Beginner Gardening: Re-potting Bodhi Tree, what size pot for growth?, 0 by tapla

tapla wrote:
I tried to answer all your questions and offer advice yesterday, but after at least a half hr into the post, it disappeared. That's one thing I think Dave's should fix. It's very frustrating. I also tried to edit out the underlines on the post above, but when I click on the edit link, all I got was an empty box.

First, the mix I use is equal parts by volume of screened Turface, fir bark, and crushed granite (grower size grit, #2 cherrystone, or MannaPro poultry grit).

Unfortunately, now is not a good time to repot tropical. Ficus should be repotted in the month prior to their most robust growth, which would be in June if you live in the US. Plants have natural rhythms, and it's best to work with those rhythms instead of against them. It's better for the plant and makes for growers happier with the results of their efforts. Your plant will recover much faster from the work, leaving it much less susceptible to insect infestation and diseases if you do any major work in June.

1) If you've changed the soil, wait about 2 weeks to start fertilizing. Roots will colonize the soil mass faster when they are suffering a mild deficiency. After 2 weeks, start fertilizing with the 9-3-6 - it's about the best choice you can make as your 'go to' fertilizer for your containerized plants.

2) Ideal pH for your Ficus is between 5.0-5.5. If you can find a friend who has a reverse osmosis water system, use that water. Air conditioner or dehumidifier condensate is good as well, as is rain water. If your soil is high in dissolved solids, it's very important that your soil allows you to flush the soil thoroughly and regularly. Nutrient ratios in the soil solution quickly become skewed, especially if you're not using a fertilizer with a ratio that closely mimics that at which the plant actually uses the nutrients.

3) Trees won't learn to hold themselves upright. The reason yours wants to flop over is insufficient light. The remedy is twofold. More light and a pruning of the top back to a branch that lends itself to being trained to the vertical. Branches growing vertically send chemical messengers to the rest of the plant. The plant recognizes this signal as a call for more photosynthate. The tree will quickly recognize your new leader as a stronger energy sink than any other branch and provide it with a larger measure of food. The shortened trunk will be better able to support itself and your tree won't droop. It won't have a straight trunk, but I'm of the crowd that thinks trunks w/o movement (that are straight) are boring.

4) Sounds like a good plan, and a propagation mat under the pot is a good move. Try overturning a cardboard box or plastic tub so the bottom is open and it covers the mat. Cut a hole in the top (the former bottom) just large enough for the pot to slip through and rest on the prop mat. This will raise root temps 10-15* above ambient.

5) About pot size:

Choosing an Appropriate Size Container
How large a container ‘can’ or ‘should’ be, depends on the relationship between the mass of the plant material you are working with and your choice of soil. We often concern ourselves with "over-potting" (using a container that is too large), but "over-potting" is a term that arises from a lack of a basic understanding about the relationship we will look at, which logically determines appropriate container size.

It's often parroted that you should only move up one container size when "potting-up". The reasoning is, that when potting up to a container more than one size larger, the soil will remain wet too long and cause root rot issues, but it is the size/mass of the plant material you are working with, and the physical properties of the soil you choose that determines both the upper & lower limits of appropriate container size - not a formulaic upward progression of container sizes. In many cases, after root pruning a plant, it may even be appropriate to step down a container size or two, but as you will see, that also depends on the physical properties of the soil you choose. It's not uncommon for me, after a repot/root-pruning to pot in containers as small as 1/5 the size as that which the plant had been growing in prior to the work.

Plants grown in ‘slow’ (slow-draining/water-retentive) soils need to be grown in containers with smaller soil volumes so that the plant can use water quickly, allowing air to return to the soil before root issues beyond impaired root function/metabolism become a limiting factor. We know that the anaerobic (airless) conditions that accompany soggy soils quickly kill fine roots and impair root function/metabolism. We also know smaller soil volumes and the root constriction that accompany them cause plants to both extend branches and gain o/a mass much more slowly - a bane if rapid growth is the goal - a boon if growth restriction and a compact plant are what you have your sights set on.
Conversely, rampant growth can be had by growing in very large containers and in very fast soils where frequent watering and fertilizing is required - so it's not that plants rebel at being potted into very large containers per se, but rather, they rebel at being potted into very large containers with a soil that is too slow and water-retentive. This is a key point.

We know that there is an inverse relationship between soil particle size and the height of the perched water table (PWT) in containers. As particle size increases, the height of the PWT decreases, until at about a particle size of just under 1/8 inch, soils will no longer hold perched water. If there is no perched water, the soil is ALWAYS well aerated, even when the soil is at container capacity (fully saturated).

