Common Winterberry
Ilex verticillata · Black Alder · Coralberry · Michigan Holly · WinterberryUSDA | Grow Zone
3-9Outdoors all year in zones 3 to 9. Anywhere colder, keep it as a houseplant. Protect it below 0°F.
- Light
- Full sun to partial shade
- Water
- Deeply once a week
- Humidity
- 40-60%
- Temperature
- 20-85°F
- Difficulty
- Intermediate
- Growth
- Moderate
- Mature size
- 6-10 ft tall
Ilex verticillata, commonly known as Winterberry, is a deciduous holly native to North America. Its vibrant red berries attract birds and add winter interest to gardens, making it a popular choice for landscaping.
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Ideal temperature
20-85°F is where it grows fastest. Below 0°F cold damage starts.
Spacing and harvest
- Mature size
- 6-10 ft tall
- Plant apart
- 48-72 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Ilex verticillata prefers consistently moist soil, especially during the growing season.
Water deeply once a week, allowing the top inch of soil to dry out between waterings. In hot weather, you may need to increase frequency. Signs of over-watering include yellowing leaves and root rot, while under-watering can cause wilting and leaf drop.
Light
This plant thrives in full sun to partial shade, ideally receiving 6-8 hours of sunlight daily.
It can tolerate some shade but may produce fewer berries. Ensure it is placed where it can receive morning sunlight for optimal growth.
Soil
Ilex verticillata prefers acidic, well-draining soil with a pH range of 5.0 to 6.5.
A mix of peat moss, pine bark, and perlite is recommended for potting. Good drainage is essential to prevent root rot.
Humidity
This plant prefers moderate humidity levels, around 40-60%.
To increase humidity, mist the leaves or place a humidifier nearby. Signs of low humidity stress include brown leaf tips and edges.
Temperature
The ideal temperature range for Ilex verticillata is 20-85°F (-6 to 29°C).
It is hardy in USDA zones 3-9 and can tolerate cold temperatures but may suffer in extreme heat. During winter, protect the roots with mulch to prevent freeze damage.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10, applying it in early spring before new growth begins.
Fertilize every 4-6 weeks during the growing season. Signs of nutrient deficiency include stunted growth and yellowing leaves.
Pruning
Prune Ilex verticillata in late winter or early spring before new growth starts.
Use sharp, clean pruning shears to remove dead or damaged branches and to shape the plant. Deadheading is not necessary, but removing spent flowers can encourage new growth.
Repotting
Repot Ilex verticillata every 2-3 years or when it outgrows its pot.
Choose a pot that is 1-2 inches larger in diameter. Signs it needs repotting include roots growing out of the drainage holes and stunted growth. Carefully remove the plant, refresh the soil, and place it in the new pot.
Propagation
Ilex verticillata can be propagated through softwood cuttings taken in late spring or by seed.
For cuttings, select healthy stems, cut them to 4-6 inches, and place them in a moist potting mix. Seeds should be stratified for 30 days before planting in spring.
When it's unhappy
Yellow leaves
Why it happens
This can be caused by over-watering or nutrient deficiency.
How to fix it
Check soil moisture levels and adjust watering accordingly. Fertilize if nutrient deficiency is suspected.
Root rot
Why it happens
Over-watering or poorly draining soil can lead to root rot.
How to fix it
Ensure proper drainage and reduce watering frequency. If root rot is present, remove affected roots and repot in fresh soil.
Leaf drop
Why it happens
Leaf drop can occur due to stress from drought or sudden temperature changes.
How to fix it
Maintain consistent watering and protect the plant from extreme temperature fluctuations.
Poor berry production
Why it happens
Insufficient pollination or lack of male plants nearby.
How to fix it
Plant a male Ilex verticillata nearby to ensure cross-pollination for better berry production.
Pests (aphids, spider mites)
Why it happens
Pests can infest the plant, especially in dry conditions.
How to fix it
Inspect regularly and treat infestations with insecticidal soap or neem oil.
Care through the year
Spring
In spring, prune any dead or damaged branches and apply a balanced fertilizer to promote new growth. Ensure consistent watering as temperatures rise.
Summer
During summer, monitor soil moisture closely, especially during dry spells. Mulch around the base to retain moisture and suppress weeds.
Fall
In fall, reduce watering as the plant prepares for dormancy. Mulch around the roots to protect them from freezing temperatures.
Winter
In winter, protect the roots with mulch and ensure the plant is not exposed to harsh winds. Water sparingly if the soil is dry.
Toxicity & Safety
Ilex verticillata is considered non-toxic to pets and children. However, ingestion of large quantities of berries may cause mild gastrointestinal distress. The leaves and stems can be mildly toxic if consumed.
Good to know
How often should I water my Ilex verticillata?
Water your Ilex verticillata once a week, ensuring the soil remains consistently moist but not soggy. Adjust frequency based on weather conditions.
What type of soil is best for Winterberry?
Winterberry thrives in acidic, well-draining soil with a pH of 5.0 to 6.5. A mix of peat moss, pine bark, and perlite is ideal.
Why are my Winterberry leaves turning yellow?
Yellow leaves can indicate over-watering or nutrient deficiency. Check soil moisture and consider fertilizing if needed.
When should I prune my Ilex verticillata?
Prune your Winterberry in late winter or early spring before new growth begins to maintain shape and remove any dead branches.
Can I propagate Ilex verticillata from cuttings?
Yes, you can propagate Winterberry from softwood cuttings taken in late spring. Ensure to place cuttings in a moist potting mix for best results.
What are the ideal light conditions for Ilex verticillata?
Ilex verticillata prefers full sun to partial shade, ideally receiving 6-8 hours of sunlight daily for optimal growth and berry production.
Is Ilex verticillata toxic to pets?
Ilex verticillata is non-toxic to pets and children, but ingestion of large quantities of berries may cause mild gastrointestinal distress.
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