Hello to all! Potassium magnesium sulfate (Patentkali) is a basic fertilizer for leaf green and plant strength. It is said, that plants develop afterwards better cell structures and have a higher chance of surviving the winter. Depending on the climate zone, fertilization should take place in July/August if possible, and in September at the latest.
Rose propagators and professional rose breeders recommend here the product for hardening the wood before winter. Certainly, the usage depends more on the climate zone. Nevertheless, what do you think about this matter? Many thanks for your assessment.
I’ve never heard of it in the US, but I am curious what the recommended dosage is? My initial reaction is that it supplies a lot of magnesium that is usually abundant (or at least sufficient for roses) in most soils.
Two German Rose nurseries provide the following information:
Patentkali works regardless of the pH value of the soil and can therefore be used in all locations. Spread 70 to 100g of Patentkali per m² evenly and dig it in. Water well after application. For normal to heavy soils, Patentkali is applied once in late summer (August/September). For very light soils, spring or summer fertilization is even recommended. As a rule, application every two years is sufficient.
It is important to fertilize with Patentkali Kalimagnesia in August-September. This fertilization strengthens the cells, makes the plant more resistant, and gives your roses the necessary winter hardiness. Hardened rose plants can withstand a few degrees more frost than others and are also more resistant to fungus in the spring.
I myself have no experience, but am only passing on the information I found.