So, if you aim for a soil (like the gritty mix) composed primarily of particles larger than 1/16", there is no upper limit to container size, other than what you can practically manage. The lower size limit will be determined by the soil volume's ability to allow room for roots to ’run’ and to furnish water enough to sustain the plant between irrigations. Bearing heavily on this ability is the ratio of fine roots to coarse roots. It takes a minimum amount of fine rootage to support the canopy under high water demand. If the container is full of large roots, there may not be room for a sufficient volume of the fine roots that do all the water/nutrient delivery work and the coarse roots, too. You can grow a very large plant in a very small container if the roots have been well managed and the lion's share of the rootage is fine. You can also grow very small plants, even seedlings, in very large containers if the soil is fast (free-draining and well-aerated) enough that the soil holds no, or very little perched water.

I have just offered clear illustration why the oft repeated advice to ‘resist pottting up more than one pot size at a time’, only applies when using heavy, water-retentive soils. Those using well-aerated soils are not bound by the same restrictions. As the ht and volume of the perched water table are reduced, the potential for negative effects associated with over-potting are diminished in a direct relationship with the reduction - up to the point at which the soil holds no (or an insignificant amount) of perched water and over-potting pretty much becomes a non-issue.

More about Ficus culture in general:

The Ficus genus
with more than 800 known species, is undoubtedly an extremely popular choice as a containerized tree. It tolerates the "dryer than desert" conditions actually found in many or most centrally heated homes reasonably well, and is endowed with a natural genetic vigor that makes it easy to grow. There is however, much myth and misconception regarding the care of this plant and the reasons it reacts as it does to certain cultural conditions. I would like to talk a little about the plant and then offer some specific information regarding its culture. I will primarily address Ficus benjamina - the 'weeping fig', but the commonly grown Ficus elastica - rubber tree, has the same cultural preferences. In fact, we can virtually lump all the Ficus species commonly grown as houseplants into a single group in all areas except light preferences. We need to make allowances for some of the fig species that won't tolerate direct sun as well as benjamina and elastica, and we may as well expand that exception to the variegated cultivars of benjamina and elastica as well.

Ficus benjamina
is one of the species of Ficus commonly referred to as a strangler fig. It often begins its life in duff, in the crotch of a tree, or high on a branch as a seed deposited in the droppings of a bird or other tree-dwelling animal. After the seed germinates and as it grows, it produces thin aerial roots that often dangle in the moist air or attach themselves to the host trunk, while gaining nutrients and moisture from the air, leaf litter, and the bark of the supporting tree. It does not actually parasitize the plant it grows on, it only uses it as support. This relationship is termed epiphytic, or the tree an epiphyte. Those familiar with the culture of orchids and bromeliads will recognize this term.

After the aerial roots have formed and extended, and when they finally reach the ground, the tree begins a tremendous growth spurt, sending out more roots and developing a dense canopy that eventually shades out the supporting tree at the same time the roots are competing for nutrients in the soil and compressing the trunk and branches of the support tree to the point of stopping sap flow. Eventually the supporting tree dies and all that is left where it once stood, is a hollow cavity in the dangling Ficus roots that have now thickened and self-grafted to become the trunk. It is easy to see how many of the trees in the Ficus genus have come to be called by the name 'strangler figs'.

Roots and soil
The roots of some Ficus species are so powerful they can destroy concrete buildings or buckle roads, and can be measured in miles as they extend underground in search of water. When we consider the young tree and its ability to obtain sufficient moisture from just the surrounding air and bark surface of the support tree by way of aerial roots, we can draw an important conclusion: All species of Ficus prefer well-aerated and fast draining soils. In this regard, they are actually no different than any other tree you would endeavor to grow in a container, so try always to use a soil that guarantees an ample volume of air in the soil and excellent drainage for the intended interval between repots. This can be accomplished by using a soil whose primary fraction is comprised of large particles (like pine bark) combined with ample volumes of perlite or other inorganic ingredients like Turface, pumice, Haydite, crushed granite, or others. I grow all my Ficus in a soil mix consisting of equal parts of pine or fir bark, Turface (a calcined clay product), and Gran-I-Grit (crushed and screened granite). To be fair, I will add a qualifier here: the cost of the potential for superior growth and added vitality when using these fast (draining) well-aerated soils comes in the form of you needing to be prepared to water more frequently as the soil particle size increases. Roots are the heart of the plant, and the rest of the plant can do nothing without the roots' OK - the top just THINKS it's in control. Take care of the roots, and if your other cultural conditions are favorable, your plants will thrive.

