Known colloquially as crepe (or crape) myrtles, these are excellent deciduous trees for suburban Sydney gardens. They are unfazed by hot summers, need very little attention and will grow in ordinary soil. The original species grows to a height of around 6 to 8 m. They are in full bloom in from January to March, with generous trusses of soft, crimped blooms in colours of pinks, white, reds, mauve and deep purple, forming a pretty backdrop to summer border flowers. Petals fall to make a carpet below. The trees have wonderful smooth young bark in attractive patterns, revealed each summer after the old bark has peeled off. They have a beautiful open vase-like shape if not pruned, which forms an attractive framework in winter.
Traditionally, the trees were pruned very hard every winter to ugly stubs in order to create a mass of bloom on straight stems fanning out from the pruning point, but these days we tend to appreciate more the natural shape of the tree left to its own devices, pruning only to shape wayward or congested branches, and making all cuts flush with the main stem or another branch. The leaves turn to pretty golden and red tints in autumn in Sydney, and all-in-all, the crepe myrtle is a good choice for a small garden. They grow best in full sun and such a position will minimise problems of powdery mildew, which older varieties were subject to in our humid summers. Newer types (such as the 'Indian Summer' hybrids, which cross Lagerstroemia indica with lagerstroemia fauriei, and which are named for North American Indian tribes) are supposedly resistant to this fungal disease. Avoid disturbing the surface roots or trunk of the tree with a whipper snipper or lawnmower, as this may result in suckering. If this happens, the suckers should be cut off as low down as possible. It is probably best not to have grass growing up to the trunk, to avoid this problem.
There are a number of named hybrids, including trees to 6 m (such as pale pink 'Biloxi' and white 'Natchez'), multi-stemmed shrubby varieties around 3-4.5 m tall (such as white 'Acoma' and bright pink 'Hopi') and miniatures growing to 1 m or less (such as lavender-blue 'Cordon Bleu' and mauve-pink 'Delta Blush') for very small spaces or pots. The Magic Series includes three varieties that grow to about 1.8 m in height: 'Coral Magic' (coral-pink flowers), 'Purple Magic' (rich purple blooms) and 'Plum Magic' (fuchsia-pink flowers with leaves that are deep purple when they first appear). These three varieties may rebloom if deadheaded after their first flush of flowers. These dwarf types benefit from the hard pruning technique, and can be cut back to about 30 cm in height in late winter, to make a more compact shrub. I have seen one of these grown as a standard, which looked good.
Another set of interesting hybrids is the Diamonds in the Dark series, which have become available in recent times. These specimens are more compact than the traditional tree-like crepe myrtles and they grow to around 3 m in height and 2.5 m in width. The leaves really are almost black and there are various different coloured flowers available - white, pinks, reds and purples can be obtained. These plants are suitable for hedges or as a background for a mixed border. Sadly, I haven't had much luck with these ones. Gardening friends have told me the red one does quite well.
Branches of crepe myrtle in bloom can make spectacular arrangements in a large vase!