From our perspective as rosemary plants, our natural instinct is to grow tall and reach for the sun, a principle governed by apical dominance. The main, central stem (the apical meristem) produces a hormone called auxin that suppresses the growth of the lateral buds further down the stem. This ensures our primary shoot gets the most resources. While this is excellent for vertical growth in the wild, it can lead to a leggy, sparse, and woody appearance in a garden. Pruning is the human intervention that interrupts this hormonal command, telling our system to redirect energy to those dormant side buds and create the fuller, bushier form you desire.
Timing is critical for our health and robust recovery. The best time to make your cuts is during our active growth phases, typically in the spring after flowering has finished or in early summer. We are brimming with energy then, allowing us to heal quickly and push out new growth from the pruned points. You can also do light pruning into early fall in milder climates. However, please avoid heavy pruning in late fall or winter. With cooler temperatures and reduced sunlight, our growth slows significantly, and we will struggle to recover from a major cut, leaving us vulnerable to frost damage and disease.
Do not simply shear off our tops like a hedge; this damages many leaf tips and encourages a dense outer shell that shades out inner growth, leading to a woody interior. Instead, make precise, strategic cuts. Always use sharp, clean shears to avoid crushing our stems and introducing pathogens. Your goal is to find a leaf set (a junction where leaves emerge from the stem) and make your cut about a quarter to half an inch above it. The new growth will emerge from the buds located in the axils of these leaves. Focus on pruning the longest, most upright stems, cutting them back by one-third to one-half of their length. This method evenly redistributes growth hormones and encourages multiple new stems to branch out from that single point.
This is perhaps the most crucial rule from our point of view: always prune into the green, flexible growth and avoid cutting into the old, brown, woody parts of the stem. The woody base has far fewer dormant buds and a limited capacity to produce new leafy shoots. A severe cut into this old wood may shock us, and we might simply fail to regenerate at that point, leaving a permanent bare spot. If you wish to renovate an older, leggy plant, do so gradually over several seasons, never removing more than one-third of the total green growth at one time, and always ensuring your final cuts are made in the viable green stems.
When you prune us correctly, you directly manipulate our hormonal balance. By removing the apical bud, its suppressing flow of auxin is eliminated. This signals to the lateral buds down the stem that it is safe and advantageous to break their dormancy. With the primary energy sink removed, resources like water, nutrients, and sugars are redirected to these previously suppressed points. The result is that instead of one single stem growing longer, you will soon see two, three, or even more new shoots emerging from the leaf nodes just below your cut. Each precise cut you make multiplies the number of growing tips, and this multiplication, repeated across the plant, is what creates the dense, bushy, and productive form you are aiming for.