Before I go on
I would like to say there is a very important relationship between your choice of soil, your watering habits, and a very common and serious problem that too often goes completely undiagnosed. That problem is a high level of soluble salts in the soil. When we choose soils that hold water for extended periods, we put our trees at risk for the fungal infections that cause root rot. Reasoning tells us that to avoid the root rot issue, we should not water to the point of soil saturation; rather, we often feel that watering in sips to avoid the specter of root rot is the wise alternative. This strategy though, puts us squarely on the horns of a dilemma. If we don't/can't water copiously on a regular basis, the soluble salts, i.e.,all the dissolved solids in our tap water and fertilizer solution accumulate in the soil. As the level of salts in the soil increases, the plant finds it increasingly difficult to absorb water and the nutrients dissolved in water. If the salt level gets too high, it can actually 'pull' water OUT of cells in exactly the same fashion that curing salt 'pulls' moisture from ham or bacon. This 'reverse osmosis' causes plasma to be torn from the walls of cells as they collapse, killing cells and tissue. The technical term for this is plasmolysis, but we more commonly refer to it as fertilizer burn. Fertilizer burn can occur whether or not we use fertilizer. The salts in our tap water alone, can/will eventually build to the point where water uptake is impossible, unless we actively take precautions.

Your soil is the foundation of every conventional container planting, and your choice of soils probably has a greater impact on your effort:reward quotient than any other single factor. Please take a moment to learn more about soils. My experience has shown that understanding how soils work and how to tell the difference between a good and a not so good soil is probably the single largest step forward a container gardener can take at any one time. Find more about soils here.


Watering
Ficus b. will tolerate dry soil quite well. Allowing the soil to completely dry; however, will result in undue drought stress and accompanying leaf loss, an expensive affair, considering the plant will call heavily upon energy reserves to replace lost foliage - reserves that might better have been directed to other functions and growth. If you wait just until the soil feels dry to the touch at the drain hole before watering, your tree will be free from the effects of drought stress. Soils feel dry to the touch when their moisture content is somewhere between 40-45%, but Ficus can still extract water from soils until moisture content drops to about 25-30%, giving you a 10-15% cush AFTER the soil feels dry. Use a finger or a sharpened wooden dowel stuck deep into the soil to check for moisture content. A wooden skewer or chopstick used in similar fashion is also a useful tool, and feeling the soil at the drain hole and withholding water until it feels dry there, is also a good way to judge. Water meters are rather ineffective, They actually measure EC (electrical conductivity). To illustrate: Insert a clean probe into a cup of distilled water. It will read 'DRY'. Add a little table salt of fertilizer, it will read 'WET'.

Though I try never to water my Ficus with cold water, I have never been able to verify that cold water has any negative impact on our houseplants ..... and I've asked a good number of horticulture's upper crust about any potentially negative effects, always receiving a shrug. The best way to water your Ficus it to apply water slowly until you estimate the soil is almost wet enough that water is about to appear at the drain hole. Wait a few minutes and water again so at least 10-15% of the total volume of water applied exits the drain. The first watering dissolves accumulated salts in the soil and allows them to go into solution. The second watering carries them out of the container. We already illustrated the importance of using a soil that allows us to water in such a manner without having to worry abut root rot. If you feel you cannot water in this manner without risking lengthy soil saturation and the possibility of root rot, your soil is probably inappropriate for the plant. Lest anyone complain at that observation, I would point out there is a difference between the growth and vitality of plants that are only tolerating a soil vs. the same traits in plants that appreciate (thrive in) a medium with superior properties.

More about soils as questions arise .... please ask!

Light
Although many Ficus begin life as an understory tree and are generally quite shade tolerant, most actually spend their life struggling through the shaded understory until they eventually reach the forest canopy, where they finally find full sun and can begin to come into their own. We should give Ficus all the sun they will tolerate. I grow all varieties of Ficus b. in full sun, and they tolerate it well - even some of the newer cultivars that are supposed to be extremely shade-tolerant.

I have often read anecdotal assertions that Ficus b defoliates at the slightest change in light levels (or temperature). I have found this to be only partly true. Any trees I have moved from a location with a lower light level to a brighter location have not suffered leaf loss (abscission). Instead, they have rewarded me with more robust growth and back-budding. If the change is reversed, so the tree is moved from high irradiance levels to a dimmer location, leaf loss is probable, but even then it depends on both the suddenness of the change and the difference between the two light levels. It might be interesting to note that trees that are being grown out, or allowed to grow unpruned, are most likely to suffer loss of interior leaves when light levels are reduced. Trees in bonsai culture, or properly pruned trees where thinning has occurred to allow more light to the trees interior are less affected.

