Hans, I seem to have missed this discussion. But we tried using Kaliumsulfat instead of the
British potash in the same way as Ian does and bulbous plants in pot flowered much better.
Now I only grow plants in the garden.
I don't use organic fertilizer either, but for rock plants I always use fertilizer with low
nitrogen, for instance here we can buy NPK 7.14.28, which gives for these plants the best
results. What Ian uses is about similar, Low Nitrogen and high Kalium
Here I quote Ian in his Bulblog:
Every plant food should display the analysis as a formula N. P. K. and above you should be able to see 5.3, 7.5, 10 so this mix has 5.3% N, 7.5% P & 10%K plus it has added magnesium (helps the plant produce chlorophyll) and trace elements. It is this analysis that should guide you to which plant food you will use.
I don't see why not using the Kaliumsulfat because there is more Mg. in it as seemingly in
the Potash Ian uses.
When we grew plants commercially I remember we always gave our beds before planting our
stock plants for propagating, Superfosfat and Kiseritt(Magnesium).
We produced about 20 years ago for instance more than 100.000 Aubrieta in 9 cm pots yearly.
And in one year we forgot to give the Superfosfat on one stock bed. The propagated plants in pots
from this bed flowered in the next year much less and we could not sell them as flowering plants in the quality our customers were used to receive from us.
BTW. Luc is from Belgium, but we speak the same language.
