To feed Cercis, or not?

There are some in the plant world who suggest that Cercis should never receive fertiliser. This is based on the assumption that because 
they are members of the ‘Legume’ family  this would damage the root nodules and prevent development of this small tree. However Cercis do not have have the 
ability to fix nitrogen as many legumes do. 
So why fertilise Cercis? Firstly young growing smaller trees and shrubs benefit from having the optimal 
nutrients they need for growth and in the early stages (first 5 years) before their root system is developed, it is very unlikely that the 
soil immediately around any plant will have all that is required. But with Cercis there is another reason to give a high potash feed in late 
July and that is to ripen the wood. This is not so necessary in the hot regions where many Cercis are grown such as the Mediterranean or the USA, 
but here in the UK, even in the south, the average temperature is fairly moderate and an additional application is usually beneficial. The 
results are better, flowering in the spring following and also less die-back of the new growth during the winter, especially if it is a long winter 
with a cool spring. While die-back is unlikely to be severe enough to kill a small tree it can cause unsightly damage and require remedial action as
new growth starts from a lower bud. The cooler the summer or the further north the trees are grown, then, in our view, the more necessary it
is to give this feed in the summer period. As the plants mature then the advantage becomes less as the tree should have developed the root 
capacity to derive all its required nutrients from the soil, however on poor marginal land maybe it can always assist.