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Thuja are one of the most popular plants in English gardens, valued for the privacy they provide and their lush green color. However, the sight of browning needles can worry any gardener. Is it a natural process of preparing for winter, or perhaps an alarm signal indicating a fungal disease or care errors? In this article, we will analyze the 7 most common causes of thuja browning and give you tips on how to effectively restore their healthy appearance.
Why does thuja turn brown? Natural processes vs. cultivation errors
Did you notice brown needles inside your hedge and your first thought was to say goodbye to the plant? Relax, put down the shovel! We have the feeling that this is one of the most common reasons for unnecessary panic among gardeners. In most cases, what we mistake for a disease is simply physiology. Seriously, plants can be pragmatic – if sunlight doesn’t reach the center of a dense shrub, the thuja considers these shoots as extra weight and stops investing energy in them. It’s a bit like tidying up a closet: we get rid of what we don’t use anyway.
Before you start suspecting the worst, it’s worth taking a look at exactly where the changes appear. Is it the tips of the shoots, or maybe just their interior? Understanding this difference is half the battle in care. According to experts from the Twój Domowy service, browning from the inside of the thuja is completely natural, especially in older and very dense specimens that are defending themselves against a lack of light and airflow.
To make your diagnosis easier, we’ve prepared a quick cheat sheet to help distinguish nature from health problems:
- Natural internal browning: Occurs deep in the crown, shoots are dry but crumble easily. This is a result of shading.
- Autumn color change: The entire plant may take on a copper or brown tint (especially the popular ‘Brabant’ variety). This is its protective shield against frost.
- Pathological tip browning: If young growths on the outside are failing, it could be a sign of water shortage, over-fertilization, or pest attacks.
- Black spots: That’s a different story – usually meaning a visit from a four-legged friend (dog or cat urine) or a fungal infection.
Autumn thuja browning – is it a reason for shame?
Absolutely not! This process is as natural as leaves falling from an oak or birch tree. Although thujas are evergreen, they also need to regenerate. In autumn, the plant withdraws sap from the oldest needles to survive difficult conditions. No one would want to waste energy maintaining shoots that don’t participate in photosynthesis anyway, right? Such a survival strategy allows conifers to focus on what’s most important – protecting roots and healthy tissue from frost.
Remember that a dense hedge is a small ecosystem. Sometimes it’s enough to gently “comb through” the dry shoots from the center with your hand (in gloves, of course!) to make room for fresh air. Don’t worry that the gaps will stay with you forever – in spring, nature will quickly fill these holes. By the way, before you decide your trees need strong chemicals, check if they are simply too crowded. Often, it is planting them too densely that makes the center of the thuja turn brown faster than we would like.
7 most common causes of thuja browning
The sight of a failing hedge can ruin the mood of even the most patient gardener. However, before you reach for the shovel, we have good news: most problems with arborvitae can be solved, provided we make an accurate diagnosis quickly. There are several causes of browning, and each sends us slightly different alarm signals. The key to success is a careful look at the needles and branches, because the plant tells you what hurts it.
Let’s remember that thujas are quite gluttonous and thirsty creatures. We often think that since they are “evergreen,” they will manage in any conditions, but that’s a big oversimplification. Our observations show that most problems result from an improper start or minor neglect in watering, which accumulate over time and hit the shrubs’ condition. By the way, did you know that as many as 85% of cases of problems with conifers result from cultivation errors, not from the fault of the seedlings themselves?
Understanding symptoms: Why is my thuja changing color?
The first culprit we most often encounter is physiological drought. It manifests as browning of the shoot tips, which looks as if the sun simply scorched them. This usually happens in spring when the ground is still frozen and the sun is already strong – the plant wants to drink but cannot draw water from the ice. Similar symptoms are caused by over-fertilization, which is the result of our over-eagerness. If we applied too many granules, the high salt concentration in the soil “pulls” water out of the roots, resulting in the characteristic drying of the needle edges.
The situation looks completely different when Phytophthora attacks – a dangerous fungal disease. In this case, we are dealing with yellowing of entire branches, and the process progresses from the bottom up. If you notice that the shoots become dull and the bark at the base of the trunk begins to rot and brown, it’s a sign that the root system is in trouble. As reported by experts from the biro.com.pl service, plants weakened by root diseases lose tissue consistency and stop conducting sap, which leads to the rapid death of entire parts of the shrub.
We cannot forget about our four-legged friends. If browning occurs only at the bottom, up to a height of about 50-60 cm, and creates distinct black spots, animal urine (dogs or cats) is to blame. The ammonia in urine acts like corrosive acid. On the other hand, pests, such as the cypress aphid, cause needles to become sticky and covered with a black coating. If your thujas are browning only from the inside, near the trunk, be reassured – this is often a natural lack of light. The plant simply gets rid of needles that do not participate in photosynthesis, which is a completely normal aging process. Finally, it’s worth mentioning severe frost; frosty, dry winter winds can dry out young growths, which manifests as a rusty color just after the thaw.
| Symptom | Probable cause | What to do? |
|---|---|---|
| Brown tips | Drought or excess fertilizer | Water abundantly, limit chemicals |
| Yellowing of the entire plant | Phytophthora (root disease) | Apply a fungicide |
| Black spots at the bottom | Animal urine | Apply low protective fences |
How to save browning thujas? Proven methods and sprays
Have you noticed that your thujas are losing their succulent color? Don’t panic! Browning of conifers is a common problem, but it can usually be solved if we act efficiently. The first step in our rescue plan is a thorough cleaning of the shrub. We must manually remove all dry, dead branches from the center of the plant. This will improve air circulation, which is an absolute basic to stop fungi from spreading. Also remember that thujas love to drink! They often turn brown from thirst, so systematic watering is a must, even in autumn before the ground freezes.
