Posted on

The Most Common Problems for Ailing Rhododendrons

It is a privilege to be able to work with so many of my customers when they are having issues with their rhododendrons.  I wish I could just stop by your yard and have a conversation, but for most of the time we are limited to emails when there are sometimes hours or days that go by between the time we get to converse.  I wanted to share with you an article that was published by the American Rhododendron Society in 1994 by Jan D. Kelley.  I have shared this with many customers already and I hope that this article can help in two different ways.

This article my help preventing some of the issues that can occur later.  I enclose planting instructions with every plant we sell, but it does not cover the care of the plant.  Here are some Very, Very basic steps as to what to avoid. 

If your plant is struggling, you might find something in this article that may aid you in changing the environment for your plant.  I agree with the author that the great majority of rhododendrons that I see struggle have been planted in an environment that does not allow the soil to drain away excess water.  I hope that article may help in a few questions you may have.  I am always available via email for all questions!  Jim

https://www.rhododendron.org/v48n2p85.htm

 Top Causes of Death in Rhododendrons

Jan D. Kelley
Drain, Oregon

Our hopes soar with the coming of spring as we anticipate another excellent growing season for our rhododendrons with their exquisite flowers.  As we ponder the fantastic new hybrids in the pages of the several catalogs that we receive our vision of being successful gardeners bursts forth.  However, as you reflect upon last year’s plant losses a ray of doubt creeps into your consciousness, and the nagging question emerges: “Why did that plant die?”

For the past 15 years I have enjoyed raising rhododendrons.  During that period of time I believe that I have killed rhododendrons in every conceivable way.  In the remainder of this brief article I would like to identify some of the various ways that rhododendrons succumb in our yards and gardens.  My experience indicates that most rhododendrons die from about seven causes.

To begin with, excessive water kills about 75 percent of all rhododendrons purchased.  Rhododendrons are fibrous, shallow rooted plants that need good drainage to perform well.  Historically, gardeners have been told to dig a hole twice as wide and twice as deep as the root ball.  After the hole is completed put the plant in the hole and back-fill it with a mixture of peat, soil and other amendments. Many rhododendrons die from this guidance.  The result of digging the hole and planting the rhododendron in it is nothing more than putting the plant in a bathtub that holds excessive water.  The continual presence of water around the root ball prevents the roots from taking in vital oxygen as well as serving as an excellent incubation chamber for fungus diseases.  It seems that most of the native soils around the country have an excessive amount of clay in them.  The presence of clay in the soil prevents good drainage, which is vital to the growth of the rhododendrons. Anyone who has ever been to the several locations around the world where rhododendrons originate knows that rhododendrons grow in shallow beds of highly organic matter.  The drainage is typically excellent.

Another cause of rhododendron death is lack of water.  Rhododendrons do not have taproots like trees: their roots grow very near the surface.  Therefore, they need frequent watering.  The acquisition of new plants in the spring requires regular watering.  During the first couple of years watering the plants at least twice a week is a must.  As the time goes by and the plants increase in size and root development, watering less frequently works well.  After about five or six years it is possible to water weekly or even bi-weekly.  Frequently sunburned leaves are the result of the lack of water.  For many varieties that have burned in the sun in the past, the cause was lack of water not too much sun.  Burned tips on this year’s new growth is typically indicative of lack of water as the plant withdraws water from the tips of the new foliage first.

Another cause of rhododendron death is the excessive application of fertilizer.  This is particularly true of applying fertilizer directly at the base of the trunk of the plant.  A good rule of thumb is to fertilize more frequently with smaller amounts, rather than one large dose.  This is especially true for small plants or newly transplanted plants.

A fourth reason for rhododendron death is planting too deep.  As indicated earlier, rhododendrons are shallow rooted plants.  Their roots grow just below the soil line.  If they are placed too deep in the ground, the soil that covers the roots serves to smother them.  I have found that planting too deep will basically stop the plant from growing.  Eventually this leads to the death of the plant.

Another reason that rhododendrons die is from cold winter temperatures.  Most rhododendron sources indicate the lowest temperature range in which rhododendrons can be successfully grown.  This hardiness rating is a guide not an absolute!  In general, the lowest temperature during the past five years is a good guide for making selections based on hardiness.  Years ago there were very few plants that were hardy in -25°F for the extreme climates.  Now we have over 100 varieties that will survive those winter temperatures.  Gardeners in the East should select hardy varieties in the beginning.  With time and experience less hardy varieties can be successfully tried.  A rhododendron rated hardy to 5°F, no matter how beautiful it is, planted in Green Bay, Wisconsin, will not survive.

