The Mugo Pine, or Pinus mugo, is a popular dwarf conifer widely used in landscaping due to its naturally dense, rounded shape. Although often labeled as slow-growing, this evergreen can eventually exceed the size specified on its nursery tag. To maintain its characteristic compact form and control its size, gardeners must employ a specialized annual pruning technique. This method manages the plant’s seasonal growth, ensuring the Mugo Pine remains a tight shrub.
Pruning Timing and Goals
Pruning a Mugo Pine serves two main purposes: limiting overall size and encouraging denser, more compact foliage. Without annual intervention, the shrub can develop a sparser, more open appearance as its branches lengthen each season. Regular pruning prevents the plant from becoming leggy and helps maintain the thick, bushy habit for which it is prized.
The timing of this pruning is important because pines do not possess dormant buds along their old, woody stems that can sprout new growth. Pruning must be performed exclusively on the current season’s new growth, known as “candles.” The optimal time is late spring or early summer, specifically when the candles have fully elongated and are soft, but before the new needles have fully unfurled. Pruning too early can damage the developing buds, while pruning too late can weaken the plant and result in an unnatural look.
The Candling Technique: Step-by-Step Instructions
The specific pruning method for Mugo Pines is called candling, which targets the upright, light-colored new growth that resembles a wax candle. This new tissue is soft and filled with resin, making it easy to snap or cut. The primary goal of candling is to reduce the length of the new growth, which limits the overall extension of the branch for the year.
To begin, identify the candles at the tip of each branch. Assess the vigor of each candle, noting that those at the top and outer edges of the plant are typically the longest. Generally, you should aim to remove between one-half to two-thirds of the candle’s length. Removing a greater portion results in shorter overall growth, promoting a denser plant.
You can perform candling either by pinching the soft tissue with your thumb and forefinger or by using sharp, clean hand pruners. Pinching is often preferred because the resulting ragged break is believed to stimulate the formation of a cluster of new buds at the cut point. Using pruners provides a cleaner cut, which is acceptable, particularly for thicker candles or when dealing with a large volume of growth.
When shaping the shrub, prune the longest candles on the top and outer parts of the plant more aggressively to maintain the desired shape. Conversely, the shorter, weaker candles found on the interior or lower branches should be pruned less severely, perhaps by only one-third, or left untouched. This selective reduction ensures that energy is redistributed evenly throughout the plant, promoting uniform density and size control.
Protecting Your Pine and Follow-Up Care
The most important rule in Mugo Pine pruning is to never cut into old, hardened, needle-less wood. Pines are unable to regenerate growth from these woody sections. A cut into old wood will result in a permanent, brown stub that will not produce new foliage.
To prevent the introduction of disease, use only sharp and clean tools for any cuts that require shears. This includes the central leader or any candles that are too thick to pinch. Post-pruning care is minimal because the small wounds from candling heal quickly without issue.
After the candling process is complete, a light watering may be beneficial if conditions are dry, helping the plant recover and set its new buds for the following season. The dense, sticky resin released during candling can accumulate on your hands or tools. Clean tools and hands immediately with a solvent like rubbing alcohol to prevent buildup.