Caragana (Caragana spp.)

Posted by shane - December 21, 2010 - A-Z Plant Maintenance, Shrubs - No Comments
 Common Caragana – Caragana arborescens

‘Sutherland’ Caragana – Caragana arborescens ‘Sutherland’

Fernleaf Caragana – Caragana lobergii

‘Walker’ Weeping Caragana – Caragana arborescens ‘Walker’

Pygmy Caragana – Caragana pygmaea

The various caragana species are quite different with respect to their maintenance requirements.

Common Caragana

The familiar yellow blossoms of Common Caragana

In cities, this is most commonly found as a hedging material.  In the country, it is often planted as a windbreak and completes its life without any pruning work.  I have a love-hate relationship with this plant.  A healthy specimen is a beautiful addition to an ornamental landscape.

Pruning Time: For hedges, prune caragana the way you would any hedge (see hedging).  If the hedge needs to be reduced in width or height dramatically, shear in late winter before the buds break so as to not stress the plant any more than necessary.  A second trim may be required in late June, after the growth flush.

Specimen common caraganas can be treated in much the same way as a common lilac as they both readily produce lots of suckers each year.  They also have similar mature heights and forms.  Caragana is tolerant to renovation and old, diseased heges or specimens can be but back to 4” from the ground in late winter.  Provided that the shrubs have a well established root system, they will recover as a new, healthy shrub or hedge.

Common caraganas are prone to powdery mildew in the summer, especially on the north side of the shrub or hedge that receives little light.  I avoid trimming hedges that are infected with powdery mildew and recommend a dormant season shaping as opposed to summer.  Homeowners can buy Neem oil (marketed as a indoor plant cleaner), mix as directed into a backpack, or similar sprayer, and treat infected plants.  Neem has been reported to arrest powdery mildew within 24 hours.  Commercial fungicides are also available.  Contact a professional pesticide applicator or arborist for advice.

Irrigation & Fertilization: Caraganas are extremely resilient shrubs and can withstand hot, dry, windy conditions, planted in poor soils.  Irrigation and fertilization are generally unnecessary.  All caraganas have the ability to fix nitrogen from the atmosphere via bacteria on their roots systems.

 

Sutherland Caragana

This species is a nice small tree or large, upright shrub.  Sutherlands do not sucker and make nice specimen planting in tight areas.  They are generally very hardy and require minimal maintenance.

Pruning Time: Dormancy is ideal.  Since Sutherlands usually only require a few cuts, anytime of year would be acceptable.

Structure: Sometimes, these trees have self-destructive branch attachments and if not corrected early, will require bolting to stabilize the co-dominant limbs (See Bolting and Cabling).  Subordinate co-dominant stems while the plant is young.  Once established, remove the weaker of obvious crossing and rubbing branches.  These trees are often planted too close to the house and usually require come clearance pruning off the roof.

Health: Remove deadwood every one to two seasons to maintain healthy-looking shrubs.

Irrigation & Fertilization:  Generally unnecessary.  As ‘Sutherland’ caraganas are not quite as hardy as the common variety, water shrubs during extended dry periods in summer.

Fernleaf Caragana

Fernleaf caragana in the landscape

A very attractive, underutilized species.

Pruning Time: Dormancy is ideal.  These trees require minimal maintenance and can be pruned anytime of year.

Structure: Train early to avoid co-dominant stems and included bark in branch attachments.  Fernleaf caraganas often break apart during snowstorms, leaving a disfigured, unbalanced specimen that is best replaced.  If not properly trained from planting onward, bolting is usually required, in order to maintain the structural integrity.  Once established, trees require minor structural pruning to remove crossing braches, or to clear limbs off of a fence or structure.

Health: Remove deadwood every one two seasons for healthy-looking trees.

‘Walker’ Weeping Caragana

Commonly found in the landscape

While this shrub has an interesting form and is definitely useful in landscapes, it is the least hardy of the caraganas.

Pruning time: Dormancy is preferred.  Anytime of year would be acceptable as these shrubs require only minimal maintenance.

Structure:  Remove upright shoots to encourage the weeping habit of the plant.  Remove the weaker of crossing and rubbing branches.  If planted too deep, or if the plant is injured near the base, the rootstock will sucker.  If this happens, remove suckers as they appear.

Health: Remove deadwood each season.  ‘Walker’ caraganas often become infected with powdery mildew in the summer, especially during warm, moist weather.  Treat as you would for common caragana above.

Irrigation & Fertilization: Provide fertilizer with micronutrients if the plant shows signs of deficiency.  Water plants during extended dry periods.

(c) 2010 Shane LePage, Wild Rose Garden & Tree Service, Red Deer, AB