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cosmosPropagation & harvesting guides

Please refer to the general growing guide for more in-depth information on growing processes.

Cosmos bipinnatus ‘Gloria’

Colour: Rose flowers with a carmine centre.

Height: 70cms – 1m

To purchase seeds from this variety please visit our online shop - thank you.

I’ve grown Cosmos three out of the last four years on our flower farm.  I didn’t grow it in the third year as it was a particularly wet summer and the blooms were affected and for some odd reason I took it out on the poor flowers! Also, it also doesn’t have amazing vase life, so I dropped it. But the reality was - I REALLY missed their big, smiling blooms and found myself pinching some buckets from a fellow grower to use in my floral arrangements. Lesson learnt – and now it’s a staple in my cutting garden, every year!


Sow seeds indoors from March – April onwards.  Sow into seed compost and lightly cover the seeds.  You can sow seeds into a seed tray or individually into plug tray compartments or little pots.  Watch out for slugs even at this stage.  I once was waiting weeks for seeds to germinate until I realised that slugs had been eating them as they were emerging – leaving me with nothing, very frustrating!


Seedlings sown in a seed tray will be ready to be pricked out very quickly.  I always use a deep plug tray (individual pots will also work very well) as they develop their root systems very quickly.  Cosmos is not cool hardy and cannot be transplanted into their permanent position until all danger of frost has passed.  As during the germination stage please be extra vigilant for slugs – they are particularly fond of baby Cosmos seedlings (especially in the greenhouse) and it is just so disappointing to see your hard work eaten before it has a chance to even bloom!


If you intend on using Cosmos mainly as cut flower I strongly recommend giving it some support. This will help to keep the stems more upright.  Also – Cosmos is shallow rooted but produces masses of strong, thick stems which are a target on a windy day, so support would benefit, especially in a exposed area. 

Dead – head / remove any unused flowers to keep the plant continuously flowering for longer – this can be time consuming as it produces many flowers very quickly but do your best and you will be rewarded. 


Cosmos has quite a short vase life which can be extended if stems are harvested when the flower buds are still semi-closed or just opening.  In order to encourage long stems, make initial cuts deep into the plant, this will remove a lot of the plant at first but don’t worry – long, strong stems will follow.