The Coleus plant (Plectranthus scutellarioides) is celebrated for its vibrant, patterned foliage, adding rich color to gardens and indoor spaces. This plant naturally tends to grow upward quickly, often resulting in long, bare stems with sparse leaves near the bottom. This stretched-out appearance, commonly called “legginess,” concerns growers who prefer a dense, full, and dome-like shape. Addressing this growth habit requires intervention, as the plant will not spontaneously revert to a bushy form. Pruning is the necessary solution to reduce height and encourage the lateral branching that leads to a compact, lush appearance.
Understanding Leggy Growth
The primary cause of a Coleus becoming tall and spindly is etiolation, the plant’s response to insufficient light. When light levels are low, the plant expends energy stretching its internodes—the space between leaf sets—to search for a brighter light source. This results in long, pale, and weak stems that cannot adequately support the plant’s weight.
A second factor is the plant’s internal chemical control system known as apical dominance. This process is governed by the hormone auxin, which is produced in the terminal bud, or main growing tip. The high concentration of auxin suppresses the growth of dormant lateral or axillary buds located further down the stem. This means the plant focuses all its energy on vertical growth, actively preventing the side shoots that would create a fuller appearance from developing.
Step-by-Step Guide to Pruning
Before making any cuts, prepare your tools to prevent introducing pathogens to the plant. Use a pair of small, sharp shears or scissors that have been sanitized with rubbing alcohol or a 10% bleach solution. For young, soft growth, a simple pinch with your clean fingernails is sufficient.
To begin reducing height, identify the correct location for the cut, which is determined by the plant’s anatomy. Stems are segmented by nodes, the points where leaves or leaf buds emerge. The goal of pruning is to remove the active growing tip and the auxin source, stimulating the dormant buds at the nodes below the cut.
For a severely leggy plant, a hard prune is required to dramatically lower the plant’s height. Trace the tall stem down to the point where you want the new growth to begin, and make your cut just above a pair of healthy nodes. Cutting at this point ensures that two new shoots will emerge from the dormant buds, growing outward instead of upward.
A general guideline for hard pruning is to avoid removing more than one-third to one-half of the plant’s total mass at any one time to prevent shock. If the plant is extremely tall, perform the heavy cutting in stages, allowing the plant a few weeks to recover before the next round of shaping. The plant should be actively growing, typically during spring and summer, to recover quickly from any significant cuts.
Maintaining Compact Shape
Once the initial height reduction is complete, maintaining a compact shape requires consistent, regular intervention. This is achieved through a technique called “pinching,” which prevents apical dominance from re-establishing itself. Use your fingers to remove the tiny, newest growth tip and the top set of small leaves on any stem that begins to stretch out.
This simple, frequent pinching redirects the plant’s energy from vertical growth to lateral branching, ensuring the plant stays dense. You should also remove any flower spikes that begin to form. The plant redirects significant energy toward blooming and seed production, which causes the foliage to become sparse and the stem to stretch. Pinching off these flower buds as soon as they appear ensures the energy remains focused on producing colorful leaves.
Post-pruning care is also a factor in long-term success. Since a lack of light is often the root cause of legginess, moving the Coleus to a location that receives brighter, more consistent light will support the new, denser growth. Increased light will naturally encourage a shorter, more robust growth habit. New growth requires energy, so a light application of balanced, water-soluble fertilizer can support the plant’s recovery and the development of new branches.