad, because there are a lot of varieties and a healthy barberry would have a lot of uses.  They look good in zone 5 and higher.

3) Ninebark – I used to think Ninebarks were bomb-proof.  After the winter of 2009 and 2010, I now know they’re not.  In fact, I would no longer consider planting one in my own yard.  They suffer horrendous die-back under extreme conditions.  They do seem to come back well if renovated to within a few inches of the ground in late winter.  Also, avoid some of the newer culitivars, especially ‘Coppertina.’  It is prone to powdery mildew.  I planted two in my yard and they died within a few weeks..  One of the most interesting hedges that I’ve seen was a golden ninebark hedge in Calgary.  After a hard winter, it was one of the sorriest looking things I’ve seen in an ornamental landscape.  After many years of of maintenance and waiting for that perfect hedge, it now needs to be cut back to grade!

‘Diabolo’ Ninebark in Calgary

4) Potentilla – I also used to think potentillas were among the best shrubs for hardiness.  Not anymore.  This is the number one shrub that I’ve been removing over the past two seasons.  Most look rough at best, shabby at worst, especially those plants in non-irrigated commercial areas.  I have found that they don’t renovate well, either, getting floppy and misshapen as they grow back.  I’m currently experimenting with new pruning techniques for this species.

Potentilla at its best

5) Roses (except native shrub roses)- Most of the roses I look after in customers’ yards are either dead, dying, or in very rough shape.  That surprised me, but there it is.  If you love roses, be prepared for a lot of maintenance.  On the other hand, my prickly rose bushes (Rosa acicularis) truly are amazing, and among the hardiest and most reliable plants I’ve encountered.  That’s why I named my company after them.  That being said, they are invasive and I’m forever chasing after them.

6) Purple-leaf Sandcherry – Forget it.  These are inappropriate for Alberta.  My Dad grows excellent specimens on his property in Vernon, but they are a disaster in our region.  For every nice specimen, I see 10 that are near death.  These shrubs die-back every year and once the deadwood is removed, it is difficult to rebalance what is left of the shrub.  They persist, but they do not thrive.  Please avoid.

7) European Cranberry (V. opulus) – Those cute little round cranberry bushes are messy-looking things in winter, sensitve to shaping, and prone to powdery mildew in mid-summer.  One of my least favourite shrubs.

8) Spiraea – I have no landscape use for these plants.  They grow great on the Coast, but here, expect annual dieback and unsightly plants.  Many of the specimens that I’ve encountered this year need to be removed and replaced.  High maintenance and marginal.  Try something else.  Once again, there are definitely exceptions, and some people tell me that they grow some great spirea.

9) Weigela – I have yet to see a really nice specimen.  Too bad, because the flowers are really beautiful.

10) False Spirea – You might just as well plant Canada thistle and quack grass in your yard.  Terrible, invasive, unattractive plants.  If you decide you need these in your yard, make sure they are well contained and that their roots won’t spread.  They are tough to get rid of once they’re established.  They burn well when dry and that is my favourite use for them.  This is the plant you give your in-laws for their gardens!

And now, the CHAMPIONS of the shrub bed

1) Dwarf Korean Lilac (Syringa meyeri ‘Palibin’) –  Year after year, I love this plant.  It is supremely hardy and tolerates abuse.  The flowers have an intoxicating fragrance and the leaves make this plant my favourite for topiary and formal hedging.  Also makes a great specimen planting.  Beware, they can get much bigger than they’ll tell you at the garden centre.  I’ve seen a few as tall as 6′ and about as wide.

2) Common Lilac & French Hybrids (Syringa vulgaris) –  The good ‘ol standby.  Bomb-proof.  Nice flowers and scent.  And lilac produces what is arguably the most impressive-looking, formally sheared hedge.  Common lilac is somewhat high-maintenance because it suckers profusely.  But kept in check, an excellent shrub as a specimen in a small yard, or as an atttractive screen.  The French hybrids do not sucker and are also very tough shrubs.  Lilacs are disease resistant, but can be prone to attack by lilac leafminer in some areas.  Leafminer can be controlled with systemic sprays in late May.

Lilac hedge in Ponoka

3) Nanking Cherry (Prunus tomentosa–  After a long, drab winter, the early blooming pink blossoms of the Nanking are a welcome relief.  These shrubs are not low maintenance, but properly groomed specimens are an excellent addition to the garden or shrub bed.  I love picking the berries when I’m pruning on a hot summer day.

4) American Highbush Cranberry – Get the species, Viburnum americanum.  Some of the cultivars are prone to aphids.  The species is better.  Cranberry has beautiful foliage, nice form, excellent flower and berry display, and fantastic fall colour.  It’s a four season plant and one of my favourites.  I’m also one of the few people that likes the smell of cranberry in the fall.  It reminds me of growing up in the woods when I was a kid.

5) Currants (red, pink, alpine, golden, gooseberry – Ribes spp.) – These are not showy plants, by any means, but they are very tough and produce nice fruit.  Their interesting foliage has a place in a mixed-texture garden, and they lend themselves to intensive pruning and interesting forms.  If you are growing gooseberries or currants for their fruit, beware the currant fruit fly, and make sure you apply an insecticide at the right time, normally when the flowers begin to wilt.  If you miss the timing, every single fruit will have a little hole, with a nice little fly larva.  My favourite plant in my garden is a red currant.

Red Currant in Sylvan Lake

6) Hydrangea cvs. – A few years ago I would never have considered hydrangea to be one of the top shrubs, but I’ve since learned over the past 3 years certain varieties are excellent, tough, and insect- and disease-resistant.  I prefer ‘Vanilla Strawberry’ and ‘Little Lamb’, although a properly placed ‘Annabelle’ is a lovely choice.

7) Saskatoon – We use various cultivars of Saskatoon in most of our designs.  They are a 3-season plant, with great spring flowers, nice fruit in summer, and excellent fall colour.  I prefer the shorter varieties because they work in small yards and gardens, or for mini-orchards, popular among urban homeowners.

8) Mugo Pine (Pinus mugo) – A reliable standby. Most specimens I encounter, while neglected, are healthy. Planted in good soil with occasional maintenance, these plants are bomb-proof, versatile, and lend themselves to very creative pruning styles.  The past few years, we’ve switched from the standard mugo pine to the dwarf mugo pine, becuase it is much more compact and easier to maintain.  Unless your dog pees on them, they are pretty bomb-proof.

9) ‘Blizzard’ Mockorange – One of my favourite shrubs for sunny or shady spots.  I include this plant in many planting schemes.  It leafs out early in the spring, suffers little to no die-back, and produces an excellent display of fragrant flowers in late June to early July.

10) Powderface Willow (Salix commutata ‘Powderface’) – Available at Bow Point Nursery in Calgary, this is fast becoming one of my favourite shrubs.  It has incredible blue-grey foliage that really stands out in the shrub bed.  It is extremely tolerant of dry, hot places, and it thrives in the worst possible growing location in my yard.  It needs sun, however, so don’t put this plant in the shade.

(c) 2012, Shane LePage, Wild Rose Garden & Tree Service, Red Deer, Alberta