Indoor Flowering Chrysanthemums – Indoor Flowering Plants
Unlike the early-flowering, the indoor chrysanthemum varieties produce their in the protection of a greenhouse. The amateur can adapt a conventional greenhouse to house his taller plants by removing some of the staging, and standing the pots on the floor. The shorter-growing types, such as the Charm chrysanthemums, can perhaps be accommodated on the staging. The ideal chrysanthemum house is the Dutch-light type which is fairly easy to construct at home once the lights have been purchased.
The temperature in the greenhouse does not need to be kept very high just high enough to prevent the atmosphere from becoming damp. If this happens thenwill become troublesome and botrytis (grey mould) attack will result in marked and spotted petals. I do not use any heat until it is absolutely necessary when the nights start getting fairly cold as I like to hold back the flowering so that I have blooms in December and well into January.
Electricity is, I consider, the most convenient form of heating. My house is heated by electricity thermostatically controlled, and I set the thermostat between 6° to 7° C. (43° to 45° F.). When the plants come into flower then I raise the temperature slightly to about 10° to 13° C. (50° to 55° F.), if cold foggy weather occurs. This keeps the atmosphere dry and there is no marking of the petals.
Heating with hot-water pipes can also be recommended. An oil lamp may be used but make sure the top ventilator of the house is left slightly open at all times to allow any fumes to escape, otherwise the blooms will be damaged.
Whenever the weather conditions permit, ventilation should be given. Free circulation of air is essential for keepingin check and the plants generally healthy. Side ventilation as well as top ventilation may be given when the plants are first moved indoors.
Bringing the Plants Inside
The indoor chrysanthemums must be brought into the house before frosts begin, otherwise the flower buds and tips of the shoots will be killed. I always get mine inside before the end of September. If any varieties were planted in the open ground for the summer these should be lifted and either planted in a greenhouse border or potted in suitably sized pots. They should be prepared for lifting about a week beforehand by cutting theround each plant with a spade, 6 in. away from the stem. This will encourage fibrous roots to form within the soil-ball. Give them a good watering before lifting. Also give them a good soaking once they are inside, spray them over with water, and shut the ventilators for at least a week to help them recover from the check of lifting. From then on give them as much ventilation as the weather will permit as this will help in preventing damping and various other troubles.
Before the chrysanthemums are taken into the greenhouse they should be sprayed to kill any insect pests and diseases which they may be harbouring. For insect control use gamma-BHC and then, some time after applying this, spray the plants with a sulphur fungicide to combat diseases. Also, the pots should be scrubbed thoroughly to remove any dirt and so on. The greenhouse must also be scrupulously clean when the plants are taken inside.
One important point when bringing plants inside is to carry them in pot first. This reduces the risk of damaging the buds or breaking the shoots off by catching them on the door frame. If the pots are being placed on an earth floor or on a soil border then put a tile or slate underneath each one to prevent worms and slugs entering the pot. Chrysanthemums can be placed much closer together in a greenhouse at the risk of losing a few of the bottom leaves than when they are outside during the summer. When staging the plants remember always to place the tallest plants at the back with the shorter ones in the front.
Cutting Back and Boxing
As soon as flowering is over, the stems of your chrysanthemum plants should be cut down to within 9 in. of the pot and the stools boxed up as I explained for the early-flowering types. The stools can be given warm water treatment if facilities are available. The boxes of stools are then kept in the greenhouse – not placed in cold frames as is done with the earlies.