Gaura is a weedy, wispy wild flower. Gardeners enjoy the tall, lanky flower stems that are lined with white to pink, five-petaled blossoms that attract bees and butterflies. Gaura grown in gardens is usually a cultivar of Gaura lindheimeri -- also known as White gaura -- which is a herbaceous perennial with a deep tap root.
Gaura may persist as a semi-deciduous plant when winters lack frost or harsh sub-zero temperatures. It usually dies back on some level in winter but resprouts leaves and creates a clump of leaves and stems around a metre tall in spring. Prune off dead or ugly stems and leaves in very early spring, retaining the lower-stem stubs at a length of 5 cm to 16 cm.
The primary pruning maintenance on gaura is deadheading, or the clipping off of flower stems that no longer display blooms. Snip the flowerless stems off at their base near their attachment to main plant stems. Deadheading prevents old flowers' ovaries from producing seeds, thereby encouraging the plant to again produce more flowers in an attempt to create seeds later. Gaura can rebloom repeatedly from late spring through to autumn if deadheading is done often.
Gaura plants that are older and well-established, such as over two years old, may become a large clump of ratty stems. If you wish to prune back the large plant to tidy it up or prevent it from crowding out nearby perennials, clip it back in early spring and again in early summer after the first flowering flush ends. Reduce stem length by 15 to 50 cm, so long as no more than one-half of all stem length is removed. Gaura responds by growing new leaves and branches and then blooming again by midsummer to late summer and continuing until autumn. Deadhead to ensure the best reflowering. Don't rejuvenate-prune the plant past midsummer as the regrowth may not mature enough to rebloom well before winter.
As an alternative to constantly pruning back large clumps of gaura perennials, digging up and dividing plants in the clump reduces individual plant size. This asexual propagation also increases the number of plants that can be grown in locations across the garden. Dig up plants and divide the stems and roots in spring before plants display too many new sprouting leaves.