It is not hard to find many myths regarding the growing of Cercis and in spite of Treetyme giving out information the same ones seem to repeat regularly. So here are 3 points of clarification:
Firstly in the UK Cercis are best not to be used as shade trees. This is ok when grown in their native climate where light levels are high and intense, but in our climate it is not necessary and in fact is detrimental to both the flowering and leaf colours. Semi-shade can be acceptable in the south, but from the midlands north we recommend a good bright place in the garden or patio.
Secondly Cercis perform well on a wide range of soils and PH. In their native habits the PH is usually high(8-9.0) and not acid as is often written. However the canadensis and chinensis will grow very well on soils from PH 5.5-9.0.
Thirdly it is sometimes advised not to feed Cercis. This is mistaken advice based on an assumption that because they are members of the ‘Legume’ family they produce root nodules and applications of fertilizer will damage these. Cercis do not fix nitrogen in their roots and do benefit from regular fertilising in the early years after planting and even later occasional high potash feeds in early summer can improve the flowering potential for the following spring.
From the Treetyme team.