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Plant Tips

Dear Dr. Rhody...bugs on seedlings?

I was present at your presentation on growing rhododendrons from seed during the 2001 Eugene Convention. I ordered seed from the seed exchange and began to grow seedlings.

The first year everything grew fine and had no problems. This year have noticed many, many little gnat-like bugs crawling all over the containers of seedlings and flying around the area. Are these bugs a problem? Will they damage my seedlings?

- Fellow Grower

Dr. Rhody responses:

Dear Fellow Grower...Indeed, you have a problem! Fungus gnats are what you are describing. They are a major pest. Although they appear small and harmless...they can destroy your seedlings.

fungus gnats...

Fungus gnats eat the root of small seedlings. Unfortunately, I learned the hard way. I grew seedlings for several years and had good success. The year I ordered and planted some very unusual and hard-to-find species selections, I lost over half of what I planted...thanks to the fungus gnats. I almost gave up growing seeds.

there's hope...

There is hope! Some steps you can take to reduce your problem. Sticky yellow tags are a good trap and a good indicator of fungus gnats.

I believe...not everyone will agree...peat moss contributes to the proliferation of fungus gnats. I think the gnats really love peat moss. Moisture is also a factor which encourages fungus gnats...and, of course, moss and fungus help, too. I am better able to control these variables with coconut fiber. It works for me.

some chemicals will work...

In order to eradicate fungus gnats there are a variety of chemicals that will help. Dursban will help kill adults, if you choose to use it. Gnatarol is a product that is very safe...but you have to use it very frequently.

Cleanliness in your seed room can also help to cut down on gnats. There also are some new insect growth regulators available that will work...if you are certified to use them.

be vigilant...

Be vigilant...get rid of the gnats...and your seedlings will grow to become beautiful rhododendrons some day!

 

Rhododendron garden tips...

 

Here are a few suggestions from the North Island rhodo experts on how to be successful in your garden:

  • No more fertilize after the end of June.
  • Finish deadheading everything you can reach.
  • Spray plants that are affected by root weevils...they only bother certain rhodos never touch the rest.
  • Cuttings of deciduous azaleas should be taken as soon as the stems harden off a little...late May or early June.
  • Cuttings of many other shrubs...including rhodos...can be taken after July 15...depending on the weather. A good rain or watering a day or two before, is necessary.
  • Rhodos need water during the summer...in order to initiate flower buds for the next year.

Some of the points above may not match the calendar...but they are worth taking note of...and you still may want to use some. Good Luck!

 

Bug-busting tips

Jerry Baker, a Master Gardener, has given the world wonderful tips on gardening and shows us again some things we should look for in our garden...and how to correct them.

When strolling through your flowerbeds and gardens, it is important you keep your eyes open for insects. Here are my tried and true bug-busting tips that will keep those wiggling and winged warriors away from your annuals, perennials, and flowering shrubs.

garden thugs are bullies...

That's right...they always pick on plants that are weaklings. So fight bugs the best way...with a good, preventative maintenance program. Give your plants plenty of sunlight and water...feed them well...and weed them regularly. Healthy plants will be able to fight off most bugs without any additional help.

aphids...

Aphids like the cool, dark undersides of leaves. Shake them up! Let there be light! Lay pieces of aluminum foil under affected plants. Aphids are confused by increased light...and leave the leaves. Also, cut up two or three garlic cloves...and sprinkle them among your rose bushes to keep the aphids away.

earwigs...use soy sauce...

These guys like to nibble on the foliage and flowers of many plants...especially dahlias, zinnias, and hollyhock. To keep these ugly thugs from calling your yard home, you need to remove their hiding places. Any place that is dark and cool during the day is an ideal spot for them.

Trap them...by putting an inch of soy sauce in the bottom of an old sour cream container, then top it off with a thin film of vegetable oil. Put the cover on...punch 3 holes near the top of the container...set it in your garden. Throw it out whenever it is brimming with bugs!

