By the time chrysanthemums are in bloom around August, the winds and rain may easily destroy them. In Holland at DecoNova, the chrysanths were growing outside (planted on May 18), in an open-sided polytunnel to protect them from the worst of the weather, and this is how many exhibition growers get the best out of them in this country, too.
But not many of us want to give up space to grow things under a plastic tent. As an alternative system, we plant our chrysanths in ever-bigger pots at Perch Hill. Some are in five-litre and some in 10-litre pots this year. We plant them in a good rich, soil-based compost in the spring, and then in May, the chrysanths – pot and all – are sunk into a bed in the cutting garden.
- Our chrysanthemums are sent out in sets of rooted cuttings. If you have a greenhouse or coldframe, get the plants in early spring and pot them on. If not, get them in summer, almost ready to be put out.
- When you receive the young plants, pot them on into 7cm pots of soil-free compost and keep them somewhere frost-free with lots of light. They will be ready to go out into the garden when they're roots have filled the pot, or around mid May.
- Plant them in a sunny but sheltered spot, in well-drained soil that has had some compost and fertiliser dug in. Space the plants about 20cm (8in) apart (but this will vary according to variety; some are more vigorous than others).
- After planting, water generously for 1-2 weeks so the plants get well established.
Pinching Out or Disbudding
As with almost every plant you grow for picking, you want stocky, stout rugby players rather than spindly athletes. So once they reach 6-8in, we pinch out spray chrysanths, removing the top growth and 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.
You can use what you remove as a cutting – see How to take chrysanthemum cuttings for more info.
If you like one large shaggy flower, you should grow the large-headed blooms – not the sprays – and will need to disbud. This is a similar technique to training tomatoes – removing all the side shoots as the plant grows to create one strong stem.
Chrysanthemums, like dahlias, tend to break at the base of the stems so staking is key. By the time your chrysanths are at their peak height, autumn gales and rain will be on the way too.
The stakes should be tall enough to accommodate the plant, but short enough for the flowers to stand proud of it; check the height of the varieties you have purchased.
At Perch Hill, we tie them in individually to their own cane, or grow a whole bed up through netting stretched horizontally at about 18in from the ground.
Bringing them in
When the weather starts to get savage – not cold, but wild – we lift the dahlias in their pots and bring them into a greenhouse to fill the tomato beds. It's a successional system that works well and gives us plenty of flowers to pick until Christmas.
When flowering is over we dry off the plants, cut them down and store them in a frost-free place. The roots will shoot again in spring. Re-pot and off you go again.
Last winter I experimented with a technique I use on dahlias, where the plants are left in the garden and mulched, but it was not a success. Stick to the old ways.
Growing chrysanthemums indoors
Some chrysanthemum varieties should ideally be grown indoors – in a greenhouse or protected growing space of some kind – and will then flower from mid/late November until Christmas. Varieties that should only be grown indoors include 'Anastasia Green', 'Froggy', 'Porto Purple'. Most other varieties can be planted indoors or outdoors.
If you have soil beds in your greenhouse, the rooted cuttings can be planted direct, spaced at 30-40cm, and watered in well. Pinch out and stake your plants as you would for outdoor varieties.
Alternatively you can grow your chysanths in large pots, about 35-40cm in diameter, to move outside in good weather:
- Fill the pots with John Innes No 2 compost and plant one cutting per pot. Water in well. Insert a stake at their side which you will tie them to as they grow.
- When the frosts have finished, place the pots outside in a sunny, sheltered spot.
- Pinch out as you would for outdoor varieties, to encourage side branches and produce bushy plants.
- Water freely throughout the summer and give them a balanced feed every two weeks from midsummer until the flower buds start to appear.
- Bring them back inside before the September gales arrive, and pick the flowers from there.
- Cut the plants back when they finish flowering and store frost-free over the winter.
Find out more about how to extend the vase life of Chrysanthemums.