The spherical trumpet tree is created by grafting a trumpet tree (Catalpa bignonioides) and is particularly striking due to its spherical shape. This grows completely naturally, so the tree doesn't actually need to be pruned. In addition, the ball trumpet tree – the “Nana” variety is particularly popular – remains significantly smaller than its up to 18 meter high relative. This means it is also suitable for smaller gardens and does not need to be kept in shape by pruning.
When and how should I prune a globe trumpet tree?
A ball trumpet tree generally does not require regular pruning; only thinning out the crown and removing dead or diseased trees is recommended. Young trees benefit from pollard pruning. The best time for pruning is between February and April, but not in autumn.
Thinning out the crown is enough
Although the ball trumpet tree is a very pruning-friendly fellow that won't even bother you if you cut off its crown, regular pruning or rejuvenation is basically unnecessary. Especially with older trees, it is sufficient to simply thin out the crown from time to time and cut out dead or diseased trees. However, you should be careful not to simply shorten individual shoots - because the ball trumpet tree tends to react to such a measure by developing unsightly spider veins. Otherwise, new growth occurs quite quickly, even after a more radical pruning.
Getting young trees into shape
If you bought your ball trumpet tree from a tree nursery, you will certainly have been advised to prune it back after planting - if this has not already been done by the specialist himself. Such a cut can actually be very useful for young trees, as it allows the crown to grow more densely. In addition, the subsequent leaves often become larger. But the same applies here: Don't just shorten individual branches, but carry out a courageous pollard trimming.
Do not cut the ball trumpet tree in autumn
Since the globe trumpet tree is quite sensitive to very frosty temperatures, you should never cut it in autumn - otherwise it could happen that the tree has no reserves over the winter and simply freezes away completely. Instead, the frozen shoots can also be removed in spring, although pruning should ideally be carried out on a warm day between February and April. A late pruning will not harm the ball trumpet tree, after all it only sprouts very late.
Tip
After a hard winter or a violent storm, it may happen that you have to cut down your trumpet tree completely. However, this does not harm the tree as long as you prune the crown above the grafting point.