 


Autumn calls for gardening tips

Fall is around the corner and it is a great time to plant those rhododendrons and azaleas that were not attended to this spring. The plants will concentrate on producing their root system instead of creating flowers...and they will not be subjected to the high temperatures and dry periods associated with the stresses of summer.

Here are some things to think about as you prepare for fall...followed by winter.

  • Do not fertilize any of your plants at this time. The plants' new terminal growth of leaves and bud set already produced doesn't need a nutritional boost. If anything, fertilizing now will only cause an onset of new growth that won't have a chance to harden off before the cold days ahead. Plants should not be fertilized after the first of June.
  • Check the mulch around the base of the plants...making sure it does not come in contact with the base of the shrub which can harbor insects and their eggs, such as borers. Some good mulches are those that are acidic and will not compact...such as pine needles, oak leaves, pine bark chips, pine bark shredded mulch, and evergreen branches...save your live Christmas tree, too.
  • Continue to water plants during dry periods. Soaker hoses are preferred to watering. If you have a small area, rhody addicts have extended their yards' gardening beds to accommodate our beloved collecting of these vast beauties.
  • Prune any damaged or dead branches...but do not do any severe pruning at this time. Wait until early spring. Clean your pruning tools with Lysol wipes between affected branches to prevent the spread of disease.
  • Save the leaves of oak trees. Rake them off the lawns and do not throw away these valuable resources. Consider establishing a compost pile or bin. These leaves can also be shredded with a lawn mower and used to mulch your favorite plants.

With cooler weather upon us, I feel more energized and with shovel in hand, I am ready to tackle planting and transplanting a few shrubs.

Remember to consider in years to come...just like children they outgrow their clothes and require room to grow!

Happy gardening,
Cathy Bird
New York Chapter

 


MORE and more Fall advice

Now that the days are getting short...the rhodies will start going dormant. These are some more things to think about...and repeats from other rhody experts. Because the instructions are repeated and repeated...almost to the stage of rote...the instructions should become cemented in our day-to-day activities at this time of the year.

Bill Stipe of Whidbey Island Chapter drives home the guidelines again!

  • Do not prune or fertilize now.
  • Check the flower buds which should now be formed and remove any more than one per terminal...this will assure a better flower truss next spring.
  • Check the leaves for symptom of root weevil...if they are present they leave notches along the edge of the leaves.
  • Several insecticides are approved for control, I use Talstar...generic name is bifenthrin. Apply at the base of the rhodie...which is where the weevil hang out during the day. You can also hand pick the adults by going out with a flashlight at night...and squashing them.
  • Fall is also a good time to add or renew the mulch in your rhodie beds. Add 2 to 3 inches of bark or compost.
  • It also is a good time to plant or transplant rhododendrons.
  • Revive your tired lawn by over-seeding through mid-October.
  • Sod can go in nearly any time all winter...but be sure the soil drain well.
  • Watch the nursery ads for fall clearance sales!

 


Leaves can tell the temperature!

Garth Wedemire from the Fraser South Chapter has done a little research on why rhododendron leaves...curl and droop. Here are his findings. Most interesting.

curl and droop is normal...

Leaf curl and droop is normal when rhododendrons are exposed to extreme heat, extreme cold, or drought. It is a natural reaction that helps prevent dehydration under these conditions of extreme stress. The curl and droop should go away when the extreme condition is reversed.

curling defense in cold weather...

Leaf curling in cold weather is a defense against moisture loss through the leaf surface. When the temperature drops below 35F, rhododendron leaves begin to cup and curl at the edges. At 25F, the leaves have curled so tight that half the leaf surface has disappeared and the leaves droop. When temperatures hit the teens, leaves shrivel even tighter...turn brownish-green and dangle like stiff string beans.

curl in summer...

Rhododendron leaves curl and droop during the summer months...if they lose too much water, just as other plants wilt. The pores through which the plant loses water and takes up air are located on the underside of the leaves. When the leaves curl, these pores are protected, and the evaporation of additional water is reduced. The curled leaves protect the rhododendron plant from more water loss.

a few facts...

Leaves of rhododendrons respond to cold by first drooping...then curling up.