When the mechanical cleanup is behind us, it’s time for support “from the inside.” If the plant is clearly weakened, it’s worth reaching for specialized intervention fertilizers with a high magnesium content. They will quickly replenish deficiencies that manifest precisely as a change in needle color. However, if you suspect an infection, fungicides may be necessary. Just remember the golden rule: never spray in full sun! The rays could severely burn wet shoots. It’s best to do it in the morning or evening when the temperature is slightly lower.
Home remedies for healthy conifers
If you love natural solutions as much as we do, then garlic will become your best friend in the garden. The allicin it contains is a true “killer” for bacteria and fungi. According to the ESKA.pl service, such a home extract instantly deals with pests such as spider mites or aphids, which often secretly destroy our trees. This is probably the cheapest and most ecological method we know.
Preparing the mixture is trivially simple. Just crush about 4 cloves of garlic, pour a liter of warm water over them, and set aside for 24 hours in a cool place. After straining, pour the solution into an atomizer and spray the thujas, focusing especially on the lower parts where pathogens like to attack most. Repeat such treatment every 7-10 days. Seriously, the difference in plant condition is visible to the naked eye!
Prevention: What to do so thujas don’t turn brown in the future?
Instead of fighting the consequences, it’s better to simply prevent them. This is the golden rule for every greenery lover! We feel that most problems with thujas result from minor mistakes made right at the start. To keep your hedge lush green, we must take care of the foundations: space and regularity. Seriously, the plants will reward us tenfold if we give them some breathing room and stable living conditions.
The key to success is avoiding excessive densification. Although we want to quickly screen ourselves from neighbors, planting trees “one on top of the other” is asking for trouble. When plants are crowded, there is a lack of air circulation inside the hedge. This creates perfect conditions for fungi, which love such stagnant moisture. According to experts, the proper distance between thujas in a hedge should be between 50 and 80 cm, depending on the chosen variety, which allows for a healthy balance and light access for each branch.
Your care checklist – healthy thuja step by step
Hardly anyone likes complicated instructions, so we’ve prepared a simple cheat sheet. If you stick to it, brown needles will be a thing of the past:
- Watering during drought: Not only in summer! Thujas are evergreen plants that transpire water all year round. If autumn is dry and the ground freezes before the plants “drink,” physiological drought can occur in winter.
- Moderate fertilization: Don’t overdo it with nitrogen at the end of the season. Feeding plants too late stimulates them to grow instead of preparing for sleep, which makes young shoots freeze.
- Winter watering: Just a few warmer days in February are enough to make it worth pulling out the garden hose. Watering plants during a thaw is often the best rescue from spring browning.
- Sanitary cutting: Once a year, remove dead, dry branches from the center of the shrub. This will additionally improve the ventilation we mentioned.
Remember that thujas are quite gluttonous creatures, but they don’t like extremes. Too much water (standing mud) is just as harmful as its complete absence. However, just a bit of mindfulness and observing the color of the branches from time to time is enough to enjoy a beautiful wall of green for many years. Is it hard? In our opinion, absolutely not, it’s the pure pleasure of contact with nature!
Frequently Asked Questions (FAQ)
Do brown thuja branches need to be cut off?
Yes, regularly remove all dead, dry, and diseased shoots. Such a sanitary cut significantly improves air circulation inside the shrub and facilitates light access to young growth. Additionally, the immediate cutting of diseased parts limits the spread of fungal infections. Remember: always use clean and sharp tools to avoid infecting wounds after cutting.
Why does thuja turn brown from the inside?
In most cases, browning of thuja from the inside is a natural physiological process. It results from the plant’s dense habit, which limits the supply of sunlight to the interior of the crown. If, after touching, the branches do not crumble in your hands and no disease coatings are visible on them, you have no reason for concern. Check the condition of the shoots by gently parting the branches – if they are flexible, the plant is simply getting rid of unnecessary, shaded fragments.
What fertilizer to use for thuja browning?
Choose specialized fertilizers against needle browning, which are characterized by a high content of magnesium – a key element for the photosynthesis process and intense green. Before you apply the preparation, however, conduct a quick diagnosis and exclude other causes:
- Check the substrate moisture to eliminate physiological drought.
- Make sure the plant was not previously over-fertilized (too much salt in the soil also causes browning).
- Apply fertilizer according to the dose recommended by the manufacturer, preferably in early spring or summer.
