You CAN cut back lavender.
More Info: Lavender is often grown for its aromatic flowers that appear in shades of white, pink, purple, and blue. While lavender thrives in well-drained soil and full sun, care should be taken when cutting or pruning these plants to avoid injury and insect infestation. These plants are members of the Lamiaceae family and are considered subshrubs, which should be pruned every year after the plant is established.
When to Cut It
Avoid pruning lavender during the cool fall and winter temperatures. These plants do best when cut back or pruned during the spring or after the first bloom of the season. Pruning should be done in the spring when leaves begin to emerge from the plant’s base. Light pruning works best on lavender, as many plants lose their vigor and die after especially heavy pruning. Avoid cutting your lavender all the way down to the ground, as this may cause excess plant stress that may kill your plants. When pruning, remove one-third of the top of the plant to keep plants from splitting.
How to Prune It
Pruning your lavender once each year will keep it healthy and vigorous. Lavender can be harvested when flower buds are 50 percent open and stems should be cut during the early morning hours when oils are heavily concentrated. You can dry lavender in a cool, dry room for use in sachets or in tea.
Fisher, Marty, and Colorado Master Gardener. “Lavender Massed in Xeriscapes.” Colorado State University – Fort Collins. N.p., n.d. Web. 14 June 2012. <http://www.colostate.edu/Depts/CoopExt
Kimbrough, K. A., and C.E. Swift. “Growing Lavender in Colorado.” Colorado State University Extension. N.p., n.d. Web. 14 June 2012. <http://www.ext.colostate.edu/pubs/garden