  • At temperatures above freezing, the leaves extend at approximately right angles from the stems.
  • Just below freezing, the leaves droop downwards...but remain flattened.
  • At 25 or thereabouts...the leaves droop and curl, and by 20, they are curled so tightly that they look like green pencils. Once the temperature drops below 20, they can't curl up much tighter, and only a non-living thermometer will do.

leaf curling…a strategy...

Leaf curling is a strategy to prevent moisture loss in the leaf tissue. As the temperature rises above freezing again...the leaves unfurl and look striking in the winter garden. Perhaps, a scientific study which investigates the relationship between curling and drooping...and temperature for various rhododendrons could be undertaken by researchers.

not all rhodies curl and droop...

Not all rhododendrons exhibit this ability to curl and droop. Some like 'Unique' do not respond as dramatically as others, like 'Crest'. When it gets very cold, 'Crest' curls its leaves up so tightly that they look like thin pencils. By looking out a window on a winter day, one can determine roughly how cold it is by the degree rhododendron leaves have curled and drop. When temperatures rise, the leaves open again.

Next time you encounter a rhododendron, estimate the temperature by evaluating the curl of its leaves. You may surprise yourself with the plant's accuracy.

 

Fall for Rhododendrons

Norman Todd, Victoria Chapter, is a true-died devotee of rhododendrons...and he loves to write and write everything possible. Someone has unearthed a splendid article he wrote in the 1990s! The news editor of the Victoria's Chapter has searched the archives and the article appeared in the October 2007 newsletter...stating it was both "timeless and timely". Now, it is brought to your attention...for the fall of 2007.

In the gardens of coast British Columbia the best time to plant broad leaf shrubs and trees is the fall. In October and November, the soil is still warm, the autumn rains have begun, and conditions are the best for the development of new roots. By planting in the fall, plants will become established before the burgeoning demands of spring signal the roots to send more nutrients for swelling blossoms and expanding leaves.

unseen activity goes on...

As long as the ground is not frozen, the roots of the broad leaf evergreens are purposefully working. To the human eye there does not seems to be much going on above soil level...but the plant is still photosynthesizing. Sugars and starches are being manufactured from the nutrients the searching roots are pumping up to the leaves.

tease transplants to new location...

When a plant is dug up and replanted...or taken from a container and put in the ground...the roots are always disturbed. To assist them to grow into soil in their new environment, the roots of a potted plant must be teased apart quite vigorously so that they can make intimate contact with the welcoming environment of the new, freshly prepared home.

alert...rhodos hate too much water...

For rhododendrons this means an open, friable soil with a high content of organic matter, located in a well-drained site. Rhododendrons hate standing in water: they drown. Their roots need loose, airy, humusy soil around them.

cardinal rule: roots never go dry!

One of the best and easiest ways to give them this open soil and the right acidity is to incorporate bark mulch. Up to 50% of the mix in the planting soil can be bark mulch...not too coarse and not dust either! Many people like to use peat moss...but much of the moss available today is so fine that if it ever dries out...it is very difficult to moisten it again. Furthermore, peat moss breaks down far more quickly than bark mulch.

The number one cardinal rule for growing rhododendrons is that the roots must never go dry.

guidelines for planting...

If your soil is black, humus-rich loam, you are fortunate indeed...and no amendment may be necessary. You can plant the rhododendron as deeply as it was in the pot.

  • If the natural soil is heavy clay, then 8 to 12 cm of coarse sand should be dug in to a depth of 30 cm before the addition of the bark mulch. Composed leaves, preferably oak, can be used instead of bark mulch.
  • If the soil is heavy clay, you can plant very shallowly, bringing the amended soil higher than the soil level at which the plant was previously growing.
  • Mixing some fertilizer in the planting hole is beneficial. Avoid using animal manures that are less than a year old.
  • An excellent fertilizer you can make yourself is a mix of ground meals:
     4 part of canola
     4 of blood
     1 of bone
     1 of kelp
     plus
     2 of dolomite lime and 1 of rock phosphate

hybrids...shallow rooted...

