Juniper

Posted by shane - December 22, 2014 - A-Z Plant Maintenance, Shrubs - No Comments

Juniperus chinensis cvs(‘Gold Coast’, ‘Mint Julep’, etc.)

Juniperus horizontalis cvs(Horizontal juniper and cultivars)

Juniperus communis cvs. (Common juniper and cultivars)

Juniperus scopulorum cvs(Rocky Mountain juniper and cultivars)

Juniperus sabina (Savin juniper and cultivars)

These is arguably the most ubiquitous landscape shrubs in Alberta.  I’m not a fan of juniper.  I think the only reason we plant them at all is because we are zone 2b/3, and they are some of the few plants that give us a bit of green year-round.  My plant identification instructor in college said they used to refer to juniper as Jupiter in the landscape trade, because that’s where they wanted to send them most of the time.

Sheared Juniperus scopulorum in Red Deer.  S. LePage photo.

Sheared Juniperus scopulorum in Red Deer. S. LePage photo.

All plants have their place, and I have seen many excellent well-placed junipers in my career.  I like them best in gardens with an oriental theme, as they work well with mugo pine and sheared dwarf Korean lilac in a mixed planting.  The also make a useful ground cover in some situations.  I also like them in a planted in a tight cluster with other conifers with the intent of creating a large, rolling topiary.  The upright, Juniperus scopulorum varieties make excellent topiary specimens and look best after many years of shearing.

‘Calgary Carpet’ juniper is a very commonly used ground cover.  We don’t recommend planting this in an area close to lawns or quack grass, as the grass invades the juniper and is very difficult to weed out.  As a result, many ground covers look unsightly and over-run.  Our preference for a ground cover is ‘Icee Blue’, with a stunning, bright, silvery-blue foliage.  It is very attractive in a mixed perennial planting and very hardy.

Foliage of low-growing 'Icee Blue' juniper.

Foliage of low-growing ‘Icee Blue’ juniper.

Exposure

Full sun to part-shade.  Depends on variety.  Be sure to check the tag before purchasing a particular variety, and make sure the plant is hardy to zone 3. Zone 4 junipers will not work here.

Pruning Time

I prefer to shear Rocky Mountain junipers after the growth flush, from mid-summer to fall.  That way, you can have a perfectly shaped plants until the following June, when they start to put on new growth again.  Minor pruning on other junipers can be done anytime of year.

 

Pruning

Most junipers need minimal pruning, and rather than trying to contain a juniper, it is best to select a planting site that will be large enough to accommodate the mature plant.  There are few things that look as ugly in the landscape as a hacked-up juniper cut back because the owner is trying to keep it in a shrub bed and out of the way of the lawnmower.  Make the bed bigger, don’t try to make the juniper smaller.

If a low-growing juniper must be pruned, use hand pruners, not shears or power hedgers.  Prune individual wayward branches to correct the overall form.

Crown Reduction and Shaping

For upright junipers only, such as ‘Wichita Blue’, ‘Moonglow’, and Rocky Mtn. Juniper, lightly shear each year from mid-summer onward.  I do not recommend shaping on other juniper forms.

(c) 2014 Shane LePage, Wild Rose Garden & Tree Service Inc., Red Deer, AB