Question
I have a yucca that I've had for five years.  It's about 160cms now and was a beautiful plant until recently.  Nothing about its situation has changed - it has been in the same picture window (floor to ceiling glass) for the last two years.  It gets as much light as it's possible to get in Surrey in January!

Various leaves are turning on the plant.  I've been getting a lot of brown tips - and by tips I mean the bottom five to six inches of the leaf turns brown and shrivels.  Some of the larger leaves are starting to get a yellow tinge through the middle with dark spotting here and there.  These are mid to lower leaves.  It's a very 'bushy' plant.

I've been removing the brown tipped leaves.  There is some new growth at the top of the plant but I'm worried there's something I'm missing on the rest.

I always water my yucca into the tray underneath the pot so the plant takes as much water as it needs - I pour any excess off after about an hour.  At the moment I water once every 5 days or so.  I liquid feed once a month in the winter.  

The plant is in a large terracotta pot - close to the largest size you'll easily get in the garden centre -  with one or two roots appearing through the drainage hole.

Any suggestions about what I can do to rescue it?

Answer
Hi Angela,

Without a photo, it is difficult for me to evaluate the degree of the leaf-tipping problem. A certain amount of leaf-tipping and lower leaf loss is normal as a plant ages.

Nonetheless, there are a couple of things that you are doing that are not good for plants generally and your Yucca specifically.

Watering from the bottom is not a good practice. In part because it is hard to determine when the plant has wicked up an appropriate volume of water. More importantly, minerals in the water are also wicked up and concentrated in the soil around the roots. Over time, these mineral concentrations can become toxic to the roots. The use of plant food simply aggravates this problem because plant food is composed of minerals.

If you water from the top, then you know just how much to add by stopping when you see a little water trickle through the drainage hole. In addition, top watering flushes excess minerals through and out of the soil with each watering.

If your local water is on the hard or alkaline side, then use filtered or distilled.

Your pot may also be too large. The diameter should be about 25-30 cms. If it is significantly larger than that, then the soil may be staying too moist and slowly rotting the roots.

Please let me know if any of this is unclear or if you have any additional questions.

Visit my website at  www.HorticulturalHelp.com

If you would like to e-mail me some photos, I may be able to provide some additional insights.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]