How to grow osteospermum and best varieties

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.

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Key facts

PLANT TYPE Tender perennial

POSITION Full sun

SOIL Moist, fertile soil

How to grow osteospermums: month by month

Best osteospermum varieties

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Full test results for osteospermums

USING THE TABLE The more stars the better. OVERALL SCORE Ignores prices and is based on flowering duration 30%; flower impact 30%;foliage 20%; shape of plant 10%; pests and diseases 10%.

How we test osteospermums

The Which? Gardening magazine researchers 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.

Discover our Best Buy tomato feeds

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.