There are two autumn-flowering plants with the common name of naked ladies.
Amaryllis (Amaryllis belladonna) are closely related to clivias and hippeastrums. These large, pear-shaped bulbs flower in autumn. The flowering stems, which may be up to 1m (3ft) tall, appear before the leaves. At the top of each stem is a cluster of six or more pale pink, lily-like flowers. The flowers are followed by strap-shaped leaves, up to 40cm (15in) long and 4cm (1.5in) wide. Hybrids are also available in white (such as ‘Hathor’) and various shades of pink.
Amaryllis like hot, dry conditions, so a sunny position is best. Plant them in summer when they are dormant, with the neck of the bulb just protruding above soil level. They can be propagated in summer by separating small bulbs from the side of the parent bulbs. However, it may be several years before the clumps reach flowering size.
These plants are very easy to grow, and are suitable for all parts of Australia except for the hot tropics. In areas where temperatures fall below -5ºC the leaves may be damaged in winter, but the plants will recover. Grow them in a frost-free spot in cold climates.
Members of the genus Colchicum are commonly called autumn crocus (Colchicum autumnale and C. speciosum). They are not related to the true autumn crocus (Crocus speciosus), although they resemble them. True crocus do best in cold or mountain climates only.
Colchicums are sometimes known as naked ladies because, like amaryllis, the stems come up from bare ground in autumn and produce the flowers. The broad, fleshy leaves usually do not appear until the following spring. C. autumnale has mauve, narrow-petalled flowers. Forms with white and double flowers are also available.
A similar species, C. speciosum has broader petals, and also comes in white and deep purple forms. Like the true crocus, colchicums are adapted to cool climates and can survive severe frosts.
Colchicums can be planted in part shade under deciduous trees, or near the front of beds where the flowers can easily be seen. Plant corms in late summer. They like rich, well-drained soils and need plenty of moisture during the growing period, particularly if they have been planted in full sun.
Amaryllis and colchicums are available from the bulb section of your local nursery in late summer or from specialist mail-order bulb nurseries.