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Hinoki cypress trees are a statement in any garden. Therefore, you may be worried if you noticed that, even though it’s supposed to be an evergreen tree with luscious green leaves, it’s starting to turn brown. What causes this, and is it a problem?
The most common cause of a hinoki cypress tree turning brown include disease-causing pathogens, sun scortch, overwatering, and excessive wind exposure.
In this article, I’ll explore everything you need to know about why your hinoki cypress tree is turning brown and what you can do to make it healthy again.
1. Your Hinoki Cypress Tree Is Diseased
Although your hinoki cypress’ needles could be turning brown because this is a natural part of the tree’s growth, it could also be targeted by fungal blight disease. This plant disease is caused by pathogens that thrive in moist and cool weather conditions.
Symptoms of this disease include the following:
- The tree’s needle tips start turning brown.
- Cankers appear on twigs that eventually lead to tree dieback. Cankers are symptoms that the plant has been injured and infected with a bacterial or fungal pathogen.
How To Fix
To stop this fungal disease from spreading, you should do the following:
- Cut away any dead tissue on the tree. You should cut approximately two inches (5.08 cm) into the tree’s healthy tissue.
- Encourage dry conditions to prevent recurrent infections. Fungal diseases are common in very moist, damp environments.
2. Your Hinoki Cypress Tree Is Sun Scorched
Although your cypress tree wants to be planted in an area where it will get full sun for a minimum of six hours per day, it’s not good for the tree to be in an area of direct sun, especially if it’s exposed to harsh afternoon sun, as this can cause sun scorch (source).
You can tell that your cypress tree is being burned by the sun if it displays symptoms such as:
- Brown or purple discoloration of needle tips (source).
- Yellowing of leaves.
- Severe browning of needles.
How To Fix
Unfortunately, once your plant leaves have experienced sun scorch, they won’t recover. They have to be removed. Therefore, it’s best to care for the tree to prevent sun scorch from happening in the first place. This can be achieved in various ways, such as:
- Protecting your cypress from the harsh afternoon sun. This could include shielding it with a larger tree or some other sort of shading.
- Placing two inches (5.08cm) of mulch around the base. This will encourage cool, moist soil for the tree so that it will reduce the temperature to which it’s exposed, preventing heat stress.
- Wrapping the trunk. To reduce and prevent the risk of sun scorch, you can wrap the tree’s trunk with paper. I’d recommend the Asdomo Tree Protector Wrap, (link to Amazon). It blocks the sun’s harmful rays but is breathable, as it’s made out of thermal insulation material.
3. You’re Overwatering Your Hinoki Cypress Tree
Although your cypress tree wants to be watered once a week for a full year after being planted in the garden, you need to scale back on how much you water it to prevent issues.
When your hinoki cypress gets too much water, this can cause more than discolored foliage. It puts the tree at risk of experiencing stunted growth as a result of root rot, which can be fatal to the plant as it destroys the root systems of the tree. See our guide to The Signs Of Overwatering Plants.
How To Fix
You should only water your cypress tree when it’s particularly dry during the summer or when a depth of about four inches (10.16cm) into the soil feels dry.
To prevent overwatering your tree, you should apply mulch to it. You can do this with materials such as bark chips, conifer needles, or compost. Ensure that you apply it to cover the ground underneath your tree to a depth of approximately three inches (7.62cm). This will preserve the soil’s moisture.
Mulch has other benefits for your cypress tree, such as infusing its soil with nutrients so it can grow. Research has found that placing a ring of mulch about three feet (0.9m) around the tree will double the tree’s growth (source).
4. Your Hinoki Cypress Tree Is Getting Too Much Wind
Although your cypress tree looks strong and as if it can handle various environmental conditions, you need to protect it from harsh, strong winds as these can cause damage to it (source).
It’s important to note that the hinoki cypress tree performs well in the U.S. Hardiness Zone 4, where plants can tolerate temperatures of 10 °F (-18° C), all the way to Zone 8a, which is marked by a minimum average temperature of 10-15°F (°C).
How To Fix
There are some effective ways to protect your trees from strong winds. These include the following:
- Preventing dryness and dehydration. If your cypress tree is not watered enough, it will be weaker and more of a target for wind damage because its branches and roots won’t be strong. Stick to a regular watering schedule for your tree.
- Prune your cypress in early summer. When the tree is experiencing growth, it will heal better from the pruning. However, prune it lightly just to shape the tree and remove dead branches.
- Cover your cypress. When your region is experiencing strong winds, cover your cypress with a protective cover. This will prevent damage from being inflicted by the harsh conditions.
It can be disappointing to see that the needles on your hinoki cypress tree are becoming brown. While this usually isn’t something to worry about, if your tree is displaying other symptoms, there could be problems with its care that need solving, such as:
- Your cypress tree is affected by a fungal disease.
- Your tree is being scorched by the sun.
- Your tree is getting too much water.
- Your tree is exposed to strong winds.