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23 February 2021

How to grow osteospermum

Osteospermums, also known as African daisies, come in a huge range of colours, and are great for baskets and patio pots or for filling gaps in borders
Osteospermum
CT
Ceri Thomas

Osteospermums have a reputation for closing their daisy-style blooms on cloudy days, but there has been lots of breeding to overcome this, including double-flowered varieties that stay open no matter how overcast the weather, which makes them great for shadier spots too. 

Which? Gardening magazine grew a range of popular varieties to see which would give us the best display throughout the summer

How to grow osteospermums: month by month

January February March April May June




POT UP INDOORS POT UP INDOORS MOVE OUTDOORS FLOWERING
July August September October November December
FLOWERING FLOWERING FLOWERING PULL UP



Best osteospermum varieties

Best Buy osteospermums
What it looks like Variety name Height x spread
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25 x 50cm
A really eye-catching variety, it produced plenty of flowers. Each bloom had a ring of white petals with a hint of purple, and bright purple double centres. The neatly shaped foliage was a bright mid-green, which showed up the flowers well and added to an excellent display. The double centres kept the flowers open even on dull days. Unlike some other varieties, it flowered constantly from the end of June until the end of September.
What it looks like Variety name Height x spread
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25 x 35cm
The striking rich dark-red flowers of this variety are almost velvety, and the darker red veins on the petals leading into the central dark eye make each individual flower a little gem. The first flowers opened at the start of June, and by August the plants were absolutely covered in blooms, shown off by the neat cushion of long, oval leaves. The single flowers did close up a little earlier in the evening when the weather was overcast, but still gave a brilliant display during the day.
What it looks like Variety name Height x spread
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30 x 45cm
Another single-flowered variety, this one impressed us with a great show of cheerful daisy-shaped blooms in candy pink with a deep purple centre. The first blooms opened in June and the flowers kept coming until the end of September. The neat and compact habit, with attractively spiky green leaves, made it ideal for bedding or patio pots and containers. Like most single osteospermums, the flowers closed earlier in the evening on dull days.
What it looks like Variety name Height x spread
Member content
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30 x 40cm
A previous Best Buy, this white-flowered variety gave us the heaviest crop of all, peaking in early September. The pods were long, very pale green and a little hard to spot among the dense foliage of these vigorous plants. As with all white-flowered varieties, the seeds are white, too.

How we test osteospermums

We trialled 18 varieties of osteospermum. The plants were delivered as plug plants, which we grew in modules until they were large enough to plant out. We planted them out in a sunny area of our trial site in the Cotswolds at the end of May when the danger of frost had passed. We assessed them for flowering, vigour, foliage and any problems throughout the summer until the beginning of October.

Caring for your plants

Planting

Osteospermums often arrive as cuttings or plug plants, generally in late March or April. Pot them up in a Best Buy compost for raising young plants and grow them on in a light, frost-free place. 

They can then be moved to a sunny border after all chance of frost has passed in late spring. They can also be planted in pots using a Best Buy compost for containers and mixing in a Best Buy controlled-release fertiliser.

Watering 

Wherever you plant your osteospermums, water them regularly, especially during dry spells. During late summer, feed them weekly with a tomato food.

Deadheading

Remove the faded flowers to the base of their stems to prolong the flowering season. 

Overwintering

Although many osteospermums are often thought of as annuals, they are actually half-hardy perennials and can be overwintered in a light frost-free spot as established plants or rooted cuttings. 

Common growing problems

Greenfly

Greenfly can quickly build up and cause poor growth by sucking the plant’s sap. Treat by squishing any colonies by hand.

Read more about greenfly.

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