Indoor supplemental lighting is a broad subject, but if you have the ability to provide it, your trees will definitely show their appreciation. Brighter light = smaller leaf size, shorter internodes, and superior ramification (finer branching), not to mention a marked increase in overall mass.

Temperature
Expect the most robust growth characteristics when the plant is kept in a temperature range between 60-80* F. Actual root temperatures above 90-95* should be avoided because they impair root function/metabolism and slow or stop growth. Temperatures below 55* should also be avoided for several reasons. They slow photosynthesis to the degree that the plant will necessarily call on stored energy reserves to power metabolism and keep its systems orderly. This essentially puts the tree on 'battery power' - running on its energy reserves. After exposure to chill and subsequent return to more favorable temperatures, the plant does not quickly recover the ability to carry on normal photosynthesis. The time needed for the plant to recover its normal photosynthesizing ability is more appropriately measured in days, than hours. Leaf loss can also occur as a result of exposure to chill, particularly sudden chill.

It is prudent to select a location free from cold breezes for your tree. Even short exposure to very cold draughts can cause leaves to abscise (fall/shed). The cool temperatures slow or halt the flow of auxin (a growth regulator - hormone) across the abscission zone at the base of each leaf petiole (stem) which allows an abscission layer to form and causes leaves to fall. Chill also stimulates an increase in abscissic acid (also a growth regulator - hormone) which is also a player in leaf loss.

Benjamina can tolerate temperatures as low as the mid-30s for brief periods if the exposure to chill is gradual, but it should be noted that even though there may not be any readily visible impact on the tree, the tree will always be in decline at temperatures below about 55* because of the impact on the tree's inability to carry on efficient photosynthesis. Sudden and large temperature drops can cause varying degrees of chill injury in the plant, caused by phenolic compounds leaking from cells, which shows up looking much like freeze damage. Severe injury could occur in plants that were growing at 80-85* and were subjected to sudden chilling to temperatures as high as 45-50*

Humidity
Benjamina's thick, leathery leaves with waxy cuticles help to limit moisture loss, making the plant suitable to a wide range of indoor humidity levels, even though it prefers humidity levels above 50%. When humidity levels are blamed for leaf loss or necrotic leaf tips and margins, it is likely the blame has been misplaced. Those pesky high salt levels in soils, most common in late winter, can make it difficult and in extreme cases impossible for the plant to absorb water to replace that being lost to the air through transpiration. The fast soils that allow copious watering, which flushes the soil of salts regularly are actually much more important/beneficial than maintaining ultra high humidity levels. Misting is very effective ..... For about 30 seconds. Forget the misting please, it is ineffective. For small plants, a humidity tray may marginally effective.

Fertilizer
I prefer any 3:1:2 ratio soluble fertilizer like Miracle-Gro 24-8-16 or 12-4-8, and I especially like Dyna-Gro's Foliage-Pro 9-3-6, because it provides all the essential nutrients in the approximate ratio the plant will use and in favorable ratios to each other. Alternately, a 1:1:1 ratio fertilizer like MG 20-20-20 is suitable. Because I use fast soils, I can fertilize at very low doses, every time I water. How YOU can/should fertilize is something we should discuss. It can change by season, and also varies based on soil choice and watering habits.

There is no question that in addition to offering greater potential for growth and vitality within the limits of other cultural factors, fast draining, well-aerated soils also get the nod for greatly increasing the grower�s margin for error in the areas of watering and fertilizing.

Defoliating
Leaf loss in Ficus is probably the cause of more conjecture than any other aspect of its culture, so even though I have mentioned it above, I will reiterate. Even though it is widely held that Ficus b. defoliates at virtually any cultural change, with changes in light and temperature most often cited, it is not so. The plant tends to defoliate when there is a fairly abrupt change in light levels - from bright to dim, or after exposure to sudden chill, but the plant does not tend to defoliate when the cultural conditions of light and temperature move from unfavorable to favorable, i.e. from dim to bright or from cool to warm/appropriate - unless the change is markedly radical.

Repotting
First, I draw a major distinction between potting-up and repotting. Potting up can be undertaken at any time. It involves moving the plant to a slightly larger pot and back-filling with fresh soil, with a minimal amount of root disturbance. Much to be preferred to potting-up, is repotting. Repotting, which has a substantial rejuvenating effect, includes removing all or almost all of the old (spent) soil and selective root-pruning. It is by far the preferred method and probably the most important step in insuring your trees always grow at as close to their potential genetic vigor as possible. