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Rhododendron and
Azalea News

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Summer/Fall 2010  Vol. 13  No. 2
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Plant Tips


How to kill your rhodies


Jerry Rock, of the Pilchuck Chapter and recently awarded the Bronze Medal, is often asked about planting and caring for rhodies.  They say, "I planted it...and it just died!"

Jerry says, This is what generally happens:

  • The rhody was planted below ground level.
  • Planted in a sump...where drainage was poor.
  • Added fertilizer right up to the trunk.
  • Added thick, fine mulch of sawdust or bark right up the trunk.
  • Weeded with the hoe right up to the trunk.
  • Planted in hot shade of any kind.

Are you having problems?  Consider these six simple, very simple guidelines...Then correct yours, and see if Jerry's experience is a winner.


A Dr. Rhody Question: Best time to plant.


Dear Dr. Rhody,

Read in your column earlier that you suggest October is the best time to plant Rhododendrons.  I purchased ten new plants...but somehow I have not yet had the time to plant them.  Am I too late?  What do you suggest?

 Signed "Late"

Dr. Rhody replies...


I did indicate that the very best time to plant or transplant Rhododendrons...or most other woody October.  In areas that usually doesn't have extremely cold weather you can plant anytime during the winter as long as the ground is not frozen.

Make sure you provide material to make your soil porous and able to drain easily.  One advantage to planting during a rainy season is an opportunity to see where not to plant...areas of standing water should be strictly avoided.

So put on your raincoat, get your shovel, and plant those rhododendrons.  Then wait until Spring to enjoy the blooming of our favorite plant.

-- Dr. Rhody



Rhodos as lime haters?


"Lime haters" is an epithet usually found in books and articles on the cultivation of rhodos and azaleas.  The term is correct when applied to caustic compounds...such as agricultural and masonry limes...when are absorbed quickly...but should not be construed to mean calcium.

All plants require calcium.  Because they are the end-products of a complete nutritional process, organic fertilizer such as bone meal, incorporate calcium which becomes available slowly.

Rhodos and azaleas often exist in a nutrition-poor soil in which their ability to take up calcium sustains them.  In a mixed fertilizer they tend to take up the calcium first...with the exception of dolomite...from which they take the magnesium before the calcium.

what writers say...


Several writers have dealt with this phase of cultivation with the intent of showing the safe use of calcium.

  •  Judith Berrisfold says, "Rhodos and azaleas have too great an appetite for lime when they can get it and indulge themselves over-freely to the exclusion of other foods.  Like all plants, rhodos need some calcium...but because they live in nature on acid soil with a low free-calcium content, they are adapted to take up all the available calcium."

  • Peter Cox indicates, "A surfeit of one element may tie up others and make them (i.e. iron) completely unavailable to plants, so unhealthy foliage with chlorosis may occur."  Mr. Cox further writes:  "Calcium and magnesium are associated widely in various dolomitic and serpentine-type limestones (hydrous magnesium silicate) and this accounts for some of the reported cases of rhodoes on limestone.  As they are tolerant magnesium, which is a related element, this gets assimilated into the plant instead of the calcium."

experimenting with various soils..


After experimenting with various soils in England...some including masonry rubble and spent mushroom British gardener concluded:  "Calcium is not toxic to rhodos unless there is gross disturbance of the general nutrition, for instance, by raising the soil pH."

lime-tolerant species...   

Lime-tolerant species include:  ciliatum, sanguineum (ssp), didymium, hippophaeeoides, hirsutum, scyphocalyx, williamsianum, and mackinoi.

--North Island Newsletter and reprinted from the California Chapter with an unknown date.


Fall clean up


Here are some wonderful tips for cleaning up for Fall...and each one comes from the ARS secretary, Kath Collier.  She is doing a fantastic job in her new position and is always loaded with the most unusual ideas.  She calls the following "In the Garden 101".

too many leaves?


By now many of the trees have lost a great deal of their leaves.  My garden is covered!!  The push is on now to get the dead leaves raked and piled, round up, and tucked in between layers of compost.

This bit of garden hygiene is not just something to make the garden look better, and paths less slippery.  It is needed to protect the plants from damage that can occur from insects hiding in the know like root weevil larvae...and other things that can be rally bad in the garden.

It is also useful in maintaining soil pH, as the leaves of some plants like big leaf maples can create a nearly impenetrable and highly-acidic blanket.

what to do in simple steps...

  • Take care to not collect diseased plant materials with the healthy stuff!  Some of this material may need to be thrown away or burned.  Diseased stuff just doesn't belong in the compost pile.

