species, hybrids and cultivars
For a long time, the most common form in local gardens was Tabernaemontana divaricata 'Flore Pleno', usually known as mock gardenia. It looks similar to a gardenia - without significant fragrance, unfortunately - but is easier to grow, although. A fairly open shrub 2-3 m high and almost as wide, but could be lightly pruned to maintain a more compact form if desired.
There are now some compact forms of Tabernaemontana now on the market, notably T. corymbosa 'Little Emerald', that are being popular for small hedges and topiary.
These were discussed in more detail in the 14-01-2022 edition of Get Results Gardening, a weekly email publication for Australian gardeners, especially those in the tropical, subtropical and warm temperate parts of the country. If you request a free trial (see to calyx.com.au/getresultsgardening.html for instructions) you can ask for a copy of the 14-01-2022 edition to be sent as well if you want to read the Tabernaemontana article.
Tabernaemontana in the Landscape
Pictures will continue to be added here to give you an idea of growth habit and how you might position and prune these plants. All the photos so far were taken in Brisbane. Click for larger images.
Tabernaemontana divaricata, single form
Mock Gardenia (Tabernaemontana divaricata 'Flore Pleno')
Probably Tabernaemontana corymbosa 'Little Emerald'
Probably Tabernaemontana corymbosa 'Silver Rain'
The two varieties trained as contrasting small hedges