Thoughts on fertilizing Christmas trees

By: Allan Holm Nielsen, Flex Fertilizer System ApS

It is now about 3 years since we here at Flex Fertilizer System got a tip from a Norwegian Christmas tree grower that our fertilizers were quite good for Christmas tree production, and he asked us to spread the good news and his experiences. At the time, they set out to place an NPK starter fertilizer in the spring and give a Foliar N + Ca + Mg fertilizer 3 times during the summer to get a good quality of trees – something he then gave nice green trees, more side branches, less stretch growth. and generally better quality.

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We therefore began to familiarize ourselves with the situation of the Christmas tree producers here in Denmark, and have tested a number of fertilizers for effect and patience on the trees. And in general, there are no problems with using our products in Christmas trees. They work well and are safe to use. We also experienced that some of the products that were on e.g. the micro-market was very expensive – so expensive that in practice they were hardly used. And that there were 3 quality problems in particular among the growers:

  • bare shoulders due to Mg deficiency
  • red needles due to Ca deficiency in the young needles
  • algae growth

After talking partly with consultants and partly with researchers at the University of Copenhagen (“Landbohøjskolen”), we have also learned that Mg and Ca do not seem to be transported from root to new needle the first year – the problems you see arise from too bad admission the year before, and if one has to correct them at short notice it is not possible via the root. You have to enter via the “blade” = the needle.

We have therefore tested a number of our N18 / N22 foliar fertilizers and found that they give a quick effect on color (was demonstrated last year at Langesø Christmas tree exhibition), and compared with the Norwegian experiences with this type of fertilizer, where there are subsequently no problems with bare shoulders and red needles, could be an indication that these fertilizers have a good effect on nutrient supply to the needles.

Overall, we therefore bring this overview with fertilizers we have tested and believe there is good reason to consider if you want to increase the quality of your trees, while taking care of the environment through less leaching and less over-fertilization – and the wallet by the products is reasonably priced.


For spring fertilization, applied in early spring:

Base NPK 15-2-6 m microer (recipe 28.3) – for dribbling between the rows in the spring / during the year if necessary. 100-500 kg per hectare.

Base NP 10-7 with micro (prescription 305.2) – for placement at planting or dribbling at high P demand. 50-300 kg per hectare. Do not come into contact with the roots when placing.

Base N9 m Ca + B (recipe 212.1) – for dribbling between the rows in case of Ca deficiency and prevention of red needles. 50-200 kg per hectare.

Can advantageously be supplemented with e.g. Patent potassium for additional K and Mg supply. As well as liming for Ca assignment.

For foliar fertilization, applied in summer (June-July-August):

Foliar N18 m Ca + Mg + B (prescription 446.3, approx. equal amounts of Mg + Ca or recelt 255.7, predominance of Ca) – for the prevention of Mg and especially Ca deficiency. Spray on the needles in summer, about 50 kg / hectare per time. 8-14 days between treatments.

Foliar N22 + Mg or Foliar NK18 + Mg (recipes 120 and 121) for the prevention of Mg deficiency and as mixing partners for Christmas tree micro. Spray on the needles in summer, about 50 kg / hectare per time. 8-14 between. With at least 1: 1 mixture with micro, optimal uptake is achieved, as it lowers the mixture’s POD value so that it does not dry out.

Flex Christmas tree micro with all essential micros in Christmas tree-optimized ratio (recipe 470) – miscible with 120 and 121 for simultaneous application and better effect. About 5-10 kg per walk. Based on sulphate-containing microbes for more gentle action. Remember 0.1% adhesive dispersant (eg Agropol).


Areas of action for the fertilizers:

The basic fertilizers covers the basic amount of nutrients. Saving a little N for later reduces the risk of leaching. The complex-bound phosphorus is more available than normal granulated phosphorus, especially by location. Microer ensures that there is a bit of everything for the plant to start on.

This gives the trees a good start to the year and reduces the risk of growth stalling early in the season. When planting, you can provide the tree with enough nutrients for the first 2 years by placing a concentrated amount of about 5-10 cm from the root.

Foliar / leaf fertilizers covers the heavy nutrients and ensures that you can treat at short notice if necessary. acute nutrient issues. This is especially true of Mg and Ca, so you avoid the two mentioned quality problems, just shoulders and red needles. It is still important to be at the forefront. In addition, it seems that the algae problems that sometimes occur in the cultures may be due to the trees being stressed due to nutrient deficiencies, and that it produces “leaky” needles so that nutrients seep out on the surface of the needle. By ensuring well-nourished trees without defects, these problems should go away.

The fertilizers are color-coded here on the sheet, so brown can be mixed with brown, blue with blue and green with green – if you get the needs / ideas. NEVER mix Ca- and sulphate-containing fertilizers. It precipitates immediately. And mixtures with Fe + P in the same mix must be used within a few hours, as it is not long-lasting.

By e.g. acute phosphorus or potassium deficiency, we also have solutions for it, just as we are happy to help with a total plan where we include soil analyzes and equipment in the planning. Just tell me.

Overview and examples from attached Excel sheets:


For more information, please contact us at e.g. info@flex-fertilizer.com

Get order form

Here you can pick up an order form for ordering fertilizer. Fill it out and send it to info@toppii.dk