Tui are a popular choice of ornamental plant, frequently planted in gardens, public spaces, parks and squares. These conifers are a popular choice for use as hedges, as they can be easily shaped into different forms. It is worth noting that even yews are not immune to certain weaknesses. They are prone to browning and gradual desiccation. What is the recommended course of action?
Characteristics and varieties of thuja
Thujas (also known as lifesifters) are coniferous plants that are native to South America and Asia, with a particularly strong presence in Korea, China and Japan. In these locations, they play a significant role in forest ecosystems. The height of these trees can range from 10 to 20 metres, with trunks reaching up to several metres in diameter, depending on the species. However, this growth can be regulated by regular pruning, allowing the tui to be kept to the desired size.
The most commonly cultivated species are the western thuja (Thuja occidentalis) and the giant thuja (Thuja plicata). The former can reach heights of between one and fifteen metres and displays a seasonal change in foliage colour in winter, from the usual green to brown or yellow. By contrast, the giant thuja is the largest of the thujas, with a height of up to 60 metres and a trunk diameter of 2.4 metres. This species requires specific conditions, including moist, fertile soil and an abundance of sunlight.
Why do yews turn brown and dry out?
While thuja is a popular choice, these plants require more care than they might initially seem to require. The most common issue encountered by growers is the browning and desiccation of thuja plants, which can have a number of underlying causes.
Lack of water in winter
It is important to note that tui require water throughout the year, both in summer and winter. If they are exposed to frost for extended periods during the winter months, they are unable to draw water from the frozen soil, which can result in what is known as physiological drought. The consequences of this lack of moisture are frequently not evident until the following spring or summer.
Diseases and fungi
One of the most common causes of death of Thuja is attack by fungal diseases such as Phytophthora. This disease causes stunted growth, discolouration and, in the worst cases, death of the plant. The initial symptoms may be observed as early as the beginning of summer. The recommended course of action is the use of fungicide products and timely watering with a dilute solution. In the event that the infection has reached an advanced stage, it will be necessary to remove and burn the infected plant in order to prevent the disease from spreading further.
Instructions for correct fertilisation
It is important to fertilize the thuja regularly for better health. There are two ways of fertilizing:
- Soil fertilization: The basic method in which important nutrients are supplied directly to the soil.
- Foliar fertilization: A less common, but in some cases more effective, method in which nutrients are delivered directly to the leaves and needles of the plant.
The most beneficial fertilisers for a yew tree are compost and browned manure, which provide essential nutrients to the plant. For foliar fertilisation, magnesium sulphate is an excellent choice, as it improves the plants’ ability to take up nitrogen and phosphorus.
When and how to prune yews?
To ensure the continued attractive shape and healthy appearance of your yews, regular pruning is essential. The optimal timeframe for this is between March and August, with a minimum of three pruning sessions per year. It is recommended that the first pruning take place at the turn of March/April, the second in June when new growth starts to darken, and the last in early August.
