A cultivar of Winterberry, common winterberry ‘Winter Red’ is considered among the most desirable winterberries because this cultivar produces an unusual abundance of bright red fruits. The berries appear from autumn throughout winter, enlivening the landscape when much else is withered. This cultivar has been awarded an Award of Garden Merit by the UK’s Royal Horticultural Society.
I. Appearance and Characteristics
Valued for its heavy fruit set and persistence, Ilex verticillata ‘Winter Red’ is widely regarded as one of the best winterberries. Slow-growing, this multi-stemmed, deciduous winterberry holly features a shapely oval form and produces abundant small greenish-white flowers in late spring or early summer. They are followed by a profusion of magnificent cherry red berries from fall through winter. Extremely attractive, they enliven the winter landscape and often persist into early spring unless eaten by birds. The foliage of lustrous, leathery, dark green leaves does not develop any appreciable fall color.
‘Winter Red’ is a female plant and needs a male pollinator to produce attractive bright red berries. Generally, one male winterberry will be sufficient for pollinating 9-10 female plants. Since the blooms come late, ‘Winter Red’ requires a late-blooming male as a pollinator (such as ‘Southern Gentleman’ or ‘Apollo’).
II. How to Grow and Care
Sunlight
Common winterberry ‘Winter Red’ requires an environment with bright and soft light to grow. It grows well in shady places, sheltered on one side, and even in direct sunlight. Mature plants have higher fruit growth rates in places with good light. Young plants, on the other hand, need a shady place (shade cloth can be used) in summer to avoid direct sunlight and prevent sunburn.
Common winterberry ‘Winter Red’ kept indoors should be placed in sunny rooms, about 50 to 100 cm from the window. Do not place the plant in an environment where light is completely blocked. After extended periods of insufficient light, the plant’s photosynthetic rate will decrease. This will slow down the growth rate possibly to zero, cause thin and weak leaves, and decrease the flowering and fruiting rate.
Temperature
Common winterberry ‘Winter Red’ is distributed in tropical, subtropical, and temperate regions. It thrives in a cool and humid environment. It grows in temperatures ranging from 10 to 31 ℃, is relatively cold-resistant, and can safely overwinter outdoors at about -3 ℃. It grows well at a relative air humidity of 70%, suggesting that arid environments should be avoided.
Watering
Common winterberry ‘Winter Red’ grows in humid environments and is not resistant to drought. Keep the soil moist during spring and summer. If rainfall is less than 2.5 cm per week when cultivated outdoors, manual watering is required. Water once a day and ensure that the soil around the root system is completely wet. Surplus water should drain away smoothly without accumulating. Spray mist during the day to increase air humidity, which is preferably kept at 70%-90%. After the fruiting period in winter is over, gradually reduce the watering frequency to once a week, and completely drench the soil only if it is completely dry.
It is best to water common winterberry ‘Winter Red’ in the morning and evening because the temperature around the root system tends to rise if it is done at noon, especially in summer. This will cause damage to the plant. Use rainwater and distilled water rather than tap water, which contains a large amount of calcium and magnesium mineral salts. Long-term use of tap water will cause salinization, hardening, and poor permeability of the soil as well as affect plant growth and ornamental effect. Inadequate or excessive water will both cause the leaves to turn yellow and shed.
Soil
Common winterberry ‘Winter Red’ likes acidic soil with a pH value of 5-6. In neutral or alkaline soil, its leaves tend to yellow and the plant may even die. It requires humid culture media that retain water and are rich in organic matter. Humus soil with an appropriate amount of coarse sand or perlite added will increase soil permeability. A formula for the culture medium, for example, could be 1/2 leaf mold + 1/4 coarse sand or perlite + 1/4 decomposed bark.
Before putting it into the pot, the medium should be soaked in a carbendazim solution to kill any bacteria and insect eggs. Some ceramsites can be put at the bottom of the pot to improve drainage and avoid water accumulation caused by excessive daily watering. Change the soil every two years.
Fertilizing
Common winterberry ‘Winter Red’ does not require much fertilizer. Apply some fertilizer during the growing season to promote luxuriant branches and glossy leaves. Apply thin fertilizer once in early spring and once in early autumn. Compound fertilizer mainly composed of nitrogen fertilizer can make the leaves brighter and bigger.
Stop fertilizing when the temperature is higher than 30 ℃ in summer to prevent root damage. Insufficient fertilization can cause thin and weak plants, sparse fruits, and thin and dull leaves. Large but dull leaves may be caused by over-fertilization and signal that fertilization should be stopped immediately.
Planting Instructions
Thought its red fruits are a Christmas symbol, it is generally best to plant common winterberry ‘Winter Red’ in spring. Large seedlings over 2 years old are preferred for planting. Plants should be spaced about 1 m apart and there should be about 1 to 1.2 m between rows. Compacting the soil and watering after planting will allow the roots to be in closer contact with the soil. It should be noted that common winterberry ‘Winter Red’ is dioecious, so it requires both female and male plants present to produce fruits. Successful pollination only happens when plants are spaced no more than 9 m apart. One male plant can pollinate 6-10 female plants.
Pruning
Common winterberry ‘Winter Red’ flowers and fruits only grow on new branches, so the plant needs to be pruned to promote the germination of new branches. It’s best to prune before early spring, ideally during winter. In addition to promptly cutting off old, yellow, dried, and diseased leaves, one-third of the old branches should be cut off from the base every year. This promotes vertical growth, flowering, and fruiting. After winter pruning in cold areas where it snows, the remaining branches can be bundled with ropes to avoid damage caused by snow or ice on the branches.
Transplanting
Common winterberry ‘Winter Red’ thrives when transplanted in early or mid-spring due to its dormancy period. Ensure it’s placed in a location with moist, acidic soil and partial to full sun. Avoid transplanting in late fall or early winter to reduce stress.
III. Uses and Benefits
Mass in mixed shrub borders. Perfect as a specimen plant, hedges, or for foundation plantings. Excellent shrub for wet soils, bog gardens, rain gardens, and along streams or ponds. The red-fruited branches make lovely home decorations
IV. Harvesting and Storage
In suitable growth conditions, common winterberry ‘Winter Red’ blooms and bears fruits once a year. The fruits appear in fall and winter, and can be appreciated for a long time before picking. Without birds in the yard, the fruits often persist into the next spring. The vase life of fruit-bearing branches after picking is about 20-40 days.
Use sharp garden shears when picking and cut the base of branches at a 45-degree angle, or make the cut into a cross, to increase the water absorption area. Quickly put the cutting in a vase with clean water to avoid water loss. The fruits of Ilex verticillata can also be air-dried since they tend to not drop from the branches. Their colors will change from bright red to deep red, providing good ornamental value.
