Issue: October 12th, 1998

Every autumn Ficus leaves drop

Help me please. Every fall, in late September, my Ficus drops many of its leaves. I don't change my watering schedule. I don't move the tree. I don't do any thing different, still every year it drops its leaves. What causes this and what can I do to prevent it?

Your guess about changes is probably right. The change you didn't mention is your furnace. Does it come on for the first time each year shortly before the leaves began to drop? Many plants don't like changes, like people. Ficus doesn't like changes in humidity. When the weather turns cold and you close the house, then fire up the furnace, the air dries significantly. That is even true here in New Mexico where the air is always dry. However, the furnace dries it even more.

So, the solution is to do something to maintain the humidity. Misting the plants once a day does little to raise the humidity for a long period. However, placing many plants together in a grouping allows them to collectively raise the humidity. Deflecting any furnace air from blowing directly toward plants also helps. In some cases, it may help to place curtains or ornamental screens between the plants and the source of furnace air. This allows a lower temperature near the plants, yet not low enough to cause damage. This lower temperature air will have a higher humidity. Also, it is subject to less air exchange with the drier air and retains the moisture from the plants longer than the rest of the room.

Frequent misting will help, but grouping the plants will do more. It also helps to place the plants over dishes of small rocks in which water is kept at a level below the bottom of the pots. Don't let the water draw from this dish into the pot because as water evaporates, calcium, sodium and other salts from the water will accumulate. In high concentrations, these are harmful to the plants.

Although I have spent a lot of this column discussing humidity, it is also wise to check for insects. Although the Ficus may have been in the same location for a long time, you may have brought plants from outdoors into the home and placed them near the Ficus. In bringing the other plants inside from outdoors or from the nursery, you may have also brought insects inside. These insects may cause the leaf drop.

A good inspection for insects before bringing in new plants is a good practice. However, it is wise to isolate plants from the nursery or from outdoors from the plants which remained indoors all summer. These new plants may be infested with the eggs of insects, and these eggs may not be visible when the plants are inspected. By quarantining these plants for a while, you give any insects or other problems a chance to become apparent before they can spread to other plants.

If you do find insects, take them to a knowledgeable nursery professional or to your local Cooperative Extension Service Office to identify the pest. You can also get advice regarding appropriate treatments, organic or chemical, to eliminate the problem. Remember, indoors you must be very careful which insecticides you apply. This is even true of the organic insecticides. Some of these are quite toxic to humans or cause allergic reactions. Select a product labeled for use indoors and then follow the directions on the label to maximize effectiveness and to reduce hazards to you and your family.

Then, enjoy your indoor garden through the fall and winter when healthy plants make the season much more enjoyable.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!