Thuja hedges or a tree of life planted as a solitary can be found in many local gardens. But what if the tree gets brown needles? Many hobby gardeners then quickly resort to Epsom salt fertilizer because they assume there is a lack of nutrients. But the cause can also be quite natural and occurs regularly in autumn / winter. The following article explains when Epsom salt is necessary and when it is better to avoid fertilization.

Brown needles on thuja – causes

The causes of brown needles on the tree of life can be very different. Therefore, you have to react differently. Brown needles can occur in the following situations:

  • natural cause in autumn / winter
  • as with deciduous trees, the tree reacts
  • in spring it turns green again by itself
  • Overfertilization
  • Damage from road salt
  • Root rot due to fungal attack
  • dryness
  • Soil too acidic
  • Fungal diseases
  • Insect infestation

If a single cause has been identified, action can be taken with fungicides, insecticides, more frequent watering or less fertilizer in order to repair the damage.


If the thuja or even the entire hedge suffers from a magnesium deficiency, yellow needles are formed here, which only later turn brown. This deficiency can also occur with regular fertilization. If the shrubs in your own garden therefore show the following symptoms, then it could be a magnesium deficiency:

  • yellow needles
  • spread from the inside out
  • only turn brown later
  • fall off
  • Tree of life shows bald spots

You should act as soon as you see the first yellow needles so that the hedge becomes beautiful again and no holes can appear. To be absolutely sure that there is a lack of magnesium, you can take soil samples and give them to a laboratory nearby. Addresses for this can be obtained from horticultural companies or tree nurseries at your place of residence.

Note: Magnesium deficiency can occur at any time. This is because the mineral is water-soluble and is simply washed away with rain or irrigation water.

Use Epsom salt fertilizer

If a magnesium deficiency was clearly established in the soil samples, Epsom salt fertilizer can be used. Because only against this is the use useful and can save the thuja. For fertilization, attention should be paid to the right time, which should look like this:

  • in April with the new shoot
  • a second fertilization in summer
  • select the time before the second budding here
  • then add Epsom salt fertilizer regularly
  • always mix with compost fertilizer in spring
  • choose an overcast day
  • not in heavy rain
  • little rain, however, desired
  • frost-free
  • when there is frost, fertilizer is not absorbed by the soil
Note: A light rain on the day of fertilization makes the work easier. Heavy rainfall, on the other hand, carries the risk that the Epsom salt fertilizer will be washed out of the soil again immediately after it has been applied.

Fertilize properly

Epsom salt can be used in fertilization in different ways. However, you should always pay attention to the manufacturer’s instructions when using your own thuja, otherwise the desired effect will not occur. Because if you fertilize too much, this can result in over-fertilization, and giving too little Epsom salt fertilizer may not be able to compensate for the magnesium deficiency. Therefore, when using Epsom salts, you should pay attention to the following:

  • Pour solid Epsom salt directly onto the floor
  • water the soil well beforehand
  • Sprinkle fertilizer around the thuja
  • not directly on the trunk
  • not even directly to the roots
  • water again after the fertilizer application
  • so the Epsom salt can get into the ground with the water
  • Dissolve Epsom salt in water
  • spray on the underside of the leaves
  • leave out the trunk
Tip: The heavier the soil at the location, the higher the concentration of Epsom salts must be selected so that a positive effect can occur.

Not used with brown needles

If an individual thuja or the entire hedge shows brown needles without them having been yellow beforehand, then the cause is different and it is not a magnesium deficiency. However, if pure Epsom salt is given in such a case, this can reverse the effect and the tree is additionally over-fertilized when used, which can result in further brown needles. The fertilization of a thuja should therefore ideally always look like this, so that there are neither yellow nor brown needles:

  • fertilize in spring
  • use compost, horn shavings and dung for this
  • no risk of oversupply
  • Nutrients are gradually released

Bittersalz Definition

Epsom salt is also known as magnesium sulfate, which is the chemical name. Epsom salt is already contained in many fertilizers as an additive, but it can also be used as a single fertilizer in a variety of ways, for example in fruit growing and coniferous trees. For this reason, many hobby gardeners also use the fertilizer for their thujas, but this does not always make sense. Magnesium sulfate is said to promote an acidic soil that many plants want. In medicine, pure Epsom salt is often used as a laxative. It has the following composition:

  • sulfuric acid
  • Magnesium
  • occurring in nature as kieserite
  • colorless
  • odorless
  • bitter taste

Even if the belief is still widespread, in most cases Epsom salt fertilizer does not help against a browned thuja. First you have to find the cause, then you can take remedial action. It is only advisable to use Epsom salt if there is a magnesium deficiency, in all other cases it can quickly lead to over-fertilization and the tree of life is weakened even more.

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