The English method for growing “plunge-pit” mums combines the advantages of both outdoor growing and greenhouse culture.
I have grown prize mums with this system, with certain modifications, for all varieties which bloom in November and December.
Chrysanthemums For Exhibition
English gardeners who have greenhouses grow chrysanthemums for an exhibition using a 9- to 10- month growing schedule.
Cuttings are taken during January and February and pinched several times before potting in their final flowering pots, which often are as large as 10” inches in diameter.
The plants receive their final potting in May or early June and are then plunged to the pot rim out-of-doors in a protected spot in full sunlight.
Of course, each plant requires a stake, and additional feeding is provided by adding fertilizer to each pot during the growing season.
Bud Selection
Apparently, each English grower has his own preference for bud selection.
Most articles mention the selection of either crown or terminal buds for each variety, but no logical system appears to be followed.
The floral display seems to receive the most meticulous care, for the English articles stress the staging tiers in the greenhouse.
Upon which the mums are arranged for exhibition, and the care to be followed in placing and watering the pots.
Natural Progression of Cuttings
Using this English system, I decided to postpone taking cuttings until March and April so that a natural progression from cutting bench to cool house to the cold frame.
Finally, the plunge pit would not tie up too much greenhouse space when the benches were overflowing.
This had the advantage of preventing the premature formation of flower buds in April or May on varieties such as Indianapolis Pink and its white, bronze, and yellow relatives.
Also, such tall growing varieties as Tuxedo do not reach 8 feet when the date of taking cuttings is delayed.
English Methods for Blooming
If this departure from the English method reduced the size of the blooms, I would not hesitate to abandon it.
I have had success in growing prize-winning blooms, and they seem to be equal in every respect to those from earlier cuttings.
Main Plunge Pit
For my main plunge pit, I dug an area 6’ by 18’ feet to a depth of 10” inches. Around this, I laid one course of 4”-inch wide cinder blocks on a 4”-inch concrete footing.
The pit was then filled with clean builder’s sand within 3″ inches of the top. Next, a 5-foot half-inch galvanized pipe was embedded in concrete at each corner.
So, by connecting a horizontal piece of pipe to the corner pieces across each end, solid support was given to the wires run lengthwise at the proper height for fastening the individual galvanized wire plant stakes.
Plants in Each Row For Exhibition
When the pots were placed in the pit, the sand level rose to within an inch of the top by June 15.
When the last pot was in place, there were three rows containing 22 plants in each exhibition row, such as:
- Spider
- Quill
- Anemone
- Commercial Varieties
It was grown to a single stern and two rows, containing 12 plants in each row of pompons, grown to terminal sprays.
Cuttings from Stock Plants
In March, I start taking cuttings from stock plants carried over the wittier in the cool greenhouse.
Normally, I take the cuttings as they de-veiny, except in the few cases where the plants do better from late cuttings.
I dip the cuttings in hormone powder and place them in rows in the greenhouse cutting bench in clean builder’s sand which is kept uniformly moist by sub-irrigation.
When a mass of inch-long roots has formed in about two weeks, I transfer the plants to 2-inch pots using a mixture of topsoil and compost with no fertilizer or manure added.
Newly Potted Plants
The newly potted plants are placed on a greenhouse bench containing a 2”-inch layer of sand kept damp to prevent any wilting during the next three-week critical period the plants remain in the greenhouse.
At the end of this period, the plants are transferred to the cool greenhouse and then several weeks later to a cold frame.
When the roots emerge from the drainage hole in the bottom of the pots, the plants are shifted to 7-inch pots using a rich soil mixture.
Then, starting about the middle of May, the plants receive their final shift into 7”-inch pots, which are placed in the plunge pit.
Final Potting
For this final potting, I use rich soil containing about a quarter of well-rotted manure and about one 4”-inch potful of superphosphate for each bushel of soil.
When the pit is filled, a 6-foot galvanized plant stake is placed in the center of each pot containing a plant grown to a single stem.
Fastening the Stakes
The stakes are fastened to the wires that run the pit length using a paper-covered “plant.”
As the plants grow up the stakes, the same type of fastener is used to keep the plants growing straight.
Three-foot stakes are used for the pompons with no wire support, and the individual branches are trained by using string fastened to the stake.
