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.
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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
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.
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.
Ants
Ants – and in most cases Argentine ants – are a very common pest that can cause a lot of damage to Ceanothus plants If they are not dealt with.
Ants can be hard to notice at first, and common signs include ants at the base of the plant, ant nests a few feet away from the base of the plant, and ants crawling up the stem of the plant.
Ants may also remove soil around the roots to promote scale, which then leaves behind honeydew for the ants to feed on.
How To Deal With Ants On Ceanothus
Treatment for ants involves spraying with synthetic pyrethroid or pyrethrin.
There are a lot of steps involved, and the process is quite complicated, so I recommend reading through this guide by the CNPSSD for full details.
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.
That’s very helpful. I will try to figure it out based on your descriptions.
It is certainly stressful especially since it happened suddenly. The plants around seem fine so I’m mystified.
My ceanothus died suddenly this season, after 10+ years of thriving. I can’t see how temperature or watering could be a factor. The notable thing though is that for the first time ever I pruned it a couple of months before. Perhaps it was in fact “poor pruning.” I say it died, but a single healthy healthy-looking cluster of leaves at the extreme end of one branch has recently appeared, so we’ll see.
Hi David,
After that amount of time, factors like temperature or watering shouldn’t be an issue assuming you didn’t change anything.
Pruning can kill ceanothus, but they usually are quite hardy, even if you accidentally remove too much. I’d recommend reading this resource from the RHS – https://www.rhs.org.uk/plants/ceanothus/growing-guide – as different types of ceanothus should be pruned differently, and this summarises it well.
As there is new growth your ceanothus will likely be fine, and it may just be recovering from over-pruning. Good luck!
Thanks Joe. I see this in your link: “Evergreen Ceanothus generally do not respond well to hard pruning into older wood, so it is better to replace overgrown plants than to try renovation.” I did not really do much cutting, but it was the first time I had done any at all. The variety I have (c.cyaneus) is native to my area, and basically it had taken care of itself very well without me doing much of anything, so that’s why I don’t think temperature and water are an issue. Three or four more random leaves have sprouted, so I’m not giving up yet.
I live in San Diego, California near the coast and have two Ceanothus (“Sierra Blue”) that I planted four years ago. Both are about 6′ tall now. We’ve had record rain this winter and spring so no supplemental watering for at least the past six months. I’ve also never pruned them. They are planted 15′ apart among native salvias and buckwheat. Both were doing spectacular and had growth spurts and copious blooms. However, while one still looks great, the other ‘s leaves are yellowing and new growth is small and pale. It was a lustrous, dark green a month ago but looks very poorly now. Any suggestions?
Hi Rebecca, thanks for getting in touch!
That does sounds like quite an odd case.
Clearly both plants have had the same amount of water and sunlight, so we can rule those out. As both have been growing happily for 4 years we can also rule out an issue with where you bought them from, such as one of the plants being root bound or in worse condition to start off with.
Given the size of both Ceanothus’ it’s also not due to old age either as both have not fully grown
Usually in cases like this it is due to pests or a disease that is affecting one plant and not the other, so the first thing you need to do is look at the plant that is struggling closely for any signs of pests or diseases. This could be unlikely due to how close they are planted together, but it’s worth ruling it out as these will spread quickly.
Aside from that, are there any other differences you could think of between the two plants and how they have been cared for?
Thank you for your response. I am also thinking something perhaps at the root level and targeted on this plant alone. Every leaf and blossom on it is shriveled now and its trunk and branches have a whitish cast to them. Such a mystery!
Help my bush is about 3/4 years old about 6foot high. It’s been looking very healthy green shining leaves. Its never flowered, but this year we have lots of buds but they are brown in colour and not flowering. Help whats happen.
Hi Patricia!
Ceanothus can sometimes be tricky to get to flower, and I’ve known a few that have never flowered at all.
In your case, since there are buds it is clearly making an attempt to bloom. To encourage this, I would recommend using a fertilizer that ideally contains more Phosphorus than Nitrogen, as Phosphorus will encourage blooming while Nitrogen tends to promote better leaf growth.
If you don’t get any flowers this time around there is still hope. Continue fertilizing throughout the summer and prune to encourage new growth.
This guide will give you a good idea for pruning – https://www.rhs.org.uk/plants/ceanothus/growing-guide. Also make sure that your plant is receiving enough sunlight, as you tend to get better blooms with more full sun hours.
I once had 8 healthy mature ceanothus (different varieties) in my garden and they suddenly started dying off one by one, over a period of 12 years. It turned out the problem was ANTS! https://www.cnpssd.org/s/General-statement-on-Ants-Rev-3-4-22.pdf After the ceanothus, the ants started attacking other plants in the garden. I’ve since been able to save 2 of my Toyons following the instructions in the CNPSSD PDF.
Hi Renee,
Thanks for sharing that information, I’m going to read through that PDF and add it into the article – fascinating stuff!
Our well-established Ray Hartman ceanothus of 8 years is suddenly drying up! We live in Long Beach, CA and loved this plant because it was so drought tolerant and maintenance free. Previous summers I would spray a little water in its direction once a month and we had such a wet winter that I thought it would be fine but leaves are brown, dry and it’s spreading fast. We deep watered it this week to see if that helps but I don’t think it typically makes new growth this time of year. I am just so heartbroken over this tree. We get so many compliments on it and my kids (and bees and humming birds) love it’s flowers. Do you think because it’s so dry we should deep water it weekly or will that lead to overwatering?
Hi Marina,
It’s a tricky one because there’s a chance it was overwatered during the winter, which could have resulted in root damage. Did the leaves turn yellow quickly rather than brown during or after the winter? If so, that’s a classic sign of overwatering.
If the roots have rotten due to that, watering more now won’t help matters as the roots won’t be absorbing water like usual.
On the other hand, if its underwatering throughout the year this would have made the leaves go brown quickly rather than yellow. My advice would be, if possible, to inspect the roots for damage.
If they are healthy, continue watering slightly more than usual and you should see a return to health. If they are damaged or rotten, remove the affected sections and treat the rest with a fungicide.
Sorry for the complicated answer, but this issue is a bit more complex!