  • To make the grinding process simpler, I like to pile the dry leaves in the back yard or along the driveway where the wind won't catch them as much.  The grass is preferable and significantly less messy.  Once I have a good pile I bring out the riding lawn mower; and slowly drive across the leaves filing the three large collection baskets in the back.  Because of the volume of material it is essential to check the baskets frequently.

  • Once they are even close to full, I pull along the compost bins and begin the process of re-layering the piles and lacing them with the crushed leaves.  Typically, I will layer about an inch of crush leaves over about three inches of compost, followed with a layer of coffee grounds and other green items.  Repeat until you can no longer lift your pitchfork.  Some years I will layer in sawdust and horse manure into the mix.  It is critical to get the piles good and steamy over the winter.

  • If your timing is bad and you only have wet leaves...well, that is the pits...because they are very hard to crush, and can form a hard water proof layer in the compost...essentially not break down for a year or two.  In this case, keep the leaf layer very thin and not solid, beef up the materials that will help the pile heat up (like various manures), and plan on turning the piles more often during their cooking period.  It is almost better to wait for dry leaves than to go for this wet method.

  • This is also a good time to look for damaged shrubs and trees, down fruit, or other places for insects to hide, and bee nests.  If you find a yellow jacket nest in the ground (which is fairly common), place a clear bowl over the whole for several days.  The yellow jackets only create one entry, will not dig another, and will starve themselves.

  •  The sun is shining, leaves are dry, and rustling my name...time to break out the rake and...get cleaning!

Thanks, Kath!  There's always something to do...and work outside can be made easier by sharing thoughts.


Getting your garden ready for Winter


Jeanne Kinney of the Shelton Chapter has a few comments to share about getting ready for winter as most realize it is time to wrap 'up' another gardening season.  There is always a "to do list" or a similar "honey-do-list"!  Her primary challenge:

water, water, water!


Very important for trees and shrubs, especially if you have had a dry summer.  Evergreens continue to lose moisture during the colder months, and shrubs with moister soils (but not waterlogged) survive better than those in drier soils. 

droopy leaves cry, a drink, a drink...


Some foliage droop is normal in dry weather, specially on warm afternoons...but when leaves still show signs of drooping in early morning, the plants are showing a need for water and should receive a good soaking.

When air temperatures go above 95 degrees (or even lower for alpine types), rhododendrons and azaleas appreciate a misting to prevent desiccation of their foliage.  In climates, water or misting of foliage during warm days in the spring or on windy days when the roots are still frozen, will help to keep rhododendrons in good condition.

importance of mulch...a best in every garden!


A year-round mulch of some type of organic matter is desirable to conserve moisture and eliminate the need for cultivation.

Because of their shallow roots...little or no cultivation should be done around rhododendrons.  Weeds should be carefully pulled...or in extreme cases shaved off with a sharp hole.

A fairly deep mulch of leaves, pine needles, chips, bark, or other organic material will practically eliminate weed growth.  Suggested that meat moss should not be used as a mulch because it sheds water when it dries out.

The coarser the mulch...the better!  Why?  As water and air are admitted the mulch still retards evaporation by providing shade and reducing wind velocity over the roots.  A mulch also helps to reduce temperature extremes in the root area.


Winter hardening rhododendrons


Eleanor Stubbs of the Portland Chapter has been doing a little snooping around in old ARS Journals and has found an interesting article on Winter Hardening Rhododendrons which she thinks may have been written by P.H. Brydon.  Listen:

During the bleak sunless months of Winter, most rhododendrons pass unnoticed in the garden.  Since the first early frost of Autumn, the large leaves of the Chinese species seem to droop and draw closer together.  The arrival of cooler weather parallels the seasons of their native home in the high Himalayas.  To this prelude, the plants treat as they have for ages in the past.

Since the last flower buds were formed in late Summer, the plants have done little to all outward appearances.  The present period, during the winter months finds an almost eclipse of cellular activity.  Yet, it is wrong to state that the plant is dormant, for the underground even in the dead of Winter, new roots are constantly forming.  I have observed plants...both large and small...being moved throughout the Winter, and almost always the outer perimeter of roots is new developed.  If one has not the occasion to move plants, the new root activity can be easily observed by removing a few inches of mulch.  There will be ample evidence...even when the mulch is frozen that the plant is not dormant, for in the warmer earth nature seems to forge right ahead.

new roots in Winter...


