Chrysanthemum : Greenhouse Plants
C – cool, minimum of 7°C (45°F)
fratescens is sometimes called Marguerite although I am sure I have heard the same name mistakenly applied to the hardy herbaceous perennial C. maximum. These very attractive shrubby plants from the Canary Isles have white daisy-like flowers and rather decorative foliage. Hybrids give larger flowers and range of flower colour such as C.f. ‘Jamaica Primrose’ which has yellow flowers and C.f. ‘Vancouver’ which is pink. Cuttings can be taken spring, summer and autumn. Plants are easy to keep. Shoots can be pinched out to encourage bushy growth or they can be trained into standards using the same procedure as for standard . They can be stood or planted outside the greenhouse during the warmer months but will not tolerate frost.
The plants most people think of whenis mentioned are an extremely variable group of hybrids catering for a wide range of preferences and uses. The routine for most of the pot chrysanths is the same. Cuttings are taken during winter or very early in the year. They are grown on with much attention to potting on at the right time into a rich John Innes loam and fed well as soon as they are established in their pots, initially with a high nitrogen feed and, as they build up to flower, twice weekly with a high potash feed. As soon as there is no danger of frost plants can be stood outside in a good sunny position for the summer with some support against strong winds. Before frosts and gales start in autumn bring the plants inside and give them very cool airy conditions until they flower. Unfortunately, they do take up a lot of space which makes it difficult for a small greenhouse owner to grow many. After flowering, the plants should be cut hard back to within short stalks of the roots. Plants are taken from their pots, as much as possible knocked away and the root bundled into deep seed trays with compost packed around them. They are kept very much on the dry side and cool like this until a few weeks before are needed when they can be warmed up a little and watered to produce shoots.
The type of plant grown will vary depending on what they are to be used for. The huge exhibition blooms the size of footballs such as C. ‘Charles Shoesmith’ are arrived at by much disbudding and removal of sideshoots so that only one stem per plant develops and only the main central bud is allowed to grow. Spray chrysanths must be the most popular for everyday cut flower uses.
Plants are stopped once or twice to promote several stems on which the flowers can grow. Cascade chrysanths are only really for those with much space and time because to make good showy display plants out of them, huge fans of cascading shoots are trained involving much work in the way of stopping so that the small pretty flowers are produced over as much of the plant as possible. The best pot display plants for a smaller greenhouse must be the charms. These grow naturally into a small round plant which is an amazing ball of small flowers when in full bloom. Large specimens of these can be had by the usual cuttings in winter method. However, smaller more manageable plants can be grown by sowing seed early in the spring. There are of course many more different types ofand they are great fun to grow and experiment with. All are short day plants, needing a minimum of 9-1/2 – 10 hours of darkness every night to initiate flower buds. Of course the amount of light they receive can be artificially controlled. Personally I dislike the concept of making them flower all year round as the commercial growers do. For me the sight and smell of chrysanthemums are part of the autumn scene. Plants bought out of season in flower are often very small as they have been made to initiate buds at this stage in their growth. If you propagate from them and grow on naturally they will inevitably grow into taller plants.