Pussy willow is not a single species but a collection of Salix species and cultivars prized for their early spring display. They share the characteristic of producing soft, fuzzy, silvery-gray catkins that emerge in late winter or early spring, often before the leaves. Determining the mature size of a pussy willow is complex because its final dimensions are heavily influenced by two main factors: the inherent genetic potential of the specific species or cultivar planted and the amount of maintenance it receives. This plant can range from a modest garden shrub to a substantial small tree, making species identification and management practices key to understanding its potential size.
The Maximum Potential: Unmanaged Growth
The North American common pussy willow, Salix discolor, represents the maximum potential size when left to grow naturally without human intervention. This fast-growing plant typically develops into a large, multi-stemmed shrub or a small, single-trunked tree. Under ideal conditions, such as full sun and consistently moist soil, its growth is rapid.
The mature height of an unmanaged Salix discolor commonly falls within the range of 15 to 25 feet, occasionally reaching up to 30 feet in favorable environments. The spread is also substantial, often reaching 12 to 20 feet wide, forming a dense, rounded canopy. This size makes the unpruned common pussy willow suitable for large landscapes or naturalizing areas.
Key Varieties and Their Size Profiles
The vast differences in mature size are most evident when comparing the common pussy willow to its cultivated counterparts, which have been bred for smaller spaces. Many popular garden varieties, often derived from the European species Salix caprea, offer significantly reduced size profiles. The weeping pussy willow, Salix caprea ‘Kilmarnock’, is a prime example, commonly grafted onto a straight standard to control its height.
This weeping form usually reaches a total height of only 6 to 10 feet, with a spread of 5 to 7 feet, creating a compact, umbrella-like shape. The limited height is determined by the graft point on the rootstock, as the weeping branches grow down but not up. For the smallest spaces, dwarf varieties like Salix purpurea ‘Nana’ exist, maturing as small shrubs typically only 1 to 3 feet tall. These genetic variations mean that a pussy willow’s size is largely decided at the time of purchase, based on the chosen cultivar.
Managing Size Through Pruning
Even the largest pussy willow species can be maintained at a significantly smaller size through specific pruning techniques. Since the best catkins form on the vigorous new wood produced each year, severe pruning is often practiced to encourage this fresh growth and control the overall dimensions. The most common technique for size control is a method called coppicing.
Coppicing involves cutting all the stems back severely to within 6 to 12 inches of the ground shortly after the catkins fade in the early spring. This action forces the plant to produce numerous long, straight, new shoots during the growing season. The result is a much smaller, dense shrub that is renewed annually, allowing a large species to be kept at a height of 6 feet or less.
Pollarding
A less severe method, known as pollarding, achieves a similar effect by cutting back the annual growth to a permanent, higher framework of main branches. This controlled annual reduction prevents the plant from ever reaching its maximum potential height or spread, accommodating it in smaller garden settings.