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Home>Flowers, Plants & Shrubs>Flower Seeds>Half-Hardy Annual Seeds

Cosmos bipinnatus 'Sweet Sixteen'

Just £2.99

Half-Hardy Annual
What is Half-Hardy Annual?
A plant that completes its entire life cycle (growth, reproduction, death) in one season.
Can be grown outdoors but requires winter protection from frosts and temperatures below 0C.
4 Reviews
1 packet (70 cosmos seeds) £2.99 Despatch: by Monday
Description Sowing More Info Delivery Reviews

Eye-catching soft blushed pink blooms, each have distinct darker pink picotee edges and an attractive double frill in the centre of each flower. Cosmos Sweet Sixteen is ideal for adding height and interest to borders as well as making an intriguing cut flower.

Cottage Gardens, Wildlife Gardens, Cut Flower Garden


Full sun

Up to 90cm (35.4in)

Up to 50cm (19.7in)

Easy for all

Easy for all

1 Packet (70 Cosmos Seeds) (TT08251)

Sowing Months Flowering Months
When growing Cosmos plants, water regularly until they are fully established. Deadhead faded Cosmos flowers regularly to encourage more blooms to be produced throughout the summer.

Sow Cosmos seed from March to May at a depth of 3mm (1/8") in a good quality seed compost, and cover the seeds with a very fine sprinkling of vermiculite. Place the seed tray in a propagator at a temperature of 18-25C (64-77F) or seal it inside a polythene bag. Keep the soil damp but not wet. Do not exclude light as this aids germination which usually takes 7-15 days.

When seedlings are large enough to handle, transplant into 7cm (3") potsand grow them on in cooler conditions until large enough to plant outdoors. When Cosmos plants are well grown and all risk of frost has passed, acclimatise them to outdoor conditions over 7 to 10 days. Transplant outdoors in full sun in any moist, well drained soil at a distance of 45cm (18") apart. Pinch out the growing tip of each stem when transplanting to encourage stems to branch and produce more Cosmos flowers.


Seeds and garden supplies will normally be delivered within the time period stated against each product as detailed above. Plants, bulbs, corms, tubers, shrubs, trees, potatoes etc are delivered at the appropriate time for planting and will be stated on the product page or in your order acknowledgement page and email.

Orders for packets of seed incur a delivery charge of £1.95.

Orders which include any other products will incur a delivery charge of £4.95.

Where an order includes both packets of seeds and other products, a maximum delivery charge of £6.90 will apply - regardless of the number of items ordered.

Large items may incur a higher delivery charge - this will be displayed in your shopping basket.

Please see our Delivery page for further details and details of any surcharges that may apply to certain destinations.

Satisfaction Guaranteed

For your complete peace of mind, our Home and Garden products may be returned to us within 30 days of purchase for a refund of the purchase price. Items must be returned unused, at your cost and in mint condition. All items carry a manufacturer's 12 month defects warranty.


My favourite Cosmos variety 2016-08-19

If I could only grow one variety of Cosmos it would be Sweet Sixteen. I love the two-tone colour of the flowers and although the plants are very bushy, they need no support. Masses of flowers, a truly lovely sight.

T&M replied on 2016-08-19: Thank you very much for your review. I am glad that you have been happy with your purchase. I hope we can continue to be of service to you in the future.

Beautiful cosmos variety. 2016-03-18

I grew this in 2015 and it was gorgeous. Flowering for months despite a wet and rather dismal Scottish summer, the blooms were plentiful and lovely. There was a little colour variation, with some plants producing flowers that were exact replicas of the seed packet, and others slightly darker or paler - all very beautiful.

T&M replied on 2016-03-19: Thank you very much for your review. I am glad that you have been happy with your blooms. I hope we can continue to be of service to you in the future.

New to gardening 2011-08-17

I am new to gardening, and this cosmos has certainly encouraged me. Every seed came up. They are like bushes. I am stunned. Flowered in June (I live in Kent) they are still flowering. Unless you need masses of plants don't plant them all at the same time.

Gorgeous 2011-05-08

bought these last year and sowed them quite late this spring (2011). Tall but very sturdy plants which started flowering late July. Most of them are true to the picture but a very few are a solid dark pink/purple, blending very well with the bicolour shown. Bought another packet already to sow next spring I like them so much.