Bud formation and growth in Christmas trees
The number of trees of excellent quality is still increasing due to the improved growing methods. Bud formation, root system and correct growing methods are crucial for the quality of the harvested tree.
Top buds and whorl buds
In the growth phase, a top bud with many internode buds is your guarantee for a high quality tree, and if the tree has enough whorls with the correct distance at harvest time, then you will get an excellent Christmas tree.
The whorl buds ensure the outer density of the tree, while the internode buds ensure the inner density. The tree has to produce more and more buds each year in order to achieve a high rating. On the sketch you can see the average amount of buds each tree should be developing in order to become a salable tree.
In May/June you will be able to see how many buds next year's shoot will bring. The genetics in the tree are of course essential to the number of developed buds, but also the concentration of the plant hormone cytokinin in the shoot is essential.
Cytokinin is mainly formed in the root tips and carried in the wood, which are the aquatic parts of the plant, and further up the plant. An effect of the hormone has been observed even at very low concentrations in the plant issue. Of course, the amount of active root tips at the time of bud development is closely related to the result. Other circumstances, such as development and vitality, of course also affect the formation of buds.
How to optimize the growth of the root system on Christmas trees
Roots need air, water and nutrition to grow.
Basically, a good soil structure with many pores is important so that the air can get all the way down to the roots.
In order to help the Christmas trees grow well, it is crucial that you, before planting your trees, cultivate the soil correctly. In this way, you will be able to improve the structure of the soil and thereby ensure that the trees can spread their roots.
The humidity in the ground during the bud formation has proven to have an effect on the number of formed buds.
If you plant your trees a year where the spring is dry you must expect a negative effect on the formation of buds. You may expect the same the first year after planting of the tree. We recommend that you plant your Christmas trees in the fall where the soil usually is more moisty. When planting in the early fall the plants have time to form new roots and get well established at their new growing site during the moist fall and winter time, before the often dry spring season sets in. In this way the trees are more robust and get started faster, when the spring and the new growth season begin.
Planting, growing methods and Christmas tree plants
When planting Christmas trees it is important to ensure that the sides of the planting hole are not pressed too hard together. If this happens, the roots will not be able to spread in the ground and the tree will get the so-called "flat" roots. The optimal way of planting is therefore three-dimensional allowing the tree to develop its roots.
In the drawing below you can see the two most commonly used planting techniques, hole planting and drill planting.
Which growing method ensures the quality of the Christmas trees?
In addition to the planting techniques and growth conditions mentioned, the fertilization and weed control have a great impact on the root growth and also on the production of cytokinin, which is very essential for the formation of buds.
The negative effect from weed has been proved in a multiannual experiment, where the growth of trees on an area with cut grass was compared to the growth of trees on an area with naked soil. The trees on the area with grass were smaller and with more superficial roots than the trees planted on the area with naked soil. Therefore, we recommend that you keep your Christmas tree culture as weed-free as possible.
Fertilization of the trees has to be adapted to the soil conditions as well as the trees on the area. We always recommend that you make a soil analysis as well as a needle analysis before you decide how to fertilize your trees.
Which Christmas tree plants to choose?
In addition to the soil conditions, the quality of the plants to be planted is of course very important. Especially the root system is important. Make sure that your Christmas tree plants have a large number of fine and vital roots. In this way you ensure that the trees after planting will grow fast and get well established.
A poor root system means that the plant stops growing completely the first years. Only the lower whorls will develop and will dominate the top leader, which will be starved and "cheated" for the small amount of cytokinin that the root tips develop.
The result will be that the number of buds in the upper part of the tree decreases.
Below you can see three different examples on how the roots on at tree can develop.