Propagating and Storing Chrysanthemums
that have been propagated with care and grown on well should produce good quality blooms that will make a fine display in the garden or greenhouse. Here we detail propagation procedures and consider the cultivation of late-flowering types.
Stock selection ofis carried out by retaining for propagation the plants that have produced the best blooms in the previous season. Cuttings for propagation are taken from a ‘stool’ — the root of an old plant with a portion of the old stem and surrounding young shoots — that has been lifted and stored at the end of the growing season.
How to Propagate
Both early- and late-flowering chrysanthemums are propagated fromof basal shoots taken from stools that have been stored in a cold frame.
Lifting and storing stools
Leave the stools of the early-flowering types ofin the garden until the beginning of early winter (November). This provides a period of time during which the temperature occasionally falls below 4.5°C (40°F) — a cooling period that is necessary before plants can produce flowers.
Cut the main stems down to 15cm (6 in), then lift the stools carefully with a fork and wash off the with water that has had a little disinfectant such as Jeyes fluid added, to remove any pests. Remove all the leaves and cut down all green growth. Box the stools up into clean containers to a level no deeper than the original soil mark, in J.I. No 1 or a mixture of equal parts of loam, peat and grit. Water the stools well in to settle. The . Make sure they are labelled correctly and try to keep to one cultivar per tray. Place these trays somewhere dry and frost-free, such as a cold frame, where there is plenty of light and air. Probably no more water will be needed until the trays go into the greenhouse in late winter (January). Keep an eye on them until then so that you can deal with any diseases such as mildew or botrytis that may appear; if they do, dust with flowers of sulphur or captan.
During early and mid winter (November and December) the late-flowering chrysanthemums will be coming into full bloom in the greenhouse. As they mature, mark the plants that produce the best blooms and use them for future propagation in the same way.
In late winter (January) start to propagate plants for the new season. The late-flowering types should come first, particularly the large exhibition cultivars and those that require early stopping.
Prepare a rooting compost of J.I. No 1 or a mixture of equal parts of peat, loam and coarse grit, or any soilless compost. Water the stools well the day before you wish to take the cuttings, so that they have time to plump up. Depending on the number to be rooted, insert about six cuttings round the edge of an 8cm (3 in) pot. If you use a standard seed-tray, the compost should be about 5cm (2 in) deep. Firm it with a board, then sprinkle a layer of sharp sand on the surface, and space cuttings 4-5cm (1-1/2 – 2 in) apart each way.
Snap off a new basal shoot from the stool, just below a leaf joint, to form a cutting about 4-5cm (1-1/2 – 2 in) long. It is optional whether you remove the two bottom leaves as the cuttings will root well either way. Dip the bottom 13mm (1/2 in) of the stem into a hormone rooting powder, and make a hole 20mm (3/4 in) deep in the compost with a dibber the size of an ordinary pencil. Place the cutting in it and firm gently right up to the stem. Some of the sand sprinkled onto the surface of the compost will fall to the bottom of the hole, creating drainage that helps to prevent decay. Water the cuttings well in using a fine rose.
Keep the cuttings in the greenhouse until they have rooted. The time taken for rooting will depend on the conditions provided. In a propagator with a bottom heat of about 16°C (61°F) and an air temperature above 4.5-7°C (40-45°F) they should root in about two weeks, but on an open bench with a general temperature of 10°C (50°F) they will take a week or so longer. The cuttings can be rooted without heat when the risk of frost is over, but they take longer and the delay also affects the timing of blooms.
You can continue propagating until mid spring (early March); the late-flowering varieties should root during late winter and early spring, and the early-flowering during early and mid spring.
As soon as cuttings of both early- and late-flowering chrysanthemums have rooted, remove them from the heat to a cold frame. They need slow and steady growth in a cool place to produce short, sturdy plants with big root systems. Some growersof early-flowering chrysanthemums directly from the rooting tray into a 10 -15cm (4-6 in) deep layer of compost on top of a 15cm (6 in) bed of weathered clinker or ashes. Others prefer 10cm (4 in) deep trays or a succession of pots up to 13 -15cm (5-6 in). All these methods have proved satisfactory, so each grower should adopt the system that will suit the facilities available to him or her.
Late-flowering plants, however, must be transferred from their rooting quarters into a succession of pots, starting with an 8cm (3 in) pot and moving on as the root system develops to a final pot size of 20, 23 or 25cm (8, 9 or 10 in). Grown in this way, they can easily be transferred back from the open garden into the greenhouse towards the end of mid autumn (September), so that they will come into flower during early and mid winter (November and December).
When you move the rooted cuttings into the cold frame, ensure that they have as much light and air as possible. Leave the frame lights off whenever the weather permits, and when they are on keep them raised a little at all times, unless there is a risk of frost. During early spring (February), frost usually occurs at night, so cover the frame lights with sacks or pieces of old carpet. Water sparingly — just enough to keep the plants going. A strong root-system will develop from plants that have to forage a little for moisture. When the plants are settled in the frame, spray with a good insecticide such as malathion or a systemic insecticide containing gamma HCH (BHC) and menazon, as a control against pest attack — leaf-miner flies and aphides become active as the weather warms up during spring. During late spring (April), give the plants more air; by the end of the month the lights can be removed from the frames permanently. Replace them temporarily if a heavy rainstorm threatens.
