Meets second Tuesday of the month at Rose City Park
United Methodist Church, 5830 N.E. Alameda
Editor: Mike Riordan (503) 256-0425
Next meeting Tuesday, June 10th, 2008 @ 7:30 PM


Treasurer Larry Sawyer reports net income for the Master
Gardeners’ Sale at $1990.  Mega thanks to all the volunteers that
helped with all aspects of our society fundraisers. Our May
plant auction netted $341.50 and the May close-out sale table
$298.50.  Our overall sales income was down slightly over last
year.  We may want to blame it on the economy or the rain the
weekend of the Master Gardeners’ Sale, but the good news is
we have the funds to put on our show and carry the society into
next year.


Cookie host for June is MaryAnn Hoopes.


Our program for June will feature Vicky Molina from the Rain or
Shine garden store in Portland.  Vicky will give a presentation
on insect management.  She will also have some books
available for sale.


With profound sadness we note the passing of Gordon
Jackman’s mother, Donna Jackman, on Saturday, May 24th.  
Our sincerest condolences to Gordon and his sister and the
Jackman family.

By Max Ollieu

June is really a busy month for me in my dahlia garden.  Since
my choice is to start my tubers in one gallon plastic pots, they
need to be transplanted to my garden the latter part of May as
well as much of June.  Even cuttings I have been able to obtain
have been repotted and need transplanting as well.  So, much
of the month is spent digging holes and transplanting the best
of the new starts.  This year, I will be transplanting about 80% of
my new crop.  The rest will go to friends or be discarded.
I begin my monthly applications of Messenger June first and
plan to continue those applications through September first.  In
my opinion, Messenger helps provide better and stronger tuber
crops, resistance to the effects of disease organisms such as
powdery mildew and tuber rot, and enhances above ground
plant health and size.  Application of fertilizer in June is a
heaping tablespoon of slow release nitrogen in each hole since
my phosphorus and potassium levels are already adequate for
my garden.  I also start my applications of insecticide in June
and plan to alternate between Orthene and Wisdom (Bifenthrin)
which is a cheaper product than Talstar, also a Bifenthrin
product.  Of course, my worst pest is the slug, so heavy
applications of slug bait are made as soon as plants are placed
in the garden as well as patrols morning and evening to
manually control any slugs found approaching the garden.

The plants also need to be groomed in terms of topping and
bottoming (my term).  Topping for me means removing the
terminal buds on the main stem to encourage growth of
laterals.  Bottoming to me means removal of the laterals lowest
to the ground to allow for air circulation as well as room for the
mulch to be added in July.   Mainly though, I need to get the
right number of laterals for the particular dahlia variety being
grown.  Lateral management is extremely important for those of
us trying to grow our best show dahlias and I work hard to keep
to the number I have selected for each variety essentially to the
last show.

I grow my mignon singles and peony type dahlias in large
containers.  Since both types are small, it’s nice to have them
elevated for deadheading.  Also, they don’t have to compete
with larger dahlias and grass.  Fortunately, they seem to do just
fine in large containers.

Do try to manage healthy plant growth by allowing only one
sprout to grow from each tuber.  If multiple sprouts are allowed
to grow, they tend to compete with each other resulting in
smaller flowers and generally weaker growth. Don’t remove the
unwanted sprouts by pulling on them.  I did this at one time,
until I managed to break the neck of the only tuber of a new and
expensive variety.  Pinching or cutting works fine.  Pulling, a
definite no-no.
Do water green plants to keep them growing vigorously. A
liquid fertilizer at half strength administered weekly will also
keep them growing strong.  During periods of hot weather, this
could make all the difference in healthy plants vs. throwing
them into a stalled, shocked state where they are apt to express
viral symptoms.  If you have tubers and green plants growing
together hand watering the green plants is the preferred
option.  If during the middle of June the ground begins to dry
out a bit, one can start overhead watering.  Using an oscillating
sprinkler, the gardener can simulate a refreshing spring shower.
Morning showers as opposed to evening showers would be
less conducive to powdery mildew. When the plants reach
about a foot high, I usually put out the drip tape and begin
watering in the normal manner.  At this point all overhead
watering is discontinued.

