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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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PLANT TYPE Tender perennial
POSITION Full sun
SOIL Moist, fertile soil
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 |
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Variety name | Overall rating | Height x spread | Duration of flowering | Flower impact | Display | Foliage | Plant shape | Pests & disease |
---|---|---|---|---|---|---|---|---|
★★★★★ | 25 x 50 | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★★ | |
★★★★★ | 30 x 45 | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★★ | |
★★★★★ | 25 x 35 | ★★★★★ | ★★★★★ | ★★★★☆ | ★★★☆☆ | ★★★★☆ | ★★★★★ | |
★★★★★ | 30 x 40 | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★★ | |
★★★★☆ | 35 x 45 | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★★ | |
★★★★☆ | 25 x 35 | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★☆ | ★★★★★ | ★★★★★ | |
★★★★☆ | 30 x 40 | ★★★★★ | ★★★★★ | ★★★★☆ | ★★★★☆ | ★★★★★ | ★★★★★ |
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%.
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.
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.
Wherever you plant your osteospermums, water them regularly, especially during dry spells. During late summer, feed them weekly with a tomato food.
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Remove the faded flowers to the base of their stems to prolong the flowering season.
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.
Greenfly can quickly build up and cause poor growth by sucking the plant’s sap. Treat by squishing any colonies by hand.