Saturday, April 11th, 2009...4:50 pm

Encore Azalea – Possible Cold Damage

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12-20-08 - Encore azalea by jennymunro (on flickr)

12-20-08 - Encore azalea by jennymunro (on flickr)

TheGardenLady received the following question about Encore Azaleas.

We live in Belews Creek North Carolina. We planted 3 Encore Azaleas last spring, they bloomed all summer and fall, they lost their leaves in the winter and now we have no leaves, or buds. The limbs are bare but green, I have cut several and checked for dead signs but have found only green. This is spring and was looking foward to seeing their flowers. Any help will be appreciated.

Here is the answer from Encore Azaleas.

Cold damage can take a while to show up, causing the bark to split which interrupts the transport of water and nutrients throughout the shrub. Loss of foliage, especially during extremely cold weather, may occur, but doesn’t necessarily mean that the shrubs won’t bounce back.

If you have not already fertilized this spring, use a slow release granular fertilizer that is right for your area. Make sure the mix is well-balanced – the three numbers on the packaging are the same or similar. These numbers indicate the amount of nitrogen (promotes plant growth and for foliage), phosphorus (promotes blooms), and potassium (strengthens roots and stems). If your fertilizer contains more nitrogen than phosphorus, your azaleas will concentrate on growing rather than blooming.

Cold Hardiness
In a recently completed three-year cold hardiness study undertaken by the University of Tennessee, 19 of the 23 varieties of Encore Azaleas trialed in USDA Zone 6 demonstrated positive results.

Five varieties (Autumn AmethystTM, Autumn CheerTM, Autumn RoyaltyTM, and Autumn RubyTM and Autumn TwistTM) consistently exhibited solid cold hardiness throughout Zone 6A.

Autumn Sangria and Autumn Sweetheart showed success in protected locations in Zone 6A.

In Zone 6B, 18 varieties consistently exhibited solid cold hardiness:
Autumn AmethystTM, Autumn AngelTM, Autumn CarnationTM, Autumn CarnivalTM, Autumn CheerTM, Autumn ChiffonTM, Autumn DebutanteTM, Autumn EmbersTM, Autumn EmpressTM, Autumn MonarchTM, Autumn PrincessTM, Autumn RougeTM, Autumn RoyaltyTM, Autumn RubyTM, Autumn SangriaTM, Autumn SunsetTM, Autumn SweetheartTM, Autumn TwistTM (Autumn BelleTM, Autumn MoonlightTM, Autumn SundanceTM were not trialed.)

As your Encores mature and get more established in their environment, they will be better able to withstand cold temperatures. Young plants are more susceptible to sudden, drastic drops in temperatures, and sustained cold weather (25 degrees or below).

Cold Protection
Mulch well (about 4 inches deep) in the fall. Reduce water for a month or so before the first frost. Then, after a couple of hard freezes, water well to provide moisture. This will help the plants to go dormant, or “harden off”.

As you would with any outdoor ornamental plants, Encore Azaleas may need some extra protection during sudden freezes and extremely cold weather. Sudden, drastic drops in temperature are more damaging than a gradual decline, especially to newly planted shrubs.

Burlap, old blankets, or sheets (any cloth material) can be used to cover upper plants. It is recommended that you drive stakes in the ground around your Encore and drape the cloth cover over stakes. Foliage in contact with the cover can be injured, so try to minimize cover contact with plant.

I hope you find this information helpful; keep me posted on your progress and let me know if you have any other questions or concerns.

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4 Comments

  • why isn’t autumn coral in the list above?

  • Autumn coral is on the list in Encore’s Digital Magazine http://www.encoreazalea.com/encore/stat_collection.cfm.

    Here is what it says about Autumn Coralâ„¢ (Rhododendron Hybrid)
    Azalea x ‘Conled’ PP# 10568

    Great as a foundation plant, this variety’s soft coral pink flowers, dotted with bright fuschia centers, bloom profusely throughout the
    summer and fall months.

  • I’m planting Autumn Coral Encore Azalea in Zone 5, St. Louis and will follow suggested mulching program this fall. Has anyone had success with this or other Encore varities in Zone 5? It’s hard to believe that this evergreen azalea wants 4-6 hrs of direct sunlight. StLouis summers are brutally hot and very sunny overall. Standard evergreen azaleas usually perform best here in east or north exposure or under large shade trees. Any thoughts on amount of sunlight?

  • Any additional suggestions for planting Encore Autumn Coral in Zone 5 (St. Louis)?

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