Every year it seems that some varieties begin looking virused
that have never shown symptoms previously. Tell-tale oak leaf
or mosaic patterns in lighter yellow on the foliage or yellowing
along the foliage mid-rib may indicate stock that should be
culled.  Some yellow spotting of the leaves can be caused by
insect damage (e.g., thrips) and is not to be confused with
disease.  If you look on the undersides of the leaves you can
see where the insects entered to cause their damage.  If you are
not sure if a plant is diseased, you might want to ask the
opinion of a more experienced grower or bring a leaf sample to
our meeting.

Dahlia smut is a curable fungus disease that at first symptom
looks like dahlia ring spot virus.  If left unchecked, the spots
will rot all the way through the foliage giving a “shot hole”
appearance.   The smut is likely to occur in the same areas of
the garden each season as the fungus winters over in the soil. It
seems to be most prevalent in June in our area.  Daconil is an
effective fungicide against dahlia smut available to the home

The rotting mother tuber phenomenon usually happens this
month.  You may have a strong healthy plant that suddenly,
inexplicably begins to wilt.  Usually, this means the mother
tuber is decomposing.  The plant will attempt to survive by
growing new side roots, but this takes a little time.  To help
Mother Nature along, try shading the plant on the South and
West sides with a piece of cardboard about a foot square held
in place by three stakes per side.

Replanting is a seldom discussed subject.  But nothing ever
works out perfectly. And some plants don’t grow and others
need to be culled because they are diseased.  If the dahlia
grower has a few extra green plants, they come in handy for
this purpose.  A few extra tubers growing individually in pots
for this specific purpose work out equally well.  Having extra
stock for the express purpose of replanting also makes one
more apt to cull the plants you know deep down you need to


Cultivation and the manner in which it is done spell the
difference between success and failure in growing dahlias.  
Cultivation is placed ahead of watering as with proper
preparation and cultivation of the soil, moisture can be
conserved but watering without cultivation is worse than no
watering at all.  There is no truer adage than “the hoe is
mightier than the hose”.  Editor’s note:
A garden rake works even better than a hoe to cultivate and
loosen the soil.   The soil is raked around the plants and the
paths themselves between the rows are also raked.

Cultivation should be started as soon as the shoots are far
enough out of the ground to mark the rows.  The object is three
fold, to break the crust and conserve moisture, to allow aeration
of the soil and to destroy the weeds which take food and
moisture from the plants.  Cultivation should be shallow until
the plants are up a few inches after which it should be worked
several inches deep until the plants are a couple of feet high or
until the buds start to show.  Cultivation should always be
shallow close to the plants to avoid injury to the feeder roots.  
By the time the buds start to show the fine feeder roots will fill
most of the space between the rows and deep cultivation
should cease.  From then on cultivation should only be deep
enough to keep a dust mulch on top.  Many growers make it a
practice to always float the ground after cultivating as it helps
to prevent evaporation of the moisture.  A crust should never be
allowed to form as this will permit the soil to dry out in a very
short time.  The ground should be stirred at least once every
two weeks and should always be worked as soon after a rain as
the top surface dries out sufficiently.  The hoe is the implement
most used in the small garden for cultivation and is always
needed to remove weeds form around the plants in any
planting.  After the plants get well started, a rake may be
substituted for the hoe for close work as it is not so apt to
injure the fine roots.

From Practical Dahlia Culture published by the Portland Dahlia
Society in 1946.


Thanks to all who participated in the member’s classification
survey at our last meeting.  An overwhelming majority of
members approve of the new four digit system classification
system and the expansion of color and/or form classes this
change will allow.

Thanks to the efforts of Max Ollieu, the Portland Dahlia Society
has entered into a mutually cooperative arrangement (sister-to-
sister) relationship with the National Dahlia Society of Victoria,
Melbourne, Australia.  This relationship should foster the
exchange of cultural information, medals, e-bulletins and the
trading of dahlia varieties.
June 2008