Skip to Content

7 Reasons Why The Magnolia Tree Is Not Thriving

Magnolia trees can range in height from a towering 5 meters (about 15 feet) to a more modest 2 meters (roughly 6 feet), making them versatile for both standout and complementary planting in your garden. Today, let’s dive into what steps you can take if your magnolia tree isn’t thriving as it should.

When magnolias don’t grow, it could be due to poor soil, incorrect soil pH, pests, too much water, unsuitable climate, or insufficient sunlight. To help your magnolia recover, you should aim for a soil pH between 5.0 and 6.0, enrich the soil with compost and fertilizer, ensure it’s not stuck in dense shade, water it weekly, and use horticultural oil to deal with any pest issues.

Next, I’ll walk you through the signs to watch out for that suggest why your magnolia is struggling, along with detailed steps to address each problem and encourage your magnolia to flourish.

1. Soil pH

magnolia not growing

Magnolia not growing due to high soil pH.

It’s not unusual for soil pH to vary within your garden, affecting magnolia trees differently. You might find one magnolia flourishing in one spot, while another nearby struggles to grow.

If your magnolia isn’t growing well or its leaves are losing their vibrant green color, it could be a sign that the soil’s pH isn’t ideal for magnolias, which thrive in a pH range of 5.5 to 7.0.

Here’s what you can do:

  1. Purchase a soil pH testing kit from a garden store or online to check the soil’s pH level.
  2. If the pH is above 7.0, it’s too alkaline. You can lower it by adding a soil acidifier and organic material to the soil.
  3. If the pH is below 5.0, the soil is too acidic. Increase the pH by adding garden lime.

2. Root Rot

Once a magnolia tree is well-established, it can withstand mild drought conditions without needing extra water. However, during particularly hot spells, a bit of watering can really help them thrive. Overwatering, on the other hand, can lead to waterlogged soil and root rot, as the roots sit in too much moisture.

To tell if overwatering and root rot are problems, look at the tree’s leaves and overall health. Signs like wilted leaves, stunted growth, and leaf discoloration can indicate root rot.

Here’s what you can do:

  1. In its first year, water your magnolia when the top 2 inches of soil feel dry.
  2. Once the tree is established, it’s best to cut back on watering and let it rely on natural rainfall.

3. Light Issues

magnolia not growing

Sunburn

Sunlight is crucial for plants, as it fuels their growth. While some plants thrive in full shade, magnolias are not among them. Depending on the type, magnolias have different sunlight needs. Generally, evergreen magnolias flourish in both full sun and partial shade, but they struggle in areas that are always shaded.

Here’s what you can do:

  1. Evergreen magnolias benefit from being placed in locations with full sun or partial shade.
  2. Deciduous magnolias prefer partial shade and should not be exposed to full sun all day or kept in complete shade.

4. Pests

magnolia not growing

Pest infestation

Insects can pose a real threat to magnolia plants, munching on the stems and leaves and often leaving behind a sticky residue. Mealybugs and scale insects are common culprits. These pests can attach themselves to the plant, draining its vital juices and causing the leaves to turn brown, dry, and crispy. You might also notice a thick, brown crusty substance along the stems and leaf bases. Sometimes, these bugs are visible to the naked eye, gathering in large groups or remaining stationary for their entire adult lives. Thankfully, they’re quite straightforward to manage.

Here’s what you can do:

  1. Use horticultural oil to spray the tree thoroughly.
  2. Plan to repeat the spray treatment after some time to ensure all pests are eliminated.
  3. If certain leaves are heavily damaged, go ahead and trim them off, but try to preserve as much of the plant as possible.

5. Climate

Magnolias are quite resilient and can adapt to a wide range of temperatures, although they don’t fare well in desert-like conditions. However, some magnolia varieties are better equipped to handle temperature extremes than others.

If your magnolia is having a hard time, it might be because the variety isn’t suited to withstand the extreme hot or cold in your area. Signs of heat stress include drooping leaves and new growth with bending stems, while cold stress can cause the leaves’ edges to dry out and become crispy. The Magnolia Society offers a handy guide on which magnolias are best for different hardiness zones.

Here’s what you can do:

  1. In very cold weather, lay down a thick layer of mulch to help keep the roots warm.
  2. During freezing temperatures, consider wrapping the trunk and branches with blankets for extra insulation.
  3. In extreme heat, ensure your magnolia gets plenty of water to prevent stress.
  4. For potted magnolias, move them to full shade during the hottest parts of the day to avoid overheating.

6. Nutrient Deficiencies

Magnolias thrive in nutrient-rich soil, and unfortunately, standard garden or clayey soils often don’t meet their nutritional needs. Such soil conditions can lead to stunted growth, and you might notice the leaves turning dry, crispy, or even yellow, signaling a lack of essential nutrients. Without intervention, these issues can lead to the plant’s demise.

Here’s what you can do:

  1. Enhance the soil by mulching with high-quality compost.
  2. In the spring, apply a multipurpose slow-release fertilizer to support sustained growth.

7. Transplant Shock

magnolia not growing

Transplant shock

Transplant shock is another common reason why magnolias might stop growing. This issue often arises when moving a magnolia from a pot to the ground or relocating it from one spot to another. The transplanting process typically results in some damage to the roots, and the new environment’s differing conditions can stress the plant, potentially halting its growth for a year or even two.

Here’s what you can do:

  1. Provide shade for the plant until the end of the season to protect it from harsh sunlight.
  2. Water the magnolia with moderation, allowing the soil to dry about 1 inch deep between waterings to prevent overwatering.
  3. Hold off on fertilizing and pruning the magnolia while it’s recovering from the shock to avoid adding more stress.