by Dave Bogan

Dave has been the editor of the Greater Evansville Bonsai Society for about 10 years. He has been actively pursuing the art of bonsai for about 16 years. He has over 300 trees in his collection. He states he is an avid believer in bending the rules in bonsai and continues to experiment with different techniques to improve his bonsai. - ED

Ficus are my favorite and the most abundant species in my bonsai collection. Having been attracted to ficus many years ago, they now total over 50 trees comprised of 7 different species. Yes, nerrifolia are by far the majority but, most Ficus can be treated the same. Most bonsai enthusiast have at least one. I, as well as most enthusiasts, have read the books which tell us to treat them as a typical tropical bonsai. After growing Ficus for well over 10 years, I have come to the realization that they are different than most tropicals, a little unusual in their growth pattern and have several species specific issues when it comes to good growth. In past years, I followed the books and would repot a nerrifolia after one or two year's growth. I was amazed at the root growth or maybe I should say lack of root growth. So, I started to experiment and talk to other ficus lovers. Here are a few issues you may want to consider if growing ficus.

Sun & Temperature:

Ficus love all the sun you can give them. I mean ALL day direct sun. None of this "protect them from the hot afternoon sun" as with other species. Sure, they will get by with lower light or cool temperatures but for rapid and good growth, they must have all the light and heat you can give them. If you watch them in early spring, they show little if any growth until the day temperatures stay above at least 75 and the nights are above 60. I would venture to say in our area, a ficus's growing season is only about 90 days. If you give them less than full sun, their strong growth season will be even less. To give you an idea how heat increases growth, I experimented with a couple of my nerrifolia this fall. Setting on their benches in early Sept., their growth had almost stopped or at least slowing down considerably from the past months. I moved them into the greenhouse. At this time of the year, my greenhouse was reaching a day temperature of 100 - 105 and nights above 70. I'm happy to say these ficus responded with strong new growth. Remember tropicals in their native areas are used to extreme heat and more direct sunlight. Stop and think, have you ever laid on the beach in Florida? You will tan but probably burn a lot quicker than here in the Midwest due to the more direct sun light.

Soil:

It took me a while to agree, but after several test trees, I found my ficus grew a lot better in fast draining soil. I now use a large particle mix and do not include any humus or other additives.

Water:

A huge but confusing factor here in the Midwest. When I first started with ficus, I felt they needed a lot of moisture in the soil - wrong. I'm now a firm believer that ficus are almost a succulent type plant. They hold a tremendous amount of moisture in their roots, trunks and branches. As mentioned above, I now use a fast draining soil mix which will not retain a lot of moisture and I allow my trees to dry out between waterings.

Here’s the rub - Ficus can be very finicky. All of us have seen them defoliate at the drop of a hat. This is all due to not liking fluctuations in light, temperature or moisture. The real key here is to avoid the fluctuations. Probably the hardest one to maintain a delicate balance with, is the moisture content. As mentioned, I allow my trees to become slightly dry before watering. In reality here in the Midwest, there is probably 24 and 48 hours between a slightly dry soil and the time that they start to lose moisture content inside their structure. It's when they start to lose internal moisture that they will drop leaves. This is a natural reaction. Leaves transpire moisture, and the plant will drop some to maintain a moisture balance. Even after this period, ficus will generally go a long time before they actually die. They can live off their internal moisture reserves for a long time. Yes, they will probably shut down all growth and eventually drop all their leaves, but this takes a while. How many times have you heard someone say a ficus was dead but, after scratching the bark you found live green tissue? They may look bad, but they're still alive.

Root Growth - Try this experiment using two similar size, age and condition trees:

Tree #1 - Transplant in late June. Use a standard soil mix (typical deciduous mix). Trim roots. Make note of the quantity, size and length of the root system. Water daily (keep moist) and fertilize the same as all your other trees.

