Pruning lavender the right way is necessary to maintain the health, vitality, and beauty of this remarkable little herb. Lavender doesn't require a great deal of maintenance, but some attention is needed in the pruning department. The most important thing to remember is to begin pruning lavender while the plant is still young. This way new growth will be encouraged right from the start. It also prevents the stalks from becoming woody in the center, which is a common problem amongst lavender plants that have not been pruned regularly.
Pruning Young Lavender Plants
When the lavender plants are young, and preferably still in pots, simply pinch out any new growth, and cut off the flower heads in the very first year. Although it might seem a strange thing to do, it actually encourages the branches to grow laterally and the flowers and spikes to grow larger the following year. After this, you'll only need to continue pruning lavender plants about once per year throughout their lifespan.
Pruning Lavender after the First Year
Lavender plants should be pruned once per year, after the first year, after they have flowered in the spring or summer. Pruning lavender in the fall is also permissible, as long as it is done well before the first frost. Use hedge trimmers or pruning shears, if possible, to keep things nice and tidy. Prune back about 1/3 of the new growth each time. Pruning lavender any more than this may cause it to wither and die, so use caution. It's better to prune too little than to prune too much. Do not cut all of the new growth down to the stems, as lavender may not survive this type of heavy pruning.
Pruning Old Lavender Plants
Pruning lavender plants that are beyond three years old, or of an indeterminate age, and have never been pruned before is a little trickier. Older lavender plants will not survive heavy pruning, especially if there is more woody growth than new, green growth. If there is new growth visible above the woody stalks, begin by pruning back as much of as possible above the woody areas, without actually cutting into them. This is best performed in the summer time, and only once per year. This technique for pruning lavender will encourage new growth along the entire stem, and may eventually result in a plant that can be reshaped.
In some cases, pruning lavender plants that are aged, and not accustomed to pruning won't do any good, and they may need to be replaced. However, this depends on the type of lavender, and its hardiness and condition. Try pruning lavender for a year or so, and if it doesn't appear to help the plant, consider replacement.
Warning: Never prune old wood from lavender plants unless it is completely dead. Also, pruning lavender until there is no foliage left will most likely kill the plant. Always use caution while pruning lavender to keep your plants as healthy and happy as possible.