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Or buy this as part of our The Taj Mahal Collection.

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Cosmos bipinnatus 'Purity' has large, open flowers of pure white, with delicate apple-green foliage. The classic cut flower and a supremely lovely garden plant, which no one should be without.

Cosmos last 10 days in the vase, produce at least two buckets of cut flowers a week from a 1 x 1m patch and do so from late June until November – so that's nearly 50 buckets of flowers in one season from a small patch. They are impossible to beat.

Genus Cosmos
Group/Species bipinnatus
Variety Purity
Type Half-Hardy Annual
Common Name Cosmos
Border Position Back, Middle
Soil Type Chalky, Neutral
Scent Unscented
Site Full Sun
Moisture Moist but Well-drained, Well-drained
Height 1m (3ft 3in)
Spacing 45cm (18in)
Sowing, Seeds, Planting Sow under cover in mid spring and plant out after last frosts, or direct sow early May.
Care Tips Pinch out tips at 15-20cm to encourage bushier plants. Needs staking.
Flowering July - October
Vase Life 7-10 days, no conditioning needed. Pick fresh straight into water, just as the buds are about to bloom, and do not pick in the heat of the day. Deadhead the main blooms that are drooping and going over after about a week. Place out of direct sunlight.
Harvesting Flower production: 4-5 months.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
  • Sow Under Cover/Plant Indoors
  • Direct Sow/Plant Outdoors
  • Flowers/Harvest
Advice & Videos
Cosmos summer flower arrangement

In this video, Sarah shows you how to put together a lovely roadside-inspired Cosmos 'Purity' flower arrangement.

Summer flowers for pollinators

This is the time of year for wild dreams when it comes to plans for the summer garden.

Annual flowers – create summer colour

Create summer colour with these unbeatable annual flowers. Sarah's absolute favourites for reliability and colour.

Annual flowers for pots

If you want beautiful flowers for your pots this summer these are my top favourite annual flowers to grow.

How to plant and grow cosmos

Even if you only have a tiny garden – or just some pots – you have to grow at least one cosmos. They are the lowest maintenance,...

Direct sowing seeds

Learn how to get great results when direct sowing hardy annual seeds.

How to get summer colours in an autumn garden

For an abundant autumn, plant smart and you’ll be enjoying beautiful flowers for months.


Plant Delivery - When in stock, please allow up to 2 weeks for delivery.

Seeds Delivery - When in stock, please allow up to 1 week for delivery.

Next Day Delivery - Available for next day delivery if ordered before 12:30pm, Monday to Thursday. Applies to in stock seeds and hardware items only.

Click here to find out more information about our delivery rates and times.

Cosmos bipinnatus 'Purity' reviews

* * * * * Average based on 53 reviews

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Reviewed 30th November 2018 by Adriana

What a stunner. This was all over my garden and continued to flower till the end of September. A wonderful and robust plant.

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Reviewed 21st November 2018 by Jennifer

Same wonderful plants and service

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Reviewed 16th November 2018 by Margaret

Service good. I thought at first I'd made a poor purchase but they have been blooming the last few weeks and look splendid.

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Reviewed 14th November 2018 by Julie

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Reviewed 14th November 2018 by Emily

They were HUGE and absolutely covered in buds but despite being in a sunny spot, didn't flower until just before frosts!

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Reviewed 14th November 2018 by Glenny

a little late in flowering, but once they got going, all good

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Reviewed 14th November 2018 by Maureen

Excellent flowers but not as profuse as the Candy Stripped Collction

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Reviewed 14th November 2018 by Kate

Marvellous for cutting, vase after vase of much admired flowers. Lasted well into November.

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Reviewed 13th November 2018 by C Payne-Johnson

good plants which thrived

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Reviewed 9th November 2018 by Isabel

Service is always good tge seedlings were strong and healthy,New year but despite planting them at the same time as cosmos dazzler which I grew from seed - cosmos purity was late to come to full flowering, which in our northern climes means not flowering for long! Not the fault of the seedlings.

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Reviewed 8th November 2018 by Yvonne

They were perfect. I tell everyone to buy from SR if you want Cosmos that stand head and shoulders above other suppliers.

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Reviewed 7th November 2018 by Helen

Great service and beautiful display of flowers adding to my vegetable garden. Still flowering in early November.

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Reviewed 7th November 2018 by Judith

Seedlings arrived in good condition. They did brilliantly in the garden - are just about still blooming. Not so good in pots - probably due to insufficient watering in hot summer!

