Goat willow (Salix caprea) is a small deciduous tree or large shrub also known as pussy willow. Goat willow is native to Europe and western and central Asia. This species is not considered a good source of timber, as its wood is brittle. Salix caprea means “goat.” This species is susceptible to disease mediated by insects and microbes.
I. Appearance and Characteristics
Salix caprea, known as goat willow, pussy willow or great sallow, is a common species of willow native to Europe and western and central Asia.
The Latin specific epithet caprea means “goat”. This, and the common name goat willow, probably derive from the first known illustration of the species in Hieronymus Bock’s 1546 Herbal, where the plant is shown being browsed by a goat. The species was historically also widely used as a browse for goats, to which Bock’s illustration may refer.
It is a deciduous shrub or small tree, reaching a height of 8–10 m (26–33 ft), rarely to 13 m.
The leaves are 3–12 cm long and from 2–8 cm wide, broader than most other willows.
The flowers are soft silky, and silvery 3-7-cm-long catkins are produced in early spring before the new leaves appear; the male and female catkins are on different plants (dioecious). The male catkins mature yellow at pollen release, the female catkins mature pale green.
The fruit is a small capsule 5–10 mm long containing numerous minute seeds embedded in fine, cottony hairs. The seeds are very small (about 0.2 mm) with the fine hairs aiding dispersal; they require bare soil to germinate.
The two varieties are:
- S. c. var. caprea – lowland regions throughout the range, leaves thinly hairy above, densely hairy below, 5–12 cm long, stipules persistent until autumn
- S. c. var. sphacelata (Sm.) Wahlenb. (syn. S. caprea var. coaetanea Hartm.; S. coaetanea (Hartm.) Floderus) – high altitudes in the mountains of central and northern Europe (Alps, Carpathians, Scotland, Scandinavia), leaves densely silky-hairy on both sides, 3–7 cm long, stipules early deciduous. In western Norway there are trees of S. c. var ‘Sphacelata’ that are 18–20 meters tall and have mostly single trunks.
S. caprea occurs both in wet/damp environments, such as riverbanks and lake shores, and in drier sites, wherever bare soil becomes available due to ground disturbance.
Hybrids with several other willow species are common, notably with Salix cinerea (S. × reichardtii), Salix aurita (S. × multinervis), Salix viminalis (S. × smithiana), and Salix purpurea (S. × sordida). Populations of S. caprea often show hybrid introgression.
Unlike almost all other willows, pure specimens do not take root readily from cuttings; if a willow resembling the species does root easily, it is probably a hybrid with another species of willow.
The leaves are used as a food resource by several species of Lepidoptera, and are also commonly eaten by browsing mammals. Willows are very susceptible to gall inducers, and the midge Rhabdophaga rosaria forms the camellia gall on S. caprea.
II. How to Grow and Care
Sunlight
This tree prefers to receive plenty of sun (six-plus hours each day), although it can tolerate a partial shade position.
Temperature and Humidity
Hardy in USDA zones 4 to 8, this plant prefers a temperate, mild summer and can handle cold winters with ease. Extreme and prolonged freezing conditions can cause branches to weaken and crack, but the damage is easily pruned out and doesn’t cause lasting damage to the plant. In very hot regions, the growth rate of goat willow is usually considerably slower. Humid conditions may make goat willow somewhat more prone to fungal diseases.
Watering
Goat willow is a water lover, thriving in areas that have moist, even wet conditions. It does well in wetlands and bogs and is a great choice for gardens that have poor drainage. Goat willow is also relatively tolerant of short droughts, though growth can be stunted under these conditions
Soil
Goat willow will grow in most soil types but has a preference for damp soil. It is one of those few species that actually prefers dense, poorly drained soil. It can tolerate dry and sandy conditions too, although mulching around the base of the tree can be beneficial in these situations.
Fertilizing
Unless you’re growing goat willow in a container, you won’t need to fertilize the plant. Its spreading roots help it to find the nourishment it needs. One exception is if you want to grow the plant for the purpose of harvesting the young stems in the spring when they are covered with catkins. If this is your goal, it’s best to cut the plant down to ground level and fertilize heavily each spring.
