Early sprays are an ideal introduction to chrysanthemum growing.
They will happily grow outside without any protection whatsoever. No greenhouse, covers or bags are needed at flowering time and even the first time grower can produce encouraging results. They can be grown equally well in the garden or pots. The best time to take delivery of your rooted spray cuttings is late March in the north and early April in the south.
Although pots can be used, they are better planted 12 to 15 to a standard seed tray. A tray will not dry out as quickly, take up less room and be easier to handle. Use a compost that is tried and trusted and both soilless and John Innes types can be successful. Chrysanthemums do however seem to prefer a compost with an open structure and at least some soil content.
A simple answer if only a few plants are being grown is to add 1 part good quality garden loam to 3 parts multi purpose soilless compost which should be medium grade not fine. The compost should be moist and they should be lightly watered and placed in a cool greenhouse in good light but shaded from the sun until they recover. They should only be watered when they show signs of flagging. Protect them from frosts. After 3 – 4 weeks they will need moving on.
Again trays or boxes are best but if you are happy with pots use them. A 5in or 13cm full pot is the correct size. Put 6 plants to a standard seed tray. Now the best place for them is a cold frame and give increasing ventilation when the temperature rises above 10 deg C (50F) in the frame Chrysanthemums relish cool airy conditions. They will need stopping, i.e. the removal of the growing tip, Early May in the north and late May in the south. The better the ground is prepared prior to planting out the better the end result will be. Add some form of humus and 4oz per square yd of a fertiliser that is approximately balanced in NPK analysis.
Planting out can commence from about 10th May in the south and 10 to 14 days later in the north. They should be given plenty of space, 18 to 24in if possible. Overcrowding should be avoided as it increases the chances of pest and disease attack. Alternatively they can be potted up into large pots, about 9in will do. Of course plants in pots need more attention than those in the garden, watering feeding etc. The plants will also need support from now on. There are several ways this can be achieved. Most early sprays are around 3 to 3½ ft high so 4ft canes will suffice.
The easiest way is to place 3 or 4 canes around the plant and periodically tie string around the outside of the canes. A better way is to tie each of the retained shoots that emerge from the leaf axels of the stopped plant to its own individual cane. For better quality results the number of shoots or breaks as they are known should be restricted to 3. The plants should be sprayed regularly with both an insecticide and fungicide to deter pests and diseases.
The only remaining task is carried out when buds appear in July. It is best to remove the centre bud as it is usually larger and earlier than the others and its removal will enhance the quality of the spray. If you wish to try and root your own cuttings the following year you will need to save plants. In late October or early November cut down the plants and leave about 6in of stem. Dig them up and trim off all green growth with secateurs and small scissors. Lightly trim the roots as well. Place the stools as they are known 8 to a seed tray in fresh compost.
Ovewinter them in a cold greenhouse, protecting them from bad frosts The odd degree of frost will not hurt them. Keep them on the dry side and only water them in a morning and when no frost is forecast. Carry on spraying them regularly. By March cutting material should be available. About 2in is the correct length of cutting, A small electrically powered standard seed tray type propagator will hold about 24 to 32 cuttings use a good quality soilless compost and rooting hormone powder. Water in well. Shade them from the sun and do not allow the greenhouse temperature to rise too high. They should root in about 3 weeks.