Question
QUESTION: Quite suddenly, the 6'+ tall ficus plant in the lounge at work has started to emit a nearly overpowering musty smell. Did we over-water it, or what?   It's much too large for us to try replacing the soil. Is there a fungicide we could apply to control the mold?  Or should we cover the surface with lime?  It's a splendid plant.  We would hate to lose it, but some of us are worried because we have allergic reactions to mold.

ANSWER: Hi C.J.,

There are several possible causes of the unpleasant odor. One would be poor quality soil. The second would be some kind of food substance being poured into the soil. This is particularly likely in a lounge or eating area. A third possibility is that stagnant water is building up in the bottom of the plant's container.

There is not much you can do about poor quality soil, although this is the least likely possibility. Sometimes the addition of lime will resolve the situation. Otherwise, you may have to remove the plant.

Many people honestly believe that they are helping a plant by giving it coffee or soda. Others think that pouring beverages in the soil is like pouring it in the ground outside. If you suspect this going on - do you see any evidence of food substance or mold growing on the surface of the soil? - then try to stop it.

The container holding the Ficus should have drainage holes so that excess water drains out and does not stagnate. In addition, it is important for the top inch or so of soil to dry out in between waterings. If there are no drainage holes, then you will have to find a way to create them.

If you suspect that the soil has been kept too moist, you can add some lime to help mask the odor. However, you must allow the soil to dry out more or the roots will rot. Perhaps this is happening already.

If mold (a fungus) is present, it will probably be visible on the surface of the soil. If so, scrape it off and all loose soil above the roots and discard it. New mold may appear, so you may have to scrape it off repeatedly until you have successfully removed all of the mold spores from the soil. There are commercial fungicides available, but they are potentially hazardous to use. Look for one that can be applied as a soil drench.

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



---------- FOLLOW-UP ----------

QUESTION: The soil I used when potting this plant was Miracle Gro Potting Mix.  Was that a mistake?  There's no mold detectable on the surface of the soil, though when I turn the soil a bit, the musty smell does get stronger.  I blended some lime into the top inch or so, though I'm concerned about adding too much and perhaps harming the plant. The soil already seems pretty dry, as far down as I can test it using a long, thin bamboo support. When I tilt the large plastic container it's in, I see that the bottom of the container and the plastic saucer it sits in are just slightly damp. There's no standing water apparent. What may be more worrisome is that roots are beginning to protrude through the drainage holes I'd drilled into the container when we first shifted the ficus from its previous container into this one.  It's been in this container for a couple of years now and has grown and spread out quite a bit.  Maybe the best thing to do would be to transplant it to a larger pot?
ANSWER: You seem to have covered all of the possibilities except that something was poured into the soil that should not have been. Unless someone witnessed the event, there is no way to tell if that happened.

The appearance of roots through the drainages holes is quite normal and is not an indication that the tree needs a larger pot. How often is the tree watered and how much is given each time? If the soil is staying too moist, you may be smelling the odor of rotting roots. Also, is the water quality good enough to drink? If not, you should use filtered or distilled for the tree.

If the roots are healthy, then the only treatment I can suggest is to take it outside and then flush lots of clear water through the soil to flush out any foreign substances that may have been introduced.

~Will Creed


---------- FOLLOW-UP ----------

QUESTION: Sorry about the repeat messages.  I got confused by the message from the site.  Anyway, the plant is watered once a week, with about 3/4's gallon of water.  The water is from the tap, but is good enough to drink.  I'll try switching to bottled water, though, just to see if that helps. This last time I may have not waited long enough between waterings. The college where I teach is not in session over the summer, so I'm here at random, so it's harder to keep to a schedule. The plant is in the lounge on the third floor, and there's no elevator, so it would be quite a project to move it outside.  If necessary, would it help to take the plant out of the pot, trim back any rotting roots, and repot it?  Or would that most likely kill it?

Answer
Three-quarts of water per week seems like a lot, but I don't really know the size of the tree and other environmental factors. Root rot could be the problem although it is pretty hard to do that with a well-established Ficus tree.

College? Students? A prank or just random teen-aged behavior? Just speculating here as I belong to a 19 year old college student myself!

You can take the plant from its pot, but that may not be so easy either. Do it just before you are ready to water it. The rootball should be damp at that point, but not wet. The roots should be firm and light colored. If not, then root rot may be the problem.

Unless it is terribly potbound, I wouldn't repot it. You might consider removing the outer layer of roots and soil from the bottom and side and replacing it with some fresh soil in the same pot. If the roots are healthy, pruning them back will not harm the plant.

~Will Creed