Our recommendations.
These are the requirements you should consider when growing Kiri trees – benefit from our 14 years of expertise
Our Kiri trees hybrids (Paulownia hybrids) can be successfully grown under a variety of different growing conditions. Nevertheless, many conditions must be thoroughly considered. In particular, climate, soil conditions, wind exposure, as well as the quantity and quality of the available water are key aspects for growing Kiri trees successfully.
The following recommendations for selecting the right growing site result from our own growing experience of more than 14 years, as well as from the experience we have gathered from our customers in more than 30 countries of different climatic regions. These recommendations are intended to serve as indicators for your personal site selection. However, they are no substitute for an individual site evaluation – we will be happy to support you in this.
These temperature ranges are suitable for growing Kiri trees
Our Kiri trees hybrids can be successfully grown in a wide temperature range. Nevertheless, the temperature range shown should be understood as a rough guide. In addition to absolute temperatures, many other factors are crucial in site selection. For example, water and nutrient supply and tree age can have a strong influence on the temperature tolerance of Kiri trees. In general, it should be noted that young trees can react particularly sensitively to temperatures that are too low or too high, especially in the first two to three years of cultivation.
Sudden sharp rises or sharp drops in temperature can also cause plant stress and damage compared to steady and slow temperature changes. Nevertheless, the following figure serves as a guide. In this regard, please refer to the information in our variety descriptions, as our four protected hybrid varieties also differ in terms of recommended temperature ranges. Also note that temperature tolerance increases as the Kiri trees age.
Required precipitation for the growing of Kiri trees
Compared to most other plantation woody plants, Kiri trees exhibit high water use efficiency and drought stress tolerance. Nevertheless, like any other plant, the Kiri tree is dependent on an adequate and consistent water supply until root development and rooting depth are sufficient. Already established tree stands are generally not dependent on irrigation, but water is the limiting growth factor in most cases. Tree growth can be increased as water supply increases.
Generally, a total of at least 600 to 800 mm of precipitation should fall during a six- to eight-month growing season. If no prolonged droughts occur during this period, supplemental irrigation of Kiri trees can generally be omitted. In regions with an unreliable or strongly fluctuating precipitation distribution, we recommend at least stationary initial supplementary irrigation in the first two to three years of cultivation.
What altitudes are suitable for growing Kiri trees?
Kiri trees are able to grow even at high altitudes. Natural Kiri tree stands occur in tropical climates up to an altitude of 1,700 m and develop well even under these conditions. However, no general statements can be made about altitude. The interaction of complex factors requires experience and individual advice. Please contact us if you are planning to cultivate Kiri trees at higher altitudes and we can assist you with our expert knowledge.
What wind exposure can Kiri trees withstand?
Kiri trees are generally sensitive to strong winds and storms due to their large leaves and rapid height growth. This is especially true for the first two to three years of cultivation. During this time, the trunk’s thickness growth is not yet pronounced enough to withstand strong winds.
In addition, Kiri trees in leafy condition during the growing season are more at risk of damage from strong winds and storms than those in non-leafy condition. In this context, please also note the information in our variety descriptions. Variety differences also exist here with regard to wind tolerance.
What is the vegetation period required for the cultivation of Kiri trees?
The vegetation period describes the time from the budding of the leaves to leaf litter. In general, the longer the annual growing season, the higher the annual growth and the shorter the time to wood maturity.
With respect to the growing season, we have been told that Kiri trees growing in the equatorial region without extended dry periods over a growing season of 12 months retain their leaves throughout the year. Thus, harvestable logs can be produced there in a much shorter period of time.
What soil conditions do Kiri trees need for healthy growth?
In addition to a high-quality and strong-growing variety, suitable soil conditions are one of the basic requirements for the successful growing of Kiri trees. At this point, we would like to urgently point out that Kiri trees grow very poorly or not at all on unsuitable soil sites. Conversely, suitable soils help to produce high volumes of wood with excellent quality characteristics within a very short period of time.
The ideal soil pH for successful growing of Kiri trees
Kiri trees can be successfully grown in a relatively wide range of pH. However, in some soil types, too high or too low pH values can severely limit nutrient availability, leading to nutrient deficiencies.
What nutrient content should soils have for growing Kiri trees?
Depending on soil type and previous use, soils have very different nutrient contents. We recommend determining the nutrient content by means of a soil analysis as part of the site evaluation. The results provide information about nutrient elements that are not sufficiently available in the soil. In addition to an analysis for the NPK content, the micronutrient contents should also be determined. The lack of essential micronutrients can lead to severe growth depression. Missing nutrients can be compensated by fertilization, we are happy to advise you.
What soil structure is required for the operation of Kiri trees plantations?
We have evaluated our results of many years of soil evaluation at various locations around the world and are happy to make this knowledge available to our customers: Kiri trees require deep, loose, well-ventilated soil for healthy root growth and rapid wood growth. We strongly advise against sites that tend to be waterlogged or have layers of clay or rock near the surface.
When selecting your site, it is also essential to analyze the soil samples taken for grain size composition in addition to nutrient levels and pH values.
If you are unsure how to collect the soil samples, we will be happy to send you our soil sampling instructions. You are welcome to send us the analysis results of your soil laboratory. We will evaluate them for you free of charge and without obligation.
We are aware that taking and analyzing samples involves work and costs. However, from our experience, the soil structure is an important aspect to ensure a successful cultivation project for you. Unlike annual crops, where you can change crops the following year if the soil is unsuitable, you want your trees to grow healthy and vigorous for many years on the carefully selected site. This is the only way you can achieve high yields.
Is an irrigation system necessary for a successful Kiri tree plantation?
Whether artificial irrigation is necessary growing Kiri trees in the selected location, refer to the explanations in the section on precipitation.
When planning an irrigation system, the available quantity of water and its quality must be taken into account as part of the site selection. However, the annual water requirement in addition to precipitation varies greatly depending on precipitation distribution, soil structure and groundwater level. Therefore, we cannot make any general statements about the required output of your irrigation system.
As a general rule, the following applies to water quality: the lower the salt content, the more suitable the water is for artificial irrigation. Again, we recommend having the water analyzed in a qualified laboratory. Please note that there can be considerable fluctuations in salt content throughout the year, especially in river water, but also in well water. We would be happy to evaluate your analysis results for you in a first step, free of charge and without obligation.
What are the legal aspects to be considered?
As part of your site selection, please inform yourself about the legal framework applicable at the site for the cultivation of kiri trees on short-rotation plantations. In many European countries, Kiri tree plantations are classified as agriculture and retain their agricultural status as so-called short rotation plantations or agricultural plantations with harvest cycles of less than 20 years. Depending on the country of cultivation, the legal framework may differ, which is why you should seek legal advice from local experts if in doubt.
You would like to learn more? Contact us!
We are happy to advise and accompany you. From site analysis, import, variety selection, planting and care, to harvesting and selling of your Kiri wood logs. Call us today or send us a message via our contact form. We look forward to hearing from you.