Tree #2 - Transplant in late June. Use a heavy grit fast draining soil mix. Trim roots as in tree #1 and again make note of the root system. Water only when it appears dry but, fertilize as usual.

Now, wait 2 years. Remove both trees from their pots (late June), and wash off all the old soil. Inspect the root systems. You will probably note that tree #1's root system has not changed drastically. There may be a few long roots but no real ramification, and many of the roots cut previously are still stubs with no growth. Now tree #2. I will almost guarantee you will have 2 - 3 times the root growth plus better upper growth.

Many times, we are fooled by ficus growth. I have had trees (after repotting) grow great. Very nice upper growth, even to the extent I was pruning them every week or so. But come repotting, they have exhibited very little new root growth. Confusing??

Ultimately, ficus don't require a huge root system and can live with very few roots, thus their ease of transplanting and their longevity. I firmly believe ficus can absorb moisture and nutrients no matter how large their root system is. I have seen ficus totally root bound in nursery containers, root bound to the point that they actually burst the container. These plants were setting out in direct sun and were growing fine. In fact, I purchased just such a tree. This tree was over 6' tall in a 10 gallon nursery container. It was totally root bound and bursting the pot, but it had a decent amount of foliage and looked to be very healthy. Upon getting it home and inspecting the root system, I found hardly any small roots. All the roots had grown large and most where fused together, to the point that I doubt if there was more than 1 gallon of soil in the entire 10 gallon container. With this lack of soil, I'm still amazed how the tree stayed alive let alone grew. A little worried, I simply potted it up into an even lager container (15 gallon) with large grit soil surrounding the existing root system. After allowing it to grow only one year, I pulled it out. I was very happy to see that in the area of the new large grit soil I had numerous small roots forming. Since it was now in very good health and condition, I decided to repot it (July). Using a large saw, I proceeded to cut off over 90% of its lower root mass - to a depth of only 3" and potted it in a large container with fast draining large grit soil. The top was cut back severely to only 7 bare stubs resulting in a new height of about 14". In the first year, the growth was fantastic and created a full canopy. The growth was so full you could not see any of the inner structure or cut areas. In January, while in the greenhouse, I thinned it out completely-down to the branches I wanted to maintain (click here). By June, it was totally full again. Amazing growth. With all its abundant growth, I again transplanted it in early October. Yes, I said October - in the greenhouse which was still reaching 90 - 100 degrees during the day and 70 at night. The root system was expanding very well and it had very lush & abundant top growth. After a slight root & top trimming (trimmings filled a 2 gallon pail) , a new pot and fresh soil, it now is doing great in the greenhouse - pushing new growth in Nov. with out a single leaf dropping.

To further my theory, I firmly believe ficus will tolerate and grow in about any condition but, if we want additional strong growth and size, we must change our ways. If in moist heavy moisture retentive soil, it will obtain what it needs to grow, but roots will not form as well. I firmly believe the plant doesn't send out roots because it has what it needs. With the fast draining soil, it is fooled into searching for nutrients and thus sends out a multitude of roots.

If we study ficus in the tropics, they grow very quickly and send out a multitude of searching roots. These roots have been known to grow hundreds of feet searching and encompassing everything they grow over. I have also been told in S. Florida, if wired, the wire must be removed in only 1 or 2 weeks or it will be February after hard pruning and thinning severely damaged and scared. So, if you want growth close to what practitioners obtain in the tropics, you need to adjust how you treat them here in the Midwest.

If you want a nice tree, I definitely recommend you consider a ficus - if you can maintain it properly. In the case of the large nerrifolia tree I mentioned here in this article, it was grown from a cutting 10 - 12 years in a nursery container. Can you name me any other trees which can be grown to a trunk base area of over 16" x 6'+ tall, then be severely pruned, potted and be a nice tree within 3 or 4 years? I have a collected elm in my collection which I've been training for well over 10 years. Sure, it looks nice but, considering the time difference, there is no way it could have matched a ficus at 3 - 4 years into training.