As more and more home gardeners in the Southern and Midwestern states begin to grow rhododendrons, increased attention must be paid to the hot summer sun.  Most varieties exposed to unprotected all-day sun are doomed.  However, there are available rhododendron varieties that can stand direct sun.  In general rhododendrons in extreme climates benefit from filtered light and partial shade.  Planting in a southern exposure without any protection from the sun nearly guarantees plant death.

Finally, if you create the right conditions most rhododendrons will be subject to fungus diseases.  Typically we combine several fungus diseases into a general category of “die-back.”  The results of the disease are seen during the late spring when the plant is just beginning to grow and all of a sudden it drops dead.  It is also seen during the summer when a branch turns brown and dies.  Frequently the ailing plant will be lost.  These phytophthora-type diseases are generally the result of conditions created by the gardener, as it is believed that the disease spores are present in the soil all over the country.  Some of the ways that we promote these organisms is by planting the rhododendron too deep, thus providing a water culture for the development of the disease organisms.  Puddles of water that remain more than an hour after watering also harbor disease.  Watering in the late afternoon or evening encourages disease development.  Finally, failure to use fungicides during the late spring and summer encourages the development of fungus.

In conclusion, you are not alone if you have lost plants to any of the above mentioned causes of rhododendron death.  Most of the causes can be overcome with the intelligent selection of plants that are suited to your geographical area.  Finally, think about where and how you planted your rhododendrons and what you did to promote their death.

Posted on Leave a comment

Giving Branch Structure to Your First and Second Year Rhododendrons

Purchasing a smaller, younger Rhododendron has its advantages and comes with a few added responsibilities of the owner.  I would like to share with you some tips on creating a plant that will grow into a larger plant with added shape.

Most Rhododendrons will naturally grow to meet the minimal needs of the plant.  If left to grow out on their own, they tend to have fewer branches and usually favor a side that will have taller or wider branches.  When we have Rhododendrons in our groomed landscape, most owner want to have a shape that is more traditional and provides the most blooms for color.  If a shapely plant is desired, the owner of this plant needs to take a few steps in the first couple of years to ensure that the branching starts from the beginning.

We have been so pleased that many of our customers have selected first and second year plants.  For the most part, these sizes have not been available to the consumer because of the extra steps that need to take place to ensure a plant that meets the plant structure standards of most home gardeners.

Speaking in general for most rhododendrons, they will put on at least one new set of growth each year.  Most first year plants that we sell will arrive to you with at least two branches.  In order to achieve a shapely plant, you will want to encourage your plant to grow multiple sets of branches in the next growing season.  This is simply achieved by using a pair of scissors and pruning your plant about half way up the branch.  This pruning will encourage new branch growth below the cut.  There is a lot of variation in plants, but typically you should expect between 2 and 5 additional branches to form from this single cut.

In the second year of grow, we follow the same steps.  When a plant has started to develop larger branches during this second year, many times you can actually see the branch buds on them stems.  It is ideal to make you cut about ¼” above the bud to promote growth in that bud and in other buds on the same branch.  Ideal buds to trim above are buds that are pointing to the outside of the plant.

Timing is important when you are trimming branches.  New growth from your plants can take 6-8 weeks to “harden off” and make them less susceptible to freezing conditions.  If you are located in a place with longer growing periods, you may get two “flushes” of new growth in one season.  If you are happy with the shape and the number of branches that you plant has, trimming just as your plants are coming out of dormancy is ideal and may allow some of the new branching to produce flower buds.  Typically, flower buds set for the next year right after a plant blooms.  This fist “flush” of new growth when trimmed early can set flower buds.  If you are working on structure, you can trim growth on second year right out of dormancy plus possibly again when the stems are rigid or when you can see the stem buds. Make sure that you do not do any trimming with less than six to eight weeks before the first frost, or you may lose the new growth.

The first couple of years of growth are a great time to achieve balance in you plant.  If you are seeing one side of your plant that is heavier with branches than the other or if you are seeing branches that are much taller than others, removal of the branch or trimming the branch back to a stem bud that will bring it back to the shape of the plant is ideal to do in the first couple of years.

