Japanese yews are some of the most beautiful plants known to the Eastern World. These small shrubs provide the perfect amount of greenery as houseplants. Sometimes, however, they start turning yellow, which can cause concern.
Usually, if a Japanese yew starts turning yellow, it’s because either the soil has been collecting too much water or it contains mineral and nutrient deficiencies. The yellowing could also be due to a disease such as root rot.
Today, we’ll look at each of these reasons in a little more depth. We’ll also talk about some ways to fix the problem.
Check out the DynaTrap Mosquito & Flying Insect Trap – Kills Mosquitoes, Flies, Wasps, Gnats, & Other Flying Insects – Protects up to 1/2 Acre (link to Amazon).
1. The Soil Is Collecting Water
Japanese yews aren’t a big fan of standing water. The plants do best when they’re in soil that drains well. While some varieties prefer moist soil, the majority of them prefer dryer conditions.
Wet soil in these plants will often lead to diseases such as root rot. However, the first sign that the soil has been collecting water is almost always the leaves beginning to turn yellow.
One of the reasons that this happens is because the water depletes the soil of oxygen. This can cause serious root damage, manifested in leaf discoloration.
Most often, this problem manifests when the plant sits in standing water, because of overwatering, or if the plant is in soil that holds onto water. This is especially common if the plant is in a pot that isn’t self-draining. Sometimes it’s hard to tell how much water the plant contains before it begins to pool.
It can be enormously hard to drain the water once it’s begun to pool, so the best option is always prevention. Let’s talk about some ways that you can go about fixing this issue.
How To Fix It
The best way to fix soil that’s collecting water is to get it to a point where it drains better. This is assuming the issue isn’t with your pot. If the latter is the problem, you’ll want to replace the pot with one that is self-draining.
When the soil is the problem, you’ll want to add various ingredients, sometimes known as soil amendments. Usually, adding peat moss and perlite will help break up the soil to give it just enough draining qualities.
You can also add compost, farm manure, and shredded leaves, which can help tremendously with draining qualities (source).
2. The Plant Has Mineral or Nutrient Deficiencies
A plant can have many mineral and nutrient deficiencies, but one of the most common is nitrogen deficiency. When a plant lacks nitrogen, the first thing you’ll notice is nearly always a yellow discoloration on the leaves.
All plants, including Japanese yews, need three primary nutrients to flourish:
- Nitrogen: Nitrogen is part of the chlorophyll molecule, which gives plants their green color (source). With this in mind, it’s probably not a surprise that when plants experience a deficiency in nitrogen, the leaves begin to yellow. Nitrogen also contributes to the food creation process.
- Potassium: Potassium is essential for plant growth. It helps the plants to use water and resist drought. It also contributes to the plant producing a better crop of fruits or vegetables. You may notice yellowing in the leaf veins if the plant lacks this mineral.
- Phosphorus: Phosphorus is used for the photosynthesis process, storage and transfer of energy, and respiration in the plant. It is also linked to the DNA and RNA within the plant. Without this mineral, the plants can’t produce strong roots or good fruit and will typically experience discoloration.
A lack of any of these nutrients can cause yellow discoloration, but the most common cause of intense yellow discoloration is nitrogen. The second most common cause of discoloration is potassium. However, a problem with potassium usually centers around the leaf veins rather than the whole leaf.
How To Fix It
Before adding nitrogen-producing matter, always test your soil to verify that it has a nitrogen deficiency. Otherwise, you can cause harm to the plant.
To add nitrogen to the soil, try adding these organic materials to your soil:
- Composted Manure
- Green Manure
- Nitrogen Fixing Plants (Peas & Beans)
- Coffee Grounds
3. The Plant Has Acquired a Disease
Diseases are all too common in plants and unfortunately, the Japanese yew is not an exception as it can be affected by various diseases. However, most commonly, when the plant’s leaves turn yellow due to a disease, it comes down to the plant experiencing root rot.
Root rot is a common disease in plants and goes hand in hand with the issue of the soil having too much water. Therefore, standing water and wet soil are key contributors to root rot in plants. This is a problem because as mentioned earlier, the water sucks out all the oxygen the plant roots need.
If left untreated, root rot will multiply, and you’ll notice more than just the leaves appearing yellow. The branches will also take on a yellowish hew and begin to rot over time. Additionally, growth will be stunted, and the plant will eventually die.
Luckily, root rot can be treated.
How To Fix It
Root rot has to go away independently, but the first step is to drain the soil. Because an overabundance of water most commonly causes this disease, it’s always best practice to allow the plant to be stripped of water for a time.
You’ll want to leave it until the soil feels almost completely dry and then water a little at a time over a few days. You want to ensure that the soil is draining adequately. If you need assistance with this, check out the section above where we discussed the materials you can add to your soil to help it drain better.
You can also apply certain fungicides, such as fosetyl-al (link to Amazon), which can help prevent phytophthora infections – the infection that causes root rot.
Japanese yews typically experience yellow leaf discoloration when the soil drains poorly, when the plant has a mineral or nutrient deficiency, or when the plant has acquired a disease such as root rot.
One of the best things you can do for both root rot and soil holding on to water is to add other materials, such as peat. This will help the soil drain water thus reducing the amount of water the plant is sitting in.
You can also test your soil to see if it has any mineral or nutrient deficiencies and then act accordingly.