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 June 9th, 2009 @ 7:30 PM
Portland Dahlia Society Bulletin
Meets second Tuesday of the month at Rose City Park United Methodist Church, 5830 N.E. Alameda
Editor: Mike Riordan (503)256-0425 Contacts: Teresa Bergman firstname.lastname@example.org , Jeanette Benson (503) 649-
Next meeting Tuesday, June 9th, 2009 @ 7:30 PM
Thanks to all the volunteers who worked so hard on all of our tuber and plant sale fundraisers. Thanks to all the growers
who generously donated their tubers, plants, time, packaging, printing and labeling materials. Special thanks to Marge
Gitts and Swan Island Dahlias for use of their facilities for the two tuber packing work parties. Thanks also Marge for
the delicious lunches! We hope to have a financial report available at the meeting so we can see exactly where we stand.
Teresa Bergman is in the process of getting together a group order for Portland Dahlia Society T-Shirts. These are handy
to wear at shows so we can be identified with our club. They also are great to use during our fundraising functions to
identify us as working volunteers. More information will be available at the meeting.
The Portland Dahlia Society has purchased a very nice soil pH meter that can be borrowed by club members to check
the pH levels in their gardens. One of our members donated a very nice wooden box to hold it. We suggest that members
check their soil pH levels as most of the soils in our area tend to be on the acidic side. The meter can be used to check
numerous locations in the garden . A pH of 6.3-6.5 is a very good range for dahlias. If you want to borrow the meter,
please contact Teresa Bergman who will have it at our June meeting.
COOKIES FOR JUNE
Treat host for June is Jeanette Benson.
PROGRAM FOR JUNE
We will have a presentation on pest management in the garden
JUNE IN THE DAHLIA GARDEN
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.
Sometime this month growers generally pinch out, top out or ‘stop out’ their dahlia plants. This tends to create a bushier
plant with more blooms at their prime simultaneously. Most published materials suggest allowing 2 to 4 laterals to
develop for AA and A’s, 4 to 6 laterals for B’s, 6 to 8 laterals for BB’s and 8 or more for Miniatures. By directing the
plant’s energy through stopping, disbranching and disbudding, growers are rewarded with superior blooms in every
respect. As Max mentions in his article, you most likely won’t allow all laterals which form to continue growing. By way
of example, if you have a plant of Kenora Jubilee, with four sets of developed leaves, one has the possibility of eight
laterals developing after pinching out the growth tip. Far better to allow the top four laterals to develop and remove those
developing lower on the plant. By removing the lower laterals you have less chance of mildew and hard to reach insects
becoming an issue.
DOS AND DON’TS
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 gardener.
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 cull.
PEARLS FROM THE PAST
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.