How to replant
Why do it?
In nature, plants can develop their roots unhindered. They are able to look for nourishment in all directions. Even if they grow in small cracks, mother Nature takes care for enough nutrients can be found.
In a pot, the roots are stuck. After a while, the roots will completely fill the pot and they may even outgrow it. Furthermore, the soil will become saturated with chalk (from the watering) or remainders from the fertilizer.
What kind of pots do we use?
In the old days people used red terra-cotta pots, but now we can use black or brown plastic pots. The black are better because they absorb the warmth more easily , which is certainly a advantage in our climate.
Never use too large pots. First of all it is aesthetically not justified - you don't want to look for the small plant in the large pot - but furthermore it is better for the plant that the pot is just big enough so that it can enjoy the warmth at its maximum.
How to repot?
To repot a very spiny plant without pricking one's fingers, is not that obviou. Even with gloves you may hurt yourself easily.
A simple tric to the to do it without hurting yourself, is rolling up a piece of newsprint paper around the base of the plant and grasp the two ends of the paper firmly with 1 hand and so detaching the pot with the other hand. Then place the plant in a new pot. Adjust the size and the thickness of the newspaper on the size of the plant. It does not work with plants of more than 25 cm diameter, but for all the others it is a clever aid.
When to repot?
In principle you can repot the whole year thru. Yes, in wintertime as well, but then surely on condition that the new soil is rather dry and that its temperature is at least 10 degrees Celsius. But basically the best period to do it is between March and September. Then you will have the least risk on losses and the reptted plants have some time to recover.
How often do you have to do it?
It is not necessary to replant your cactuses every year, at least not for those plants that are older than 3 years. Seedlings have a separate regime.
A plant that stands in a good pot and that has get regularly nourishment and water, can hold up to three years without being repot. In this way the roots will not be disturbed every year, but the potmedium will be as good as an be.
How to treat seedlings?
Seedlings should be planted out after a few months (when they are about 1/2 cm tall). You remove them carefully from the sowing pots and plant them nicely in rows on ca. 1/2 cm from together in a low tray.
When they are at least twice as big the year after, we reopt them best in a small pot, used for a picture film (prick with a hot needle a few holes in the bottom for the water drainage) and only the year after they are being repot in a 5,5 pot. Afterwards they can be treated as described above.