Southern Magnolia
Magnolia grandiflora · Big-laurel · Bull-bay · Evergreen MagnoliaUSDA | Grow Zone
7-10Outdoors all year in zones 7 to 10. Anywhere colder, keep it as a houseplant. Protect it below 40°F.
- Light
- Full sun to partial shade
- Water
- Moist soil, weekly deep
- Humidity
- 40-60% humidity
- Temperature
- 60-85°F (15-29°C)
- Difficulty
- Intermediate
- Growth
- Moderate
- Mature size
- 60-80 ft tall
The Southern Magnolia, known for its large, fragrant white flowers and glossy green leaves, is a stunning addition to any landscape. Native to the southeastern United States, this evergreen tree thrives in warm climates and is cherished for its beauty and shade. People grow it for its ornamental value and the delightful scent of its blooms.
Ask Vesper about Southern Magnolia
Ideal temperature
60-85°F is where it grows fastest. Below 40°F cold damage starts.
Spacing and harvest
- Mature size
- 60-80 ft tall
- Plant apart
- 120-240 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Southern Magnolias prefer consistently moist soil, especially during their growing season in spring and summer.
Water deeply once a week, allowing the top inch of soil to dry out between waterings. In winter, reduce watering frequency as the plant enters dormancy. Signs of over-watering include yellowing leaves and root rot, while under-watering can cause leaf drop and wilting.
Light
Southern Magnolias thrive in full sun but can tolerate partial shade.
Ideally, they should receive at least 6 hours of direct sunlight daily. While they can adapt to some shade, insufficient light may lead to leggy growth and fewer blooms.
Soil
These trees prefer well-draining, loamy soil with a pH range of 5.0 to 6.5.
A mix of peat, compost, and sand can provide the necessary drainage and nutrients. Ensure the planting area has good drainage to prevent root rot.
Humidity
Southern Magnolias prefer moderate to high humidity levels, ideally between 40-60%.
To increase humidity, mist the leaves or place a humidifier nearby. Signs of low humidity include browning leaf tips and edges.
Temperature
Ideal temperatures range from 60-85°F (15-29°C).
They are hardy in USDA zones 7-10, tolerating brief cold snaps but may suffer damage in prolonged freezing temperatures. Protect young trees from extreme heat and cold.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10 or similar.
Fertilize in early spring and again in mid-summer, following package instructions for application rates. Signs of nutrient deficiency include yellowing leaves and poor growth.
Pruning
Prune Southern Magnolias in late winter or early spring before new growth begins.
Use sharp, clean pruning shears to remove dead or damaged branches and to shape the tree. Avoid heavy pruning, as it can reduce flowering.
Repotting
Repot young Southern Magnolias every 2-3 years or when root-bound.
Choose a pot 1-2 inches larger in diameter. Signs that repotting is needed include roots growing out of the drainage holes and stunted growth. Carefully remove the plant from its pot, trim any circling roots, and place it in fresh soil.
Propagation
Southern Magnolias can be propagated through semi-hardwood cuttings taken in late summer or by seed.
For cuttings, take 6-8 inch sections, remove lower leaves, and dip in rooting hormone. Plant in a well-draining mix and keep moist until roots develop. Seed propagation requires stratification for 30 days before planting.
When it's unhappy
Yellow leaves
Why it happens
Typically 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.
Leaf drop
Why it happens
Can occur due to stress from drought or sudden temperature changes.
How to fix it
Ensure consistent watering and protect the tree from extreme temperatures.
Root rot
Why it happens
Caused by poor drainage and over-watering.
How to fix it
Improve drainage by amending soil and reduce watering frequency.
Pests (e.g., scale, aphids)
Why it happens
Infestations can occur in stressed plants or during warm months.
How to fix it
Inspect regularly and treat with insecticidal soap or neem oil as needed.
Fungal diseases (e.g., leaf spot)
Why it happens
High humidity and poor air circulation can lead to fungal issues.
How to fix it
Ensure good air circulation and avoid overhead watering to reduce humidity around the foliage.
Care through the year
Spring
In spring, ensure the tree receives adequate water as it begins to leaf out and flower. Fertilize with a balanced fertilizer to support new growth.
Summer
During summer, maintain consistent moisture, especially in hot weather. Monitor for pests and diseases, and water deeply if rainfall is insufficient.
Fall
In fall, reduce watering as the tree prepares for dormancy. Clean up fallen leaves to prevent fungal diseases and prepare for winter.
Winter
In winter, protect young trees from extreme cold and wind. Reduce watering frequency, and avoid fertilizing during this dormant period.
Toxicity & Safety
Southern Magnolia is non-toxic to pets and children. All parts of the plant are safe, making it a great choice for family gardens.
Good to know
How often should I water my Southern Magnolia?
Water your Southern Magnolia deeply once a week during the growing season, allowing the top inch of soil to dry out between waterings.
Why are my Southern Magnolia leaves turning yellow?
Yellow leaves can indicate over-watering or nutrient deficiency. Check the soil moisture and consider fertilizing if necessary.
What type of soil is best for Southern Magnolias?
Southern Magnolias prefer well-draining, loamy soil with a pH range of 5.0 to 6.5. A mix of peat, compost, and sand works well.
When is the best time to prune my Southern Magnolia?
Prune your Southern Magnolia in late winter or early spring before new growth begins to maintain its shape and remove any dead branches.
Can Southern Magnolias tolerate cold weather?
Southern Magnolias are hardy in USDA zones 7-10 and can tolerate brief cold snaps, but young trees should be protected from prolonged freezing temperatures.
How do I propagate Southern Magnolias?
Southern Magnolias can be propagated through semi-hardwood cuttings in late summer or by seed, which requires stratification before planting.
What are the signs of root rot in Southern Magnolias?
Signs of root rot include yellowing leaves, wilting, and a foul smell from the soil. Ensure proper drainage and adjust watering to prevent this issue.
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