How Dry Should Ficus Be

by George Buehler

NOTE: What I am reporting below should be considered thoroughly before you try what I did. Everyone's situation is different and what worked for me may not work for you. I am neither recommending nor suggesting that you try what I did. I am just reporting what I found - ED

In the December 2004 newsletter, I reprinted an article by Dave Bogan (Editor of the Greater Evansville Bonsai Newsletter) on Growing Stronger Ficus. In that article Dave stated that ficus 'may not' need as much water as we think. I reported in our January 2005 newsletter that I had in past years made sure that my two ficus were kept continually moist when they were in the basement under lights for the winter. However, this winter I decided to run a mini experiment based on Dave's article. This article is a report on that brief (and admittedly small sampling) experiment.

In the past, both ficus would lose leaves all winter long and what leaves that remained were a dull yellow to yellow-green color. No matter what I tried (rotating, periodic fertilizing, heat, air movement, etc.) they always looked bad. When I brought them out of their winter hibernation, it would take quite a while for the leaves to 'green up' and the trees to start actively growing. Based on what I had previously read I was doing it correctly and I just assumed that this was part of the problem with the ficus. I am by no means an expert on ficus; and, perhaps on what I am reporting below, those more experienced with ficus can jump in and offer some more information.

I know, based on past entries in my bonsai journal, that ficus don't like changes. Ideally, they would be most happy growing in a greenhouse all year (probably the hotter the better). Since I don't have a greenhouse (something on my wish list!), the ficus have to be moved to my basement when the weather gets cold. In the spring they are moved in and out (depending on the temperature). I keep them inside until the weatherman says the temperature will be above 50 F at night. No matter what, these changes in location do cause some leaf drop. But this is not the type of leaf drop I was seeing when I had my trees in the basement for the winter.

I originally thought that I had brought in scale on one of the plants and it would spread to the other. However, this year I thoroughly inspected the trees prior to moving them in and sprayed them with insecticide last fall. I would periodically inspect them to determine if there was any 'honeydew' on the leaves - indicating the presence of scale. I could find no evidence this past winter of any scale.

After reading Dave's article, I decided to try an experiment. One ficus (a Ficus benjamina in a root over rock style) I purposely let dry down more than I had in past years. I had all kind of trepidations on how much to let it dry. I ended up using the chopstick method of determining when the tree needed water. In the location and environment that my tree was in, I determined that the tree needed watering every 10 to 12 days. The second ficus (a willow leaf, Ficus narrowfolia in a forest planting) was watered as I had in the past - every Saturday.

When either was watered, water out of the same container was used and water was added until it started showing up in the drain pan. I did use fertilizer (Dyna-Gro at 1/2 teaspoon per gallon of water) on both throughout the winter. Due to the longer intervals between water additions, the bejamina actually received less fertilizer than the willow leaf. I couldn't figure out how to fertilize both at the same frequency levels without shortening the time interval between watering for the benjamina. As you will see below, this wasn't a problem.

Both trees were placed on the same shelf, with the same number of lights. They both were also rotated 90 degrees every Saturday to ensure adequate light exposure. Based on information gathered from Gene Sewell, I had modified my light source from that of last year. For each 48 inch by 24 inch shelf, I added an additional set of fluorescent light (for a total of 6 four foot bulbs @ 3200 lumens per bulb). Since both trees were on the same shelf, I believe that this was a "non-factor" in the experiment. Although I did rotate the trees, they did stay in the same location on the shelf.

I started moving my tropicals out of their winter storage area to a screened in porch on April 4, 2005 (based on my bonsai journal) since the temperature that day was in the mid 70's. Both trees were put side by side each time they were moved. I started exposing the trees to dappled sun about two days later. Of course, our weather changed back to our normal Ohio valley spring time and I moved them back inside when the temperature was below about 50-55 F. When the temperature rose back above that level, the trees were returned back outside. Once again, since both trees were exposed to the same routine, same temperature and same sunshine, I cautiously call this also a "non-factor". I went through my books and searched the internet to see if I could determine if either of the species of ficus was more susceptible than the other to temperatures, but could find nothing.

As I started exposing the trees to more direct sunlight, I had to shorten the time between watering the benjamina. It is still being watered less often than the forest. As the temperature rose to the mid to upper seventies, the water interval was increased to the normal daily routine for each, since both were in the full sun at this time.

During the winter storage, the forest (which was watered more often this time) lost a lot of leaves. It also lost more leaves when it was moved outside. In the past, it generally recovered after sitting outside for three or four weeks. The root over rock ficus also normally suffered the same symptoms and the same recovery time. Both trees started greening and developing new leaves when the temperature started warming and responded more quickly when the night temperature was warm. If the nighttime temperature was cool (i.e. less than 60 F) for several nights in a row, the new growth slowed. This apparently is normal for ficus.

This year, the forest started losing more leaves than in the past. As a matter of fact, it almost completely defoliated itself [See Figure 1]. I noticed that as a limb lost all its leaves, there was a period of about 3 to 5 days before there were signs of new leaf development. I originally thought that I had sent the forest to the happy bonsai in the sky place. After a period of time (about six weeks), the tree was covered with mostly new leaves.

The benjamina lost a few leaves when it was placed outside but nothing like it did in the past. In fact as soon as it started getting full sun and the daytime temperature started increasing, it started developing new leaves [See Figure 2]. I did apparently lose a branch or two which is causing a design problem but overall the tree looks extremely good - much better than in the past.

There is also one additional point to report - this is about the soil. For my tropicals, I had always used a commercial soil that contained a lot of organic material and was a small grit (about 1/8" in size). In order to get the root over rock ficus to dry down quicker, I transplanted it on February 23 (yes I know very risky) to a quicker draining soil with less organic matter in it. I did not root prune, only took it out of the pot it had been in, removing the old soil, and planting it in the new type soil. After it recovered from the transplant shock (about two weeks), the dry down time was shorter than when the soil with more organic matter was used. This again was what I wanted - to keep the tree drier. The dry down time was shortened to 8 to 9 days (down from 10 to 12 days). Using the chopstick, after the 8 to 9 days, the wood was just barely moist with the new soil. This was the same for the old soil after 10 to 12 days. Comparing this to the forest soil, the chopstick was moist every Saturday when it was watered.

What can I conclude from all this? I believe there are a couple of important points:

• The ficus does not need as much water as I originally thought in the winter - Dave Bogan was correct.
• The type of soil for tropicals needs to be a free draining soil with perhaps less organic matter in it.
• You have to know your conditions. What works for one situation (like mine), may not work for yours. Read the information carefully, consider what your situation is, and then make your decisions.

I have transplanted the forest this summer and used the soil with less organic matter in it. I also plan on doing some major pruning to shorten the height of the forest and to try to develop more ramification. This winter, I will again repeat the experiment letting both trees dry down more and report the results next year.

 

If anyone out there would like to comment on this experiment, send me a note and I will put your comments in the next issue.