In mid spring (March), the young plants that have been grown in 8cm (3 in) pots must be moved into larger pots to accommodate the developing root system. A compost containing a stronger mixture of fertilizer is necessary — J.I. No 2 is most suitable, or you can use an equivalent soilless compost. Before potting, decide on the type of compost you intend to use for the final potting. If you choose a soilless mixture, then the second potting should consist of similar material.
Use a 13cm (5 in) pot for the second potting, then return the plants to the cold frame, ensuring that there is a space of 5-8cm (2-3 in) between each pot to allow for leaf development. Leave the frame lights off at all times unless heavy rain, hailstorms or frost threaten — all such hazards are possible in late spring (April). The chrysanthemum is not a tender plant, and it would survive the hazards referred to, but the growing point could be damaged and the timing of growth and flower development affected.
The final potting is the most important of all. The plant will remain in this pot from early or mid summer (mid May or early June) until it flowers in mid winter (November), or even later in some cases. You will need a selection of 20-25cm (8-10 in) pots because some plants make more vigorous growth than others and therefore require more space. J.I. No 3 is suitable for most cultivars, but if you are using a soilless compost, follow the recommendations for use given by the manufacturer.
Put some crocks or pebbles at the bottom of the pot to provide drainage, then place a 2-3cm (1 in) layer of peat on top. Partly fill the remainder of the pot with compost and firm gently with a rammer. Finally, put in a handful of loose compost, on which you can rest the plant taken from the 13cm (5 in) pot. Place the plant in the pot, ensuring that you have left about 5cm (2 in) of space down from the rim for future top dressing. Fill in around the plant and firm well, using the rammer. Insert a cane on each side of the plant and secure it with soft string. Stand the pots close together when you have completed potting so that moisture is conserved. If possible, withhold water for 10-14 days after potting, to encourage the roots to move into the new compost. An overhead spray in the evening should prevent undue flagging.
Preparing a standing-out ground
Prepare a level site, in full sun if possible, for the late-flowering chrysanthemums to stand throughout the summer. The aim is to give each plant as much room as possible. Stand them in rows, preferably on an ash base; each pot should also stand on a slate or tile to keep out worms.
Drive strong posts into the ground at the end of each row, and stretch wires between them at 45 and 105cm (18 in and 3-1/2 ft) high. Fasten the wires to the canes, to keep the plants from being blown over. This advice may sound unnecessary on a quiet day in midsummer, when the plants are only 75cm (2-1/2 ft) high, but it is quite another matter in early autumn (August) when they are 1.5m (5 ft) or more tall.
Watering procedure is similar to that recommended for the early-flowering varieties (Week 88). An overhead spray on warm evenings usually suffices, but during dry spells water more heavily, giving a really good soaking. With pot-grown plants, watering should generally be more frequent than with the early varieties that are planted in the ground. Because of this extra watering, a certain amount of food is leached through the pot. About six weeks after the final potting, therefore, it is necessary to feed the plants. Dry and liquid fertilizers both give good results, as does a mixture of both. If you use dry fertilizers, give a pinch every other day. With liquid fertilizers, better results can frequently be obtained by applying little and often rather than a full dose every ten days, so dilute the feed to a quarter strength and use it at alternate waterings.
In late summer (the end of July), roots will appear on the surface of the compost. When this occurs, apply about 13mm (1/2in) of top dressing made up of the final potting compost — either soil-based or soilless — that you used before. A further top dressing will be necessary about three weeks later.
As with the early-flowering varieties, decide how many blooms you want to grow and restrict the laterals accordingly.
If you are growing for show purposes, restrict them as follows: large and medium exhibition — one or two laterals; exhibition incurved and decoratives — three laterals; large singles — four or five; and medium singles — five or six. Apart from the large exhibition type, these will all carry a larger crop of smaller blooms when being grown for cut flower uses.
Securing the buds and housing
At the beginning of early autumn (August), the first buds will start to appear on late-flowering chrysanthemums — the large exhibition type first. If possible, these should be comfortably secured towards the end of early autumn (by the third week of August). Buds on the incurved and decorative types will appear from early to mid autumn (the end of August to September). Once the buds are secured and growing well, remove any surplus laterals, always selecting those with the weakest bud. Continue feeding on alternate days until the calyx breaks and the buds begin to show colour. Then gradually reduce the feed over the next few weeks.
Prepare your greenhouse for late-flowering chrysanthemums by washing down the glass and framework and fumigating inside to clear away any pests.
As soon as the buds show colour, and before the frost comes, remove all dead leaves andaround the plants, wash the outside of the pots, and spray over and under the leaves with an insecticide such as gamma HCH (BHC) and menazon to kill any pests, and a fungicide such as benomyl to rid the plants of any disease. Then bring the plants into the greenhouse and position them in their winter stations. Leave doors and ventilators fully open for as long as possible to enable the plants to become acclimatized to the change of environment.
After bringing in all the plants it is advisable to fumigate the greenhouse occasionally — this should help to keep your chrysanthemums free from. Always keep a buoyant atmosphere in the greenhouse. High temperatures are not necessary — just enough heat to keep the air moving and to maintain a temperature of 10°C (50°F) is all that is required. A fan-heater is most suitable and will provide both warmth and air movement. Your chrysanthemums should then bloom well throughout the dreary months of early and mid winter (November and December).