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Reviewed 7th November 2018 by Polly

One of the plants didn't survive but the rest were glorious and flowered profusely till the frost 'got' them, making them look very sad - and there were still plenty of buds to bloom too.

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Reviewed 7th November 2018 by Ruth

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Reviewed 7th November 2018 by Christopher

All very straightforward, well packaged, quality product.

Extraordinarily robust plants, grew to over 6 feet high with main stems like 1 - 2 inches thick bamboo, had to be cut down with tree loppers. Flowered vigorously for months and kept on growing, and growing, and growing......

* * * * *

Reviewed 7th November 2018 by Hazel

Excellent service. Plants arrived in good condition. Will order again next year. Recommended to others,

* * * * *

Reviewed 31st October 2018 by Peggy

Always a winner and this year no exception

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Reviewed 11th October 2018 by Jane

Excellent and still looking great

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Reviewed 3rd October 2018 by Janet

Though flowering very late they are stunningly beautiful in my borders. Some are 5ft tall. They stpre my favourite Cosmos variety. They are though very karate flowering as I hadn't got borders ready sooner for planting. I also put them meantime into plant pots in tioo Rich a compost as well as pinching out budding tips to harshly in the hope the seedlings would bush out.
I gave them a hard time but they've excelled their beauty and are delicately enhancing my borders alongside Bishop of Llandaf dahlias. Though in strong contrast they really are giving me great joy. In another border they are wafting amongst Verbina flowering stems and flowering Grasses.
I will take photos but have forgotten how to email photos, sorry! If motvtoo latecwiolnsend onnwhen have help.,

* * - - -

Reviewed 3rd October 2018 by Tracey

Only 3 of the seedlings grew to the expected height and flowered. Very expensive for what they are - I will stick to the seeds next year as they are extremely easy to grow.

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Reviewed 3rd October 2018 by Pamela

Fantastic they are huge 6 feet tall and still flowering well

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Reviewed 3rd October 2018 by Juliette

As with all your plants in excellent condition on delivery.

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Reviewed 3rd October 2018 by Sylvia

Service and plants were good.

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Reviewed 20th September 2018 by Sheila

I had fantastic lush green foliage, very tall and thick stemmed. Flowered quite late. The strong winds this week have completely blown them over and snapped the stems

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Reviewed 20th September 2018 by David

Plants arrived as scheduled in excellent condition then continued to grow on with no check. They made large plants which flowered continuously throughout the Summer and were still in flower last week when I had to move them to make way for Spring plantings.

* * - - -

Reviewed 19th September 2018 by Gloria

Didn’t last long . Probably the intense heat

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Reviewed 19th September 2018 by Jane

The seedlings arrived well packaged and in good condition.The seedlings are a good size, I potted them on and planted out after the risk of frost was gone. I have them in my front garden and they are still providing an eye catching display, I dead head regularly.
They appear to be expensive, however the quality of the product makes them good value for money.
I will be purchasing more seedlings next year..

* * * * *

Reviewed 19th September 2018 by Susie

Beautiful, healthy plants. Still going strong.

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Reviewed 19th September 2018 by Arthur

see above.Service excellent, plants arrived as stated. No complaints.

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Reviewed 19th September 2018 by Jayne

The service was excellent and I am delighted with my purchase

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Reviewed 17th September 2018 by Gilly

Very poor. Two were broken and had to be thrown away.

Reply from the Sarah Raven Team:

"Thank you for leaving your review. We are very sorry to hear of your disappointment with your cosmos and have refunded you for them."

Posted 7th November 2018

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Reviewed 16th September 2018 by Olive

Late flowering. Very tall plants and no flower until August. Looks like we are going to enjoy flowers well into the Autumn. We were the first area to have a hose pipe bann

* * * * -

Reviewed 15th September 2018 by Judy

one planrt didn't have any petals on the flowers. most peculiar!

* * * * *

Reviewed 15th September 2018 by Mrs Davies

Again grown well and flowering constantly excellent

* * * * *

Reviewed 14th September 2018 by Hilary

Very good, still flowering strongly, tall and strong.

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Reviewed 12th September 2018 by Michael

My previous comments apply. Speed of service on the purchase of all items was good

* - - - -

Reviewed 12th September 2018 by Janet

My order contained the wrong colour plants - bright pink not white, as ordered and two different varieties - short and bushy and long and thin.
The display in the white garden looked ridiculous!
Extremely disappointing purchase - will not order from this retailer again.