Planting Instructions
Pruning
Goat willow can be coppiced (trimmed off at ground level) without any problem. Cutting them right back to the ground every few years can stimulate good regrowth and usually results in larger catkins and longer stems developing. This tolerance for frequent hard pruning makes goat willow a viable plant for hedges. If you plan to trim the tree, make sure you do this immediately after the blooming season. The catkins form on the previous season’s wood, and you don’t want to risk diminishing next year’s display by pruning too late.
Propagation
While most species of willows are extremely easy to propagate simply by planting a branch cutting directly in the soil, goat willow is slightly more temperamental as regards this method, and therefore is more often propagated by seeds (see below).
Rooting stem cuttings can be successful, but you may need to plant several cuttings to ensure success with at least one. Here’s how:
- During active growth in spring, cut a new, reasonably thick branch that has at least a couple of buds higher up on the cutting.
- Dip the cutting in rooting hormone, and plant it about 6 inches deep in the desired garden location.
- Keep the cutting well watered. Within a few weeks, the cutting may develop rots and begin producing new growth.
- You can use the same technique to start cuttings in containers filled with potting mix.
How to Grow From Seed
Goat willow is a dioecious plant, with plants having either male or female catkins, but not both. Therefore, if you want fertile seeds, you’ll need to have a female plant as well as a male plant somewhere in the near vicinity.
In mid-spring when the catkins have a cottony appearance, harvest some catkins from a female plant (these catkins will have a greenish color) and break them apart to separate the seeds. Immediately sow the seeds on the surface of small containers or a seedling flat filled with standard potting mix, with the silky seed hairs still attached. Keep the seeds likely moist until they germinate and sprout. The seedlings grow very quickly, so they can be transplanted into their permanent garden locations within a few weeks.
Do not attempt to store goat willow seeds, as they will quickly lose their viability if not planted immediately.
Potting and Repotting
Goat willow grows fast and gets large rather quickly, so it’s not often grown in containers, except for starting stem cuttings. The weeping variety (Salix caprea ‘Pendula’) is a somewhat smaller plant, however, so it is sometimes grown in large, deep, heavy pots that can resist tipping. A potted goat willow will need an extremely moisture-retentive potting mix, such as a mixture of commercial potting mix blended with compost. Be prepared to water potted willows very frequently. A potted goat willow may also benefit from a fertilizer applied annually in the spring.
Overwintering
Goat willows grown as garden specimens generally don’t require any special winter treatment. If you are growing one as a potted plant, however, it will need some protection against the cold. Moving it to an unheated garage or porch is a good method. Or, the pot can be moved to a sheltered location and wrapped with insulation or heaped with compost for the winter.
Pests and Diseases
Common Pests and Plant Diseases
Although the tree is hardy, goat willow is susceptible to several diseases, including powdery mildew, twig and leaf blight, and leaf spot. Willow anthracnose is a more serious fungal disease that can cause complete defoliation of the plant after initially causing black spots and distorted growth. It is a hard disease to cure, but removing affected branches and cleaning up leaf debris can keep anthracnose from spreading to the entire plant.
Aphids and caterpillars are drawn to the leaves of this plant. Hard water spray will dislodge these pests; or, you can spray the plant with horticultural oil.
Common Problems
Goat willow is very easy to grow, but the wood is brittle and subject to breakage from heavy snows or ice storms. Fortunately, damaged branches are easily cut out, and heavy pruning only stimulates new growth.
In its eagerness to reach moisture, the roots of goat willow have been known to damage underground water pipes or sewer lines and can clog drain lines. It is best planted many feet away from such utilities.
III. Uses and Benefits
The silky, grey-colored catkins that are produced in the spring by goat willow have long been admired, with this tree planted for ornamental purposes in parks, woodland areas, and wildlife gardens. This tree will flourish in moist ground, tolerating saturated soil, so planting alongside ponds and streams is not an issue. It is prized for being low maintenance and is excellent as a windbreaker or screen.
