Indoor Flowering Plants – Caring for Chrysanthemum Plants
Soil for Indoor Chrysanthemums
The indoor flowering plants –– are grown in pots, so we must decide on a suitable potting compost in which to grow them. I always use John Innes No. 1 Potting Compost for the first and second potting, and for the final potting John Innes No. 2.
Pot Sizes and Potting
Young chrysanthemum plants which have been raised from cuttings are first of all potted singly into 3-1/2 in. pots. When they are established in these about mid-April they are transferred to 5 in. pots, and when well-rooted in these the end of May or early June they are potted finally into 8 in. ones. I do not think that 9 in. or 10 in. pots are really necessary except possibly for large plants which are grown for exhibition the 8 in. Size is usually adequate for the average gardener. During the final potting I like to leave about 2 in. between thesurface and the top of the pot for a topdressing of compost during August or early September. This supplies the plants with a little extra food which helps them along. Always pot chrysanthemums firmly to obtain the best results, using a wooden potting stick.
Starting with Young Rooted Cuttings
As soon as the cuttings of your chrysanthemum plants have rooted early in the year, they should be potted off separately as I have just mentioned. If you intend to plant them in the open ground for the summer, as is sometimes practised, instead of growing them in pots, then they can be placed in seed boxes and planted out from these. Space them out about 2 to 3 in. apart each way in the boxes. When removing the rooted cuttings from their containers they will receive a slight check, so cover them with sheets of newspaper after potting to help prevent flagging. Remember to insert a label with the name of the variety in each pot.
Chrysanthemums should not be subjected to high temperatures or soft, weak plants will result. I think that a lot of people give them too much heat and they do not obtain the hard, sturdy plants which are desired. Young rooted cuttings which have been potted up should be given a temperature of around 4° to 7° C. (40° to 45° F.), and this is also an ideal temperature range to maintain for growing them on.
The young plants should be given all the light possible once they are established in their first pots. It is important to give them plenty of room on the greenhouse bench because if the pots are packed close together the plants will become drawn up or ‘leggy’. By giving them adequate space the leaves will be retained right to the base of the plants.
For the first few days after the cuttings have been removed from the propagating case and potted up, the greenhouse should be kept fairly close, but once they are established the ventila-tion should be increased gradually. After this period plenty of ventilation may be given when-ever the weather is reasonable. Open the top ventilators and also the side ones when possible.
By mid-March, if some of the young chrysanthemum plants are well hardened off, they can be placed in a cold frame and hardened off further by gradually increasing ventilation the sooner they are in frames the better as you will then obtain good hard plants. I sometimes risk standing mine out-side from early May and protect them by placing straw bales or screens of polythene sheeting around them.
The reason for stopping is to encourage a plant to form shoots and flower buds earlier than it would naturally, which will in turn give us blooms earlier in the season and at the time we want them. Generally this task is carried out from the middle of March to the end of April or early May, giving a second stop in June or early July depending on the variety, the time when the cuttings were taken and also the area in which they are being grown. Most catalogues give stop-ping dates (or a stopping ‘key’) for each variety, and state whether it needs stopping once or twice, but this is only a rough guide and the times of stopping are best gained through experience.
All that is involved is the removal of the growing tips of the plants to encourage the side shoots to develop. Pinch out the tips between finger and thumb. It is exactly the same procedure as for the outdoor chrysanthemum plants.
This may be necessary from the time the young chrysanthemum plants are in their first pots, in which case a thin bamboo cane will be sufficient. After they have been put into their final pots a strong cane (about 4 ft. in length for tall varieties) will be needed for each plant to prevent the stems being broken off by the wind. Some gardeners, especially those growing exhibition blooms, use three or four canes per plant, one being provided for each shoot. Use either raffia or soft green garden twine for tying; do not tie the stems too tightly to the cane, but leave room for them to develop.
As with the early-flowering chrysanthemum plants, there are many hundreds of varieties from which to make a choice. Again I would suggest close study of specialist catalogues; visits, if possible, to the collections of enthusiasts in your district, and to flower shows where chrysanthemums are on display.