Cosmos Double Click Rose Bon Bon Seedlings

Plant Cosmos Double Click Rose Bon Bon in well prepared, moist soil that ideally was enriched with a little organic matter the previous autumn. Not too much as Cosmos flower better if the soil is not overly rich. Water well after planting and for at least a week after that just to make sure they establish well.

Cosmos also grow very well in containers but remember that they can reach 100 cms in ideal conditions so we would suggest using pot sizes of at least 5 Litres and preferably a bit more. Any general purpose compost will do here.

The main requirements are that your plants have enough light and water - they grow very fast and flower hugely through summer so moisture is important. They can cope with a little shade but flower better in full sun. In general, they need an absolute minimum of 4 hours direct light a day, but 6-8 hours would be better.

Because you are buying seedlings, you can plant your cosmos into their final flowering positions immediately. Space your plants 35-50 cm apart and (in a bed) plant them in drifts of rather than singly. They will either need a 90 cms cane per plant (which should be pushed in about 30 cms deep and about 5 cm from a plant) or a support made of twine or pea/bean netting. This should be stretched between canes about 40 cms above ground level and the cosmos can then grow through it. It is not pretty at first but the plants disguise it very quickly and it is an effective solution (if you are anti-plastic, you can also make a cat's cradle of twine between canes around the outside of the planting). Just don't plant a group that is so big you can't reach the middle...

As flowers develop cut them or dead head when they are over and your cosmos will carry on flowering all summer long. A well-grown plant can quite literally produce a hundred flowers or so in a season.

To maintain flower quality and size, you can use a high potash and phosphate fertiliser every fortnight throughout summer Home-made comfrey tea is perfect or one of the specialised tomato fertilisers will do very well.