Thuja is one of the most popular hedge plants. It not only grows quickly, but also forms a dense privacy screen. Occasionally, especially when autumn arrives, the conifer starts to turn brown from the inside out. It is a recurring phenomenon that does not harm the plant. It only becomes a problem when the brown areas expand and the tips of the shoots change color.

discoloration in winter

The occidental tree of life , as the thuja is also called, originally comes from the region of Canada and the north of the USA. She is used to extreme temperatures and can adapt to them. This is exactly what the shrub does when it starts to turn brown from the inside in autumn. The plant is then in winter mode, where it can no longer take care of all parts as well.

In addition, due to the limited light supply, it can carry out less photosynthesis. Exactly those parts of the plant that are inside then lose their green color because they only get little sun anyway and therefore cannot photosynthesize efficiently enough with the remaining light that is available.

If the Thuja hedge turns brown inside in autumn or winter, this is initially a normal process that is not a problem for the plant. It only becomes a problem when the discoloration spreads to the shoot tips or the plant begins to shed the scaly leaves.

Note: Wild varieties such as Thuja occidentalis or Thuja plicata are particularly prone to discoloration. Modern cultivars such as Brabant or Columna are not as prone to discoloration.

Danger from salt

The thuja hedge is often located adjacent to a road. In this case, brown discolouration should be observed more closely from the inside. Like many other conifers, the Thuja is very sensitive to salt and reacts with brown leaves and shoots, among other things. These form primarily in the lower area, starting from the inside and then spread to the tips of the shoots. Especially in very snowy or icy winters, where a lot of salting is used, this causes problems for the Thuja hedge.

The following measures should be taken if the thuja has been damaged by salt:

  • Splash the conifers liberally with water to wash off the salt
  • Water the hedge well so that the salt moves to deeper layers
  • Cut off dead plant parts on frost-free days
  • if you make deep cuts in the wood, seal them
Tip: If there is the possibility of digging a small drainage ditch, the conifers can be relieved somewhat, since part of the salt water is diverted away.


Many gardeners like to mean it a little too well when it comes to fertilizing. In particular, mineral fertilizers such as blue grain behave in the soil like road salt. The mineral fertilizer increases the salt concentration in the thuja hedge, which can cause brown discoloration.

As an immediate countermeasure, the amount of fertilizer should be significantly reduced. Then you can water more, but without waterlogging. As a result, the mineral fertilizer is flushed into lower layers, similar to salt, and the concentration in the plants normalizes.

Gardeners cannot avoid a strong pruning in this case either. The tips have died and can no longer regenerate. In this case, space must be created so that other branches can cover the spots.


The thuja hedge is much better prepared for cold temperatures and suffers accordingly when it is very hot in summer or there is no rainfall. In this case, the conifer begins to turn yellow from the inside out and then turns brown right up to the tips.

A quick remedy is good, penetrating watering of the hedge. You should always water close to the ground. Dry summers are particularly problematic for older hedges. Here it can make sense if they are subjected to a vigorous pruning on a not so hot day. As a result, the plant has to supply fewer side shoots, which also saves you water.

Tip: To prevent the soil around the thuja from drying out too quickly, the soil around it can be covered. Bark mulch is ideal for this purpose, as it protects the soil from drying out.

root rot

There are different diseases that can cause the thuja to turn brown. However, these can be recognized quickly, as the discolouration primarily goes from the outside inwards. Only with root rot does the Thuja hedge also begin to turn brown from the inside.

Root rot is a fungal disease that gardeners can’t do much about. Root rot spreads very quickly and will kill the plant within a season, so you need to act quickly.
Countermeasures for root rot:

  • Reduce watering of the hedge
  • dig up affected plants
  • Dispose of the plant in the residual waste
  • Treat neighboring plants with a suitable fungicide as a precaution
  • Check neighboring plants regularly and react immediately if there is further infestation

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