Chrysanthemums are one of those plants where the younger the stock the better the growth rate and flower density. That's why it's important to take chrysanthemum cuttings rather than relying on last year's plants. Chrysanthemum cuttings could not be easier to do – the technique is the same as for dahlias –and for every mother or grandmother plant, you can produce at least 10 of a new generation.
Any lifted roots or potted chrysanthemum plants you might have in a greenhouse or shed – or any hardy varieties you have in the garden – will have started to shoot in April. With a sharp pocket knife remove a few of the burgeoning stems, 2-3in long, from as near the base of the plant as you can. If your cuttings are longer than this, just use the shoot tip but remove the bud at the top. This encourages energy to go into developing roots, rather than top growth.
Push them into a gritty mix of compost, four or five to a medium-sized pot around the outside. I don't bother to use hormone rooting powder – they seem to root well without.
Enclose them in a tent of a plastic bag, supported on small sticks or canes and lay the pots out on sand or capillary matting so they can absorb water from below. If you have one, put them in a propagator or on a heated mat so they get a bit of bottom heat. This speeds up the rooting.
Keep the compost moist at all times and they should root in three to four weeks. Pot them up individually when you see roots through the hole in the bottom pot. Use 2½-3½inch pots of soil-free compost and keep them somewhere light and frost-free. They will have filled their pots and be ready to go out into the garden in mid May.
Plant out your chrsanths into ground that has had some compost and fertiliser dug or rotavated in, spacing them about 9in apart. Your home-made or spent mushroom compost are both fine additions and use a fertiliser based on seaweed or pelleted chicken manure. Chrysanths love the richness of both.
You want stocky, stout rugby players rather than spindly athletes to give you the best-looking and best-producing plants later in the year, so after a couple of weeks in the garden, pinch them out. This means removing the top growth, taking it down to three or four leaves up from the base of the plant. This promotes the formation of side shoots and you'll create a bushier, more flower-productive clump.
Staking is very important for chrysanthemums, as by the time they are at their full height the autumn gales and rain will be on their way. Make your stakes tall enough to accommodate the plant, but short enough so that the flowers are able to stand proud of it. Check the height of your variety and go for staking to one third that height.
For more information, see How to plant and grow chrysanthemums.