Plant Doctor Archive

Berries for Idesia

I HAVE an idesia tree that I planted about eight years ago. I've been waiting for it to produce its lovely red berries and this year at last it looked like it was going to do so. But they all shrivelled up and died while they were still green. The tree seems to be healthy as it grows well. Can you help?

Idesia polycarpa is often called the wonder tree as in late summer it can bear masses of waxy berries, like bunches of bright red grapes, that remain on the tree long after the leaves have dropped off for winter. While most other tree species have both male and female organs in the same flower, the tricky thing about idesias is they usually come as either a male or female tree. If yours is male you're never going to get berries, and if it's female you will only get berries if the flowers are fertilised by pollen from a male idesia. From what you say it sounds like your tree is a female and the berries fail to develop fully because they are not being fertilised by a male.

Some nurseries solve this sexy problem by selling idesias that have both male and female shoots grafted on to the same rootstock, so ensuring a reliable crop of berries. However, there are probably also a lot of seed-raised idesias for sale out there and there's no way of knowing what sex these are until they flower and, as you have found out, that can take several years. Unfortunately, the only thing you can do is plant a male mate for your lonely female, or one of the grafted types, but you really need a large garden for two idesias as they get quite large.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.