Purchasing First and Second year plants is really a lot of fun.  I am always amazed at how quickly the babies grow and become amazing looking plants.  There are volumes of literature written about the information above.  I encourage you to spend some time with a couple of books from the library or visit the web site of The American Rhododendron Society for great information.  Changes are, the questions that you might have, have been asked before and have been answered by people with great knowledge and experience.  As always, please feel free to email us at RhododendronsDirect.com.

Posted on Leave a comment

A Few Tips on Winterizing your Rhododendrons

I thought that I might also share some tips with you as to how best to prepare your plants for cold weather. These tips are mostly from The American Rhododendron Society(http://rhododendron.org/) who are a great source of information for rhododendron growers.IMG_2060

  • Hydration is important for the winter. If you have the ability for a good soaking in late fall and covering with mulch that will hold the moisture and insulate the ground around the root system as long as possible, your plants can use this moisture intake to help their systems during the freezing winter months.
  • Protection from drying winds. Planting I areas that are sheltered from winds are recommended. If you have plants that may have wind exposure, creating a wind break or wrapping in burlap can help protect them.
  • If you plants are in containers, move them to areas that are close to the house and/or onto the ground where they can use the warmth that is radiated by the heat of the house and ground.
  • A customer from Connecticut suggested spraying with a 5:1 dilution of Wilt-Pruf in November on a dry day above freezing. This will help in preventing wind damage.  He reminded me how difficult it can be to spread a trap or burlap on mature plants that can be 15 feet tall!  Thank you Bruce!  Here is a link to Wilt-Pruf on amazon.
Posted on Leave a comment

Reserve Your Plants for the Spring and still have Money for Presents under the Tree!

Don’t miss out on the best selection of plants we have now in the fall!  The plants listed are for sale to landscapers and retail nurseries across the country.  These businesses place their orders for the Fall for the Spring.  I want you to have the best selection possible, so now is the time to place your orders without having to spend your entire planting fund(or Christmas fund!).  Just place of deposit of 25% of the cost of the plants, plus shipping.  I will hold onto these plants for you until the Spring, billing you for the remaining balance in January, February and March. We will ship in the middle of April unless you let us know that you would like them at a different time.  It’s easy to do!  Follow these steps:

  1. Select the plants you want from the web site.
  2. Use Coupon Code “springblooms2016”
  3. The coupon will take 75% off the price of the plants. The remaining 25% and shipping will act as a deposit
  4. I will send you a bill via PayPal in January, February and March, requesting 25% of the total.
  5. I will ship your order around the middle of April or at your request.

If you change your mind along the way, all that you have paid will be completely refundable.  If you want to pay entirely at one time, that works too!  I also want you to know that we ship year round in case you want to get a few things in before winter.  There may be a week here or there that we will have a delay, but if your weather is suitable to receive a shipment, we will ship.Oudijk's Sensation3

Posted on Leave a comment

First Year Plants

We are very happy to offer our customers plants that are in their first year of life.  This is a very economical way of establishing variety while learning about the growth habits of their plants.  We offer two different types of first year plants, both being “clones” of the parent plants, ensuring the characteristics of the named plant.

Cuttings:  Cutting are usually taken in the fall and rooted over the winter in a warm and  humid climate. They are cut from parent plants trimmed, “wounded”, dipped in a rooting hormone, and placed in a sterile bed to root over the winter.  In the late spring, the result is the cutting taken from the parent plants with a root ball that ranges in size from a golf ball to a baseball with new growth emerging from the stem.

Tissue Culture:  Tissue culture or micro propagation is a popular method of producing large numbers of rhododendrons for commercial production.  Over simplified, it involves taking a small vegetative shoot section from the parent plant and putting it into a test tube.  Through the use of agars and auxins, absolute sanitation, proper temperature and lights, the vegetative shoot is induced to grow into multiple “seedling-like” growths with no roots. This tiny juvenile vegetative shoot is then rooted.  These plants tend to have a more minute shrub like look and will have slightly larger root balls.

From either method, you will have a healthy little plant that needs a bit more care than an established plants.

As in nature, new plants need extra protection from the elements.  If nature had produced these plants, they would be seedling growing under the protection of the parent plants.  Your plant will need to have protection also which includes filtered light, protection from wind and regular moisture.  They will also be susceptible to fungus and insect.

Below is the hand out we send with each order of first year plants.  The instructions are given to ensure that you have the most success with your plants, but please don’t get lost in the “must do this or must do that”.  Consider yourself the plant parent and protect your little plants for their first year and you will be amazed how quickly you will have a full size plant giving you enjoyment in your landscape!  Jim

 

Thank you for your purchase of first year plants. This is how most every rhododendron that is sold today starts! Please find below some growing tips and as always, please feel free to email or call if you have any questions.

PLANTING: Pot up or plant in a protected area. If using a pot, plant into 4” or one gallon. Use a loose, well-draining medium such as one containing some bark, compost, or perlite.

WATERING: Keep soil thoroughly wet but never soggy.

PROTECTION: Shelter from heat, frost, and wind for the first 6-12 months in a protected area such as a plastic covered hoop house. Keep it open and shaded in summer. Antidessicants such as Vaporgard or Wilt Pruf (available online via Amazon)can be used as protection from both heat and cold.
SHAPING: New growth is expected in 1-2 flushes the first summer. Pinching out the center bud will help the lateral buds develop thus producing a more bushy plant.

FERTILIZING: Use a liquid fertilizer 20-20-20 1T/gal. applied once every 7 to 10 days between April and August. Stop fertilizing in time to allow new growth to harden before first frost. Epsom salts, 1 T/gal., can be applied occasionally to add magnesium for better color.

WEEDING: Hand weeding is best because plants are shallow rooted. Preemergent herbicides are not recommended for these young plants.

DISEASE CONTROL: Root rot occurs in some varieties, especially in yellow flowered rhododendrons, when conditions are both hot and wet. In the Pacific Northwest this is in July and August. Well drained planting soil is essential. New biological products such as Rootshield (available via Amazon) or Actino-iron contain beneficial organisms that form protective colonies on the plant roots. These must be applied before problems are expected. Powdery mildew may be evident in some varieties and some climates. Use a systemic fungicide, such as one used for roses, so there is no need to spray leaf undersides.

PEST CONTROL: Weevils may be a problem. Watch for notching from the chewing beetles in the summer. Various insecticides may be used to control them. The grub stages of the weevil, which exists in the soil in fall, winter, and spring, does the most damage. It eats roots and underground stems and may completely girdle the plant and kill it.

 

 

Posted on Leave a comment

Phytophthora (Root Rot) in Rhododendrons

I have received many questions about rhododendrons that could be considered “tolerant” to Phytophthora from people who have lost plants during the long, warm wet summer. Digging into the archives, I found this article that was published in 1975 by the American Rhododendron Society by research done at The Ohio State University.  Though this article was published over 40 years about, many of the hybrids and the species rhododendrons that were available at the time are still available today.   I do not carry any on the very short list of resistant hybrids, however I do offer many that are on the second short list  of “moderately resistant” and “more tolerant”.  These are the plants that we currently offer that are on this list:

English Roseum( Purple, Hardy to -10, 7 Feet) http://oregonrhododendron.com/product/english-roseumaka-roseum-pink/

Mrs. C B Van Nes (Dark Pink, Hardy to 0, 5 Feet) Only limited number available in one gallons – please e-mail.

Rocket (Dark Pink, Hardy to 0, 5 feet) http://oregonrhododendron.com/product/rocket/

Roseum Elegans ( Pink, Hardy -10, 7 Feet) http://oregonrhododendron.com/product/roseum-elegans/

The Honourable Jean Marie de Montague (Red, Hardy to -10, 5 Feet) http://oregonrhododendron.com/product/the-honourable-jean-marie-de-montague/

Vulcan (Red, Hardy to -10, 5 Feet) http://oregonrhododendron.com/product/vulcan/

Vulcan’s Flame (Red, Hardy to -10, 5 Feet) http://oregonrhododendron.com/product/vulcans-flame/

I do not carry any of the species plants that are tolerant or moderately tolerant.  Due to the age of this article, there may have been new hybrids that have been introduced or further research done to determine tolerance.  Any new information I receive, I will post to this blog.  Thank you!  Jim

http://scholar.lib.vt.edu/ejournals/JARS/v29n1/v29n1-hoitink.htm