125 AA KOBER is a rootstock, similar to 5 BB Kober in terms of vigour. It is not suited to varieties prone to coulure. The Winegrowers Supply company in Somerset says 125 AA “adapts to a very wide range of soils. Particularly useful for heavy soils which are poorly drained, or for poor stony dry soils. Very good limestone tolerance; up to 50% total, 30% active. Resistant to chlorosis. Strength of growth is vigorous to very vigorous, a little less than 5BB; so a good choice for wide planting training systems. Suitable for all Vitis vinifera varieties but less good for those which are sensitive in flowering (Siegerrebe, Gewürztraminer etc).”