The fact that this process of putting forth new roots goes on most of the Winter must plainly mean that the plant is taking what nourishment and moisture it needs...when it needs it!  It can hardly be argued that the plant is only establishing its roots into new...A plant will not manufacture a root system for the future...but instead just enough for the requirements and well-being of itself for the present.

water still needed in Fall...


For many years nurserymen and growers...and gardeners...have recommended the withholding of water during the later Summer months.  This supposedly was to afford a 'hardening off' period for the forthcoming bout the plant would have with the coming Winter.  Many growers and gardeners alike follow exactly this procedure, and the last week of August when the plant should be storing food...all sources of moisture are stopped.  I have seen plants languish...their foliage drooped and, in some instances, actually burned during this treatment.

is the plant really hardened?


What is taking place within the plant?  All available moisture has been expirated through the leaves and reserve sugar, plant food, and moisture are also used up.  If the drought is prolonged, all the reserve the plant has stored is thrown into the battle.  True...the plant is dried out, the food reserves are gone, and the plant is hardened...but I don't think for a rigorous cold...

keep rhodies growing successfully...


Any rhododendron plant that is worth growing at all...should be grown as well as the gardener can possibly accomplish the feat.  Ample and regular irrigation will keep the plant growing well during the dry months of Summer and Fall.  When Winter does enter...the rhododendrons will stand great drought when once established, it must also be remembered that rhododendrons also abhor and evade the arid regions of earth.



Practical tips for fall and winter...


Norma Day, of the Mason-Dixon Chapter, wants to share some tips she has learned about getting ready for fall and winter.

  •  Make sure plants have been thoroughly watered.

  •  Using a room rake to "fluff" your mulch will allow air to circulate.

  •  Start a notebook with information about dates 0f cuttings, fertilizing, insect spraying, haircut for cuttings and distribution.

Norma shares she has journeyed for six years and finds it very helpful!  It's works...also a large monthly calendar will do a similar trick!


Fall is for pumpkins


Fall is just around the corner and the leaves are already turning their beautiful shades!  Nothing is more beautiful than to take a ride in the country and see the changing colors...and see the pumpkins.  Those bright orange things...even water towers in some parts of the country are painted a bright orange to celebrate the coming season.

Pumpkins are believed to have originated in North America.  Seeds from related plants have been found in back to 7000 to 5500 BC!  That's right...some 5000 to 7000 years ago!

References to pumpkins date back many centuries.  The name pumpkin originated from the Greek word for "large melon" which is "pepon."  "Pepon" was changed by the French into "pompon."  The English changed "pompon" to "pumpion."  American colonists changed "pumpion" into "pumpkin."  (Now, that's a nice lesson in words!)

Native American Indians used pumpkin as a staple in their diets centuries before the Pilgrims landed.  They also dried strips of pumpkin and wove them into mats.  Indians would also roast long strips of pumpkin on the open fire and eat them.

When the white settlers arrived, they saw pumpkins grown by the Indians and pumpkin soon because a staple in their diets.  As today, early settlers used them in a wide variety of recipes from desserts to stews and soups.  The origin of pumpkin pie is thought to have occurred when the colonists sliced off the pumpkin top, removed the seeds, and then filled it with milk, spices, and honey.  The pumpkin was then baked in the hot ashes of a dying fire.

--Mason-Dixon Chapter NewsNotes, Fall 2009

Fall and Winter means THAT white stuff


Fall is here and winter follows shortly behind...and along with it...for many people...SNOW.  The Eugene Chapter's Newsletter has a few comments worth thinking about...and DOING!

  • A trick to keep snow off of the blade of a shovel:  Take some kitchen spray, such as Pam, and spray both sides of the blade.  The snow will simply fall off without any fuss!
  • Keep small tools stuff in an pot and get a magnetic strip for the hardware store and mount it on your worktable.  Easy to identify.

Something to think about...a feeling of Fall


I feel fall in the air
       as it comes tiptoeing in
       close on the heels of late summer.
       sending signals
       to prepare for shorter days
       and longer nights.
I sense a growing awareness
       of a change in seasons
       as colors begin to dot the trees
       along the streets where I travel,
Faint yellows among the greens,
       a twinge of gold
       with hints of red
As cooler nights shake the leaves,
       encouraging them
       to leave their parent limbs
       to which they have clung
       so happily
On so many warm sunny summer days.

-- John Fry, Eugene Chapter

Many thanks, John, for making us appreciate the beauty of Fall and to make us aware of meaning of the change of seasons.


American Rhododendron Society
Executive Director: P.O. Box 525,  Niagara Falls, NY 14304
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