Systemic Poison for Stopping Insects
I believe in stopping insects before they do any damage, so I use a systemic poison, sodium selenate (P-40), mixed with 5-10-5 fertilizer to combine feeding with insect control.
I mix 1/4 part (P-40) to part 5-10-5 fertilizer and put a teaspoonful in each pot during- the first week in July and then again the first week in August.
A Layer of Peat Moss
This past year I added a 2”-inch layer of peat moss on the top of each pot and was very pleased with its effect on moisture control and its smothering effect on weeds.
I also make several more feedings of straight fertilizer before the buds show color.
Soft Pinching Before Blooming
To control the bud selected for flowering, I use the system developed by Cecil Delworth, which involves a soft pinch (top ½” inch of terminal growth) about 90 to 100 days before blooming.
“Chrysanthemums For Pleasure”
This method is well illustrated in the book by Dr. and Mrs. Ernest L. Scott entitled “Chrysanthemums For Pleasure.”
This pinch, which eliminates the broken bud, produces several lateral growths, and to grow one large bloom to each plant, only the strongest shoot is allowed to develop.
All the rest must be cut off close to the central stem with a sharp knife. As the plants grow taller, many additional shoots develop along the stem, and their removal is necessary.
Usually, this soft growth can be pinched off using the thumbnail, making a good after-dinner task during early September evenings.
During Terminal Growth
In September or early October, the terminal growth will produce a central flower bud surrounded by small buds.
As soon as the smaller buds are large enough to remove, they should be rolled away from the central bud using the thumb and index finger or else a sharp thin knife.
A little experience makes this an easy task. The remaining bud is either a crown or terminal bud, as determined by the pinching system.
Moving the Plants To A Cool House
In mid-October, I begin to move the plants into a section of the cool house, and from there, as the plants come into bloom, they are placed in the center bench of the greenhouse.
The natural difference in different varieties’ heights makes building special staging unnecessary.
Several rows of pompons with a row of cascade mums, or a few pots of hanging petunias at the edge of the bench, hide the long stems of the single-stem varieties.
The center bench has a layer of several inches of sand upon which the rest of the pot is.
Additional Watering
By keeping this moist, very little additional watering is required during the display season, which, by rearranging and adding new plants, lasts from early November into January.
The preceding may sound like a lot of work, but it is a leisure-time job for me, and I still have plenty of spare time for growing other greenhouse crops and several hundred outdoor mums.
The important thing is to plan ahead so that there is always a little work to be done when time is available and no sudden pile-up of work.
It is difficult to prepare any list of varieties which can be described as the best because individual tastes vary.
Growing Varieties In Two Plunge Pits
However, I like to have available for display all mum types, including exhibition, commercial, anemone, quill, spider, and pompons in many color combinations.
So I grow only a few of each variety in the two plunge pits I have. Like most gardeners, I hate to discard any plants that have been faithful through the years. and yet, each year, I see several new varieties I have to make room for.
Records Of Exhibition Varieties
Accurate records are important to aid in making each year’s plans, so I have devised a system of records that shows the varieties I grow using the plunge pit method, the date they are pinched, and the date they bloom.
As you will see, most of the varieties listed bloom after Nov 1, which is the latest date I can expect to avoid frost damage in the open garden.
Those varieties on the list which bloom in October are those which do not winter over very well in the open garden.
Next Year’s Garden Cuttings
By growing one or two stock plants by the plunge pit method, I am sure of having cuttings for next year’s garden.
All commercial and exhibition varieties should be grown single stems for best results; most spider, quill, or anemone varieties will do well, either grown single stems or as multi-flowered bushes.
Pompons: Well-Branched Plants
The pompons usually do best to grow as well-branched plants with good terminal sprays produced by the timed-pinch method.
Although some pompons can be grown disbudded with a single flower to a stem and from one to four or five stems per plant.
Bloom of Fair Maid and Rose Mandel
The blooms will resemble a baseball in size and shape if grown from one flower to a plant. Both Fair maid and Rose Mandel are ideal for this method of culture.
This list represents quite a few years of trial and selection. I am sure you would be pleased to grow any one of the varieties.
If you are not already a victim, I am sure you could easily succumb to that delightful disease I call “Chrysanthemania.”
44659 by Cornelius Ackerson