Do osteospermum come up every year?

With proper care Osteospermum will come up every year.

Osteospermum should be given a general Phostrogen (Phosphorous/Nitrogen based) fertilizer) to help promote flowering.

Osteospermum should also be watered well for the first 2 weeks after planting and then watered regularly to keep the soil from becoming dry. They also prefer sunny locations so be sure to plant them where they'll receive plenty of sunlight

However, they are not a very hardy plant in colder climates. So it is generally recommended to take cuttings to propagate to ensure that you'll be able to continue to enjoy your Osteospermumevery year.