Personally, I grow another kind of Robinia that can withstand our cold winter. So I'll tell you how I do it with my plants.
The easiest way is seeds. Robinia grows rapidly and I saw flowers 3 years after sowing.
Reproduction by root offspring is simpler, but less productive. It's enough just to dig a piece of rhizome with a young plant and put it in a new place.
There is also a more effective way - reproduction by root cuttings. In the beginning or in the middle of May, several side roots of an adult plant are carefully dug out. Diameter not less than 5 mm, and length - not less than 20-25 cm. Small side roots from segments of larger roots are not removed. Such pieces of roots are slanted into a loose nutrient substrate. The upper section of the root is sprinkled with crushed charcoal and placed at the level of the soil surface.
With warm and humid weather, shoots appear in 2-3 weeks - by the middle of June.
Green cuttings of Robinia take root badly, and when using greenhouses without heating - only in hot summer. Apparently, in the climate of Moscow this method of reproduction is inapplicable.
Has the tree flowered at all please?
