Plant Doctor Archive

Yucky-looking yucca

I HAVE two yucca plants that are both suffering from some sort of ailment. The leaves started going brown at the tips, then they started turning yellow and shrivelling, eventually collapsing. One yucca produced a slight smell, so I sprayed it with a fungal spray, which cleared up the smell but the leaves continued to yellow. I thought they might be suffering from root rot, so I repotted them in a freedraining mix. The leaves continued to yellow. A lady at my local garden centre said they were probably suffering from mites. I sprayed with a miticide, but still the leaves continue to yellow. Do you have any ideas?

THE blackish-brown damage on the leaf tips in your photo suggests the problem is more likely one of too much water and/or fertiliser than mites or fungal disease. As an indoor pot plant, yuccas thrive on neglect. Allow them to get quite dry between waterings, especially in winter. And when you do water in winter, only give them a small amount - don't soak the whole mix.

The rather soft look of the foliage also implies they need more light. Expose them to as much sun as possible, even to the point of putting them outside to sunbathe every now and then, but be careful to acclimatise them to sun gradually so they don't get sunburned. And don't fertilise them at all unless they look extremely starved - that is, the whole leaf has an overall yellow appearance.

If all this sounds too hard, you could always move them outdoors or plant them in a sunny well-drained spot in the garden, they grow well outdoors in most warm northern parts of the country with a minimum of attention.

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