These are the largest blooms in the chrysanthemum world and are classified in sections 1 and 2 of the National Chrysanthemum Society classification system and are colloquially known as “japs”.
You will require a greenhouse or conservatory in which to flower these since the time of flowering is late October/November and protection is required from the weather at that time of year.
The best source of cuttings for large exhibition is from an amateur nurseryman, Ivor Mace (www.ivormace.com) and for the medium exhibition Beechwood Chrysanthemums (0151 4263164).
These rooted cuttings should be obtained in March and potted up into 9cm pots in a greenhouse or conservatory and grown on, after approximately 4-5 weeks these should be re-potted into 13cm pots in both cases using either a soilless compost or John Innes no.2 – if using the latter add a little extra horticultural grit to the mixture. At the beginning of June they are then re-potted into their final 22cm pots using the mixtures as before.
During their time in the 13cm pots around the 15 May pinch out the growing tip of the plant and the result of this is that shoots will start to grow from the leaf joints below where you have pinched out the growing tip – allow the top 2 of these to develop and remove the rest.
Through the summer months the plants should be grown outside watering as required, 2 x 5’-0” canes should be inserted in each pot and the plant tied to these for support as it grows – in turn the canes should be tied to a horizontal wire support for stability during windy conditions.
From the end of June through to early September give a balanced general liquid feed around 1-2 pints once per week to each pot.
In August a bud will appear in the tip of each of the two shoots (laterals) being grown and the surrounding shoots which appear around each of the buds should be removed allowing the bud left to develop – once this is achieved then remove one of the laterals in 3 stages leaving just the one to flower.
The bud will swell and eventually in mid to late September will split it’s calyx to reveal the embryo petals and at this point should then be taken into the greenhouse/conservatory to flower – do not be afraid to give plenty of ventilation at this stage.
During the summer, as with all plants, watch for aphis/caterpillars and spray using a proprietary insecticide obtainable from your local garden centre.
The result of this will be a flower up to 22cm in size which will last for a considerable time.
It is suggested that you grow varieties (cultivars) which are relatively short in growth since these are more manageable and therefore try (say) Duke of Kent (white), Pink Duke of Kent (pink), Silver Gigantic (bronze) and Primrose Jessie Habgood (yellow) in the large exhibition and Trident (bronze), Woking Rose (pink), Idris (salmon) and Cossack (red) in the medium exhibition for an initial try.
Try one or two and you may surprise yourself with the results.
The following year you may wish to purchase rooted cuttings again or alternatively try and root your own – if you want to try the latter then you will need a little heat in the greenhouse or conservatory but if you want to give it a try then follow this routine.
After flowering cut down the plant to around 15 – 20cm high and leave until early January just giving sufficient water to keep the plant alive. The plants should be knocked out of their pots and the root ball trimmed to around 15cm square and 7.5cm deep and placed in a seed tray.
In early January put in good light and apply a little heat under the plant – if in the greenhouse then if you have electricity then a soil warming cable is ideal if not then place on the bench and put a small paraffin heater under the bench and in 3-4 weeks new shoots will appear from the soil and these should be taken as for any other plant – snap them off, dip in a hormone rooting powder obtainable from your local garden centre and put into a cuttings compost again available from said garden centre. These are then watered in and placed on your soil warming cable or over the heater and sprayed with a fine mist once a day and in around 3 weeks they will form roots and you are back to the same stage as the previous year with your bought in cuttings and the previously outlined procedure should be followed again.
Good luck.