Those who have repotted and followed recommendations for a well drained substrate should definitely remember to water their trees regularly.
There is hardly any waterlogging in the pond plant baskets, so watering over is hardly possible. In the current weather (sunshine every day) I water almost every 2nd day. The weight gives you an indication of whether watering is necessary.
The process of fine root formation may be delayed a little by regular watering, on the other hand the sun is already strong enough at the moment to dry out the pond plant baskets (depending on the location). About 4 weeks after repotting, fertilizing can be started with a very light concentration (1/4 of the specified dose). 3 weeks ago I potted the larches, the tufts of needles are getting bigger and I guess that I will fertilize with wuxal for the first time at Easter.
For those who want to use a product like Algan, the green light can already be given. Foliar fertilization can be carried out every week in a dosage according to the specifications. The trunk should also be sprayed.
How exactly do you use this liquid fertilizer now?
First the substrate is watered normally, then it is fertilized. I suspect that there are around 100-150ml of fertilizer per 20 pot. If fertilizing seems too risky for you, you can do a larger dilution of leaf / needle fertilization.
I can't say much about solid fertilizer, I will use a simple fertilizer on a few test plants this year and then next year we can switch to this inexpensive fertilizer if necessary.
I have been using a simple liquid fertilizer myself since last year, and because it is supplied as a coarse-grained powder in a plastic bottle, on the one hand the fertilizer is kept dry outside in any wind and weather, and on the other hand the fertilizer is easily stored in water can be dissolved or alternatively - so I think it - can be sprinkled on the earth in order to then water well.
So far, the fertilizer has worked well.
Of the components I am not so the expert, therefore listed here times, maybe someone knows whether it is really suitable:
NPK 13 + 7 + 13 ( + 3 magnesium) with boron, iron and manganese.
For me, the nitrogen value would be too high. As Dieter wrote elsewhere, a high nitrogen value strongly stimulates growth, which can result in weak and susceptible plant tissue as an adverse side effect. I would be careful with this stuff.
I can hardly say anything about the other values. I can only assume that phosphate stimulates root growth. The assumption is based on the fact that a "root turbo" discovered at Raiffeisen turned out to be an "NPK fertilizer" with the values 0-20-0 and a few extras. Also, Urikawa once wrote on the subject of yews that he fertilizes them with fertilizer with a high phosphate content, even through the needles, to stimulate root growth.
2. Another answer:
I can't say much about the fertilizer you cite. I tend to prefer balanced NPK ratios.
Let's make it complicated. In a bark humus substrate the fertilizer would work well, the further "decomposition" of the bark humus takes up quite a bit of nitrogen.
In a normal substrate, quite fattening growth would occur. The form (bond) in which the nitrogen is present is another issue. How much nitrogen is really available to plants.
I can't give a reasonable answer, I fertilize and see how the plant reacts.
I help myself with the thought that the plants already take the part they need. The rest I simply flush out.
Because of this uncertainty I prefer balanced fertilizers.
Potassium serves to harden the cells and increases frost hardiness (according to literature).
How long should I wait after repotting with root pruning before I can or need to fertilize for the first time?
Normally 4 weeks should be sufficient. The tree should already be clearly growing (i.e. not just budding).
A certain basic fertilization is already in the substrate. If you then start with very low dosage (I start with 1/4 of the given amount), you can see by the reaction of the plant if the fertilization was correct, too low or too high.
A sure sign of overfertilization is the blackening of the shoots, combined with withering, even though the substrate is moist. We will approach the correct measure in slow/small steps. This measure is different for everyone.
The only advice I can give: Get to know your plants, learn to distinguish the different greens, check on your plants every day.
Overfertilization can be deadly. Dying out can be deadly. Waterlogging can't really happen in pond planters.
And if you also give your plants some time off, at most some time of development will be lost, but the little tree will still be there.