Most Catalpa are deciduous trees that typically grow 12 to 18 metres tall, with branches spreading to a diameter of 6 to 12 metres. Catalpa are fast growing trees. They have characteristic large, heart shaped leaves. Two North American species, C.bignoides (Indian bean tree) and C.speciosa have been widely planted outside their natural ranges as ornamental trees. These are the species found in the UK and Ireland.
Culture for Catalpa
Catalpa prefer a moist but well drained, fertile soil (pH 5.5 to 6.0) in a sunny position although they will tolerate a heavy clay soil. Shelter from strong winds as these may shred the large leaves. Protect from late spring frosts when young.
Concerns about Catalpa
In general a relatively pest and disease free tree. Outbreaks of verticillium wilt have been recorded these are rare but usually cause rapid wilting and death of the plant. Leaf blotch can be problematic but not life threatening. Likewise powdery mildew has, on occasion, been observed on Catalpa but is not considered a serious threat. Identified as a drought tolerant species so irrigation may only be required in a severe drought.
Management Practices for Catalpa
Sample soils for nutrient and pH levels. Fertilise or amend soil based on soil analysis. Check soil drainage potential and compaction levels. Root collar excavate where deep planting is suspected. Treat foliage preventatively with fungicide sprays if leaf blotch is observed. Send samples for lab analysis if verticillium wilt is suspected.