Reply from the Sarah Raven Team:

"Thank you for your review. We are very sorry to hear that some of your cosmos 'Purity' have flowered incorrectly. We note that you have been refunded for the seedlings and apologise for the disappointment."

Posted 7th November 2018

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Reviewed 12th September 2018 by Penelope

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Reviewed 5th September 2018 by Sheena

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Reviewed 3rd September 2018 by Miss Chapman

They are still flowering madly. If I can manage to attach a photo you will see that I have a Cosmos forest!

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Reviewed 3rd September 2018 by Susan

Have flowered but were very tall when arrived, and have remained very gangly

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Reviewed 3rd September 2018 by Penny

They were brilliant as always

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Reviewed 3rd September 2018 by Sally

Lovely tall bushy plants with lots of flowers

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Reviewed 2nd September 2018 by John

I like this plant. Tall, pretty and good value.

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Reviewed 2nd September 2018 by Molly

Unlike the previous ones these were OK - once we had a bit of rain, and are currently in full bloom. I think the Cosmos 'Purity' is a fabulous plant.

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Reviewed 2nd September 2018 by Jonathan

Prolific greenery and lots of flowers.

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Reviewed 29th August 2018 by Mrs Khor

Weeks and weeks of flowering,good tall sturdy plants.

Goliath Cosmos

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Reviewed 11th April 2018 by Joan Harley

I have also had the same problem with some Cosmos, Purity included, over the past 3 or 4 years. Pinching out does help, but not always. The plants left in large pots (in sun) suffer more than the ones in the beds (semi-shade). They become impressive strong, tall plants, not so feathery, and eventually flower in Septemeber through to the frosts. I have tried not feeding the ones in the pots, it helps but not always. Frustrated that I haven't figured it out though! Good to know I'm not alone!

Cosmos Purity & Dazzler

* * - - -

Reviewed 17th November 2014 by ELIZABETH WALKER

Grown as usual from seeds sown outside in late April. Transplanted to south facing well drained border. Lots of feathery greenery, and plants grew to 8' but no flowers until September. What was wrong?

Reply from the Sarah Raven Team:

"Thank you so much for your comments. Cosmos really need a lot of sun, and thrive once pinched out, so this may be the reason for the late flowering.

For further information, please contact our Customer Service team or view our Instruction Booklets online."

Posted 18th November 2014

always reliably lovely

* * * * *

Reviewed 17th November 2014 by mary dunstan

Have grown this from seed for several years, and they always do well, in sunny and not-so-sunny sites. Only in late November are they tailing off. Elegant both in flower and leaves, and an excellent foil to many other plants. A true garden essential.

Cosmos - not good cut flowers at all

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Reviewed 13th August 2014 by Wendy Carter

I grew these cosmos for cut flowers on the basis of this recommendation but am terribly disappointed. Contrary to the claim, I have consistently found that they last only a few days as cut flowers. The ones I cut on Saturday I have thrown out today, Wednesday. this is typical of my experience of them. So just leave them in the garden where they look great.

Reply from the Sarah Raven Team:

"Thank you for your comments. We asked the team at Perch Hill to check this out for us, and this is what they came back with:

"It's now day 6 and I had to deadhead the main blooms that are drooping and going over, but the buds on the stems are now opening so taking over and the foliage still looks very fresh. I would propose that the customer may just be picking one flowering bloom on a stem that's a few days old and then goes over or droops after 3 days. Or if she is picking stems with buds too she is doing something wrong: picking in the heat of the day, picking old blooms, putting on a hot sunny windowsill, cutting the stems and letting the stem ends get dry before putting into water so preventing water uptake."

Make sure to pick fresh blooms, cut the stems straight in to water and they should remain looking really fresh. Make sure to do a bit of deadheading, and in the vase they should last 7-10 days. Let us know how you get on, and you can find further advice at http://www.sarahraven.com/articles/the_basics_of_arranging_cut_flowers.htm"

Posted 20th November 2014

flowery blowsy

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Reviewed 27th June 2014 by Vanessa Wagstaff

Cosmos was one of the first annuals I discovered after studying gardens in books. It worked very well and easily, with a beautiful froth of cut flowers. This year I've been rather late getting them in the ground and they have grown shorter, but normally they are a good 4-5 foot high in richer soil. Just wonderful for the house.