Ceanothus Dying Suddenly? Most Common Reasons

The Ceanothus is known for its beautiful blue flowers that appear in late spring or early summer. It’s easy to grow, making it great if you are a beginner or a laiz faire gardener, which makes a Ceanothus dying suddenly quite the stressful situation.

Even though it’s easy to care for, it is susceptible to a few problems. The most common causes of problems with the Ceanothus include root rot, frost damage, or canker disease. 

Ceanothus Basics

The Ceanothus is part of the buckthorn family. They are shrubs and small trees, depending on the variety. Other names for the Ceanothus include Buckbrush and California Lilac. 

Most Ceanothus species produce blue blooms, but some varieties produce white or pink blooms instead. Some varieties, including Ceanothus americanus, or New Jersey Tea, will thrive in zones 4-8. Most species do well in zones 7-9

As the Ceanothus matures, it becomes very drought tolerant. Most species prefer full sun, but they can also tolerate partial shade. In areas with very bright hot afternoon sun, partial shade may be preferable. 

Frost Damage 

If your Ceanothus is dying during the winter months, it may be frost damage. Frost damage will affect new growth first. The new leaves and stems will turn brown. 

If frost damage continues, it can spread to other areas of the plant. The bark may begin to crack as well. 

Can You Save a Frost Damaged Ceanothus?

The Ceanothus will recover from mild frost damage, similarly to other plants such as Weigela. To determine the extent of the damage, check underneath the bark. If you see green beneath the bark, the Ceanothus will be fine. 

If you see no green under the bark, the plant will likely not survive. 


Overwatering your Ceanothus can actually kill it. It’s known as the California Lilac because it thrives in the California climate, which is very dry. 

The first signs of overwatering are yellow leaves and wilting. This can cause confusion because these can also be the signs of underwatering. 

However, the Ceanothus requires very little watering, so it’s safe to assume that too much water is the culprit. 

Distinguishing Between Over And Under Watering 

You can check the soil for moisture. If the soil is very moist, or you’ve been watering frequently, overwatering is probably the problem. Even if the soil is dry, it doesn’t mean the plant is being underwatered. The plant needs periods of dry soil. 

The best way to determine if your Ceanothus is over or under watered is to look at the leaves. Both will cause leaves to turn yellow. However, overwatering will cause the leaves to wilt. 

If the Ceanothus isn’t receiving enough water, the leaves will feel very dry. 

A flowering Ceanothus

How to Water the Ceanothus

If your Ceanothus is dying because of improper watering, you can fix the problem by watering properly. Water the plant deeply once a month during the summer. 

The Ceanothus doesn’t typically need water at other times of the year. Naturally, occurring rain should provide all the water that your plant needs. 

Soil Drainage 

For your Ceanothus to thrive, it must be in the correct soil. The plant actually grows well in what is typically considered poor soil. However, it must be well-draining. 

Soil with a high clay content will be problematic for the Ceanothus. You can amend the soil with sand to improve drainage. You’ll need to avoid adding any moisture-retaining material, including compost and mulch. 

Lastly, position your plants appropriately. Water should run away from the plant, not towards it. It’s unwise to plant the Ceanothus at the bottom of a hill, or near sprinkler systems. 

Root Rot 

Overwatering will often lead to root rot. Overwatering itself can be reversed by changing your watering practices. However, root rot is more problematic and affects a wide variety of plants like Calathea and Majesty Palms.

Consistently wet soil is a perfect breeding ground for the fungi that causes root rot. Once the fungus begins to grow, it will cause the roots to rot. 

Over time, the roots will become brown and mushy. They can no longer bring in the water and nutrients the plant needs. 

Signs of Root Rot 

In addition to the signs of overwatering, root rot will stunt the plants’ growth. The Ceanothus may begin to die off as root rot progresses. You may also notice ammonia or sewage smells. This comes from the decomposing roots. 

Unfortunately, the disease can spread through the soil. If you have an infected plant, removing it is important. 

Treating Root Rot 

Prevention of root rot is the best course of action. Along with proper drainage and watering, fungicides can be used to prevent root rot from developing. They can also delay or stop the growth while the fungicide is active. However, they are not a cure for an active case of root rot. 

Once root rot occurs, the only way to save the plant is to remove it from the soil. Mild cases can be treated by cutting away any infected roots. 

Then, you’ll need to apply a fungicide to the roots before replanting. Replant in new soil, preferably in a new area. 

Plants near the affected plant should be replanted in a new area as well. Check the roots for signs of root rot before replanting. 

Canker Disease 

Canker disease can occur due to bacteria or fungus. It affects woody plants and shrubs, including the Ceanothus. The cankers form on areas of the plant that have been previously injured. 

This can include poor pruning, mechanical injury, or sunburn. The wounds on the plant allow an opening for the bacteria or fungus to enter. 

The lesions are brown. If you cut a lesion, you will see dead tissue. The bacteria will spread to other areas.

Unfortunately, this can kill a Ceanothus fairly quickly. 

Treating Canker Disease 

There’s no chemical treatment for canker disease. Instead, you’ll need to focus on management. Trim any affected areas of the Ceanothus immediately. 

To prevent Canker disease, keep the Ceanothus as healthy as possible. Healthy plants are much less susceptible to diseases, including Canker disease. 

Final Thoughts on Ceanothus Dying Suddenly 

The cause of death for a Ceanothus is typically root rot due to overwatering. Canker disease can also kill your plants. Underwatering will cause your Ceanothus to have issues as well but is less common and easier to treat than other causes. 

Photo of author

About Me

Hi, I'm Joe! I'm the head of SEO and content management at Bloom and Bumble. I'm a huge plant lover and over the years my home has become more like an indoor rainforest. It has taken a lot of trial and error to keep my plants healthy and so I'm here to share my knowledge to the rest of the world.

Leave a Comment