Plant Doctor Archive

Yellow leaves on michelia

I PLANTED a 1m high Michelia 'Bubbles' about four weeks ago. Some of the leaves nearest the trunk are turning yellow and dropping off. The soil is quite wet and consists of a lot of clay and rocks, though we added a lot of compost when we planted it. Can you suggest what we can do about the leaf yellowing?

LEAF yellowing shortly after planting is often a result of the root system being either too dry or too wet. Recently planted shrubs can easily suffer from drying out until new roots grow out of the nursery mix into the surrounding soil.

Scrape away some soil from above the root system and check to see how much moisture there actually is around the roots. If the mix around the roots is dry, you'll need to give it about a bucketful of water every couple of days until there's plenty of rain to take care of the job for you. If the soil is very wet or the hole is waterlogged, then lack of drainage is the problem - a hole dug in heavy clay can sometimes just fill up with water and the new plant will "drown". If this is the case, dig a channel to drain water away from the hole or dig up your michelia and replant it, this time on a mound of good soil and compost raised 30-50cm above the normal soil level so excess water drains away.

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