Most of the rhododendrons we grow are hybrids. Hybrids result when two or more of the plants found growing in the "wild"...the species...have been combined by cross-pollination. Most of the species that have been used to make these popular hybrids come from climates that have relatively dry winters and high summer rainfall. In the Victoria area, we have the reverse. One of the consequences of our persistent winter rainfall is the nutrients that are on the surface of the soil get leached downwards quite quickly.

Rhododendrons, which are very shallow-rooted, can in fact be starved in our winter because all the goodness goes past them before they can catch their fair share. The roots can't supply the nourishment, then the plant will draw from its stored reserves...its rainy-day account...leaving less for production of flowers and foliage.

Norm's fertilizer regime...

The regime I follow is to feed sparingly with a chemical fertilizer (10-8-06 with all the minor elements)...five times a year.

Start in November and feed every two months with the last feed on Canada Day (July 1st)...rhododendrons are not gross feeders...but they do like three meals a day...light ones in the winter, heavier ones in the spring.

it's your choice from some 23,000...

Choosing the right variety for the right spot is important. There are now more than 23,000 registered hybrids. This is a daunting number...but...from its very size, you can be sure that the right plant for your particular location can be found.

Some need almost no direct sun,
some need full sun,
some will grow to be trees,
and
some will never be more than 2 cm high,
some will bloom in December,
some will bloom as late as August,
some are deciduous,
most are evergreen.

Colors range through the entire spectrum…except for the pure gentian blue. Even that is now a possibility with our increased understanding of genetics.

most portable of all...

One of the convenient characteristics of rhododendrons is that because they are shallow-rooted, they are very portable. For gardeners who would really like their plants to come with wheels so they can move things around until their concept of horticultural artistic perfection is reached, rhododendrons come quite close to being ideal. They can be moved at any time of the year. The huge majority are planted in the spring and they do well. The very best time, however, for gardeners in the Victoria area is the fall.

Norm, thanks again for giving readers around the world the very basics of having rhododendrons in their garden. Looks like we are really going to have to get busy with any planned planting...and to do it NOW.

 


Geraniums...winterover

It seems that nearly everyone loves geraniums...no matter if they are pink, white, red, or a wide range of variations. If the truth were known, all dream of wintering the plants over so they will have the same beautiful plant the following spring. The North Island editor has a few suggestions. They are in order at this time of the year...fall...when we are thinking about tidying up our "riverbanks" to get ready for winter. Three methods are suggested:

Method #1 At the end of the summer, gently pull your plants from the soil and brush away any dirt that clings to the roots. Hang the entire geranium, flowers, leaves...and all...upside down in a cellar or other damp place where the temperature stays between 40 and 50 F all winter.

If the location seems too damp, wrap the plants loosely in newspaper before you hang them to reduce the chance of molding and rotting. The plants will look dead, but don't water them. At planting time in the spring, strip off the flowers and leaves and repot them. Some people soak them for several hours before replanting...but if you water them well, it isn't necessary.

Method #2 If you lack the windowsill space necessary to keep your geraniums growing, you can dig up your garden plants and put the same ones back outdoor come spring...just pack those plants in a box!

In the fall, dig up the plants from the garden...before frost hits...and gently shake off most of the excess soil from the roots...leaving some around the root ball. If you want, you can prune (pinch) back the top of the plants...but I get equally good results with un-pruned plants. Then wrap each plant individually in newspaper, set the wrapped plants inside a cardboard box and store the box(es) in a cool dry place for the winter.

In early spring, take the dormant geraniums out of the box, pot them up, place them in a cool bright window and water lightly. They will start growing within a few weeks. (If you live in a cold climate, be sure to harden the plants off for a couple of weeks before you plant them outdoors.)

Method #3 Take up geraniums (pelargonium). Cut tops back to five to six inches. Pot each individual plant in a sandy soil mix in a 5-in. pot, and keep them in a bright window over winter.

Water sparingly in the "off-season", and do not fertilize...at all...so plants will stay small and bushy. If they grow too tall, just cut them back a bit.

In spring when weather has warmed, plants will be double in size, return them to their summer homes. Fertilize with bone meal...and water with balanced liquid fertilizer every two days or so until they are established.

 

Older, fallen, gangly, weak rhododendrons...

Kathy Collier of the Portland Chapter is preparing us for the fall and winter months ahead. She is thinking specifically about some of our older, fallen, gangly-looking rhodos around our gardens. Unlike a lot of other plants, however, rhodos can be totally rehabilitated when they get to this condition. She indicates three major conditions...then adds...unfortunately these techniques will not work for humans!

Thin and Spindly...Conditions, such as the amount of light, nutrients, and drainage, may have gradually changed over the years.

Strong winds and damage from ice storms can badly damage plants...and you might not notice it...until branches begin to die-off. Heavy limbs, or trees, hitting rhodos can shatter a plant...but it may not kill it. Rot and disease, however, can creep into a wound and eventually kill plant. Typically, by the time you have discovered that a plant has stem dieback...it is already too late to save it.

'Couch potato' look...the plan may be overgrown and need a good haircut. This is not the best time to prune...but it is possible to prune out 'water spouts' or other obnoxious growth where you won't miss the blooms next year.

Now...what to do:

Check the soil...moles and gophers can cause dry pockets which are deadly to many plants. You may also want to check the pH, and how crumbly the soil might be...it may be time to add compost blended with some bark around the base of the plant...avoid piling up materials next to the stem.

Evaluate the light...a little judicious pruning of the overhead tree branches might be just the ticket! This can be done in stages over a couple of weeks during the hot months to minimize the chance of sunburn and rapid soil dehydration.

Prune out the deadwood...this can be done at any time of the year...and is a good activity to do when checking the soil. Rhododendrons and azaleas bloom on the prior year's wood...that is...wood that is alive. Dead wood does not generate blooms which is why most pruning is done after blooming.

Deadhead the plant to prevent seed production...which wastes energy...and tidy up the plant. Consider pinching out single terminal growth buds to create a more bushy plant.

Cut back the limb damage...to the nearest sound branch or trunk. In severe cases, this may mean cutting the plant back to the soil level and babying it for awhile. If the plant was healthy and well established, it will most likely re-sprout from the roots. It may, however, take a couple of years to recover and begin blooming again.

What no one has probably ever told you...
you can find in Ed Reiley's book, Success with Rhododendrons and Azaleas, Timber Press, answers to your questions.

Leave a 1/8-in. stub against the trunk when making cuts close to the trunk or large stems. Not only will this heal over more quickly than a larger cut flush with the trunk...but will also minimize tissue death in the trunk.

Plants cannot tolerate severe pruning at close intervals. The result could be more than just the loss of blooms. A weak plant may not heal as fast...and may be more prone to disease.

Some plants grow inside limbs that can be shaded out and become weak. These stems can be removed to avoid this problem, increase the amount of air circulation, and keep stems from crossing over each other.

Not all rhodos and azaleas are the same. You have probably noticed that some plants send up long, straight 'water shoots' These adventitious buds will break easily and are often liberally scattered along the stems. These stems are frequently found on azaleas and lepidote rhododendrons...those with scales...and can be cut back to any point.

Elepidote rhododendrons...those without scales...however, do not develop these stems or new shoots as readily. Plants should be vigorous and in good health before pruning.

Some cultivars are more sensitive to pruning as well. Some will regenerate quickly with multiple growths, while others may take years to regenerate...if ever, gradually over a few years and pruning above areas that have some small shoots already can help minimize the trauma.

Root pruning may be useful when moving larger plants. Recommends pruning a year before the move to produce vigorous root branching.

Kathy and Ed, thanks so much for your study and research...then sharing so we can improve the appearance of our gardens and bring health of our beloved rhodos.

 

A beloved American poet friend gives some advice...

Whatever a man's age,
he can reduce it several years
by putting a bright-colored flower
in his buttonhole.
-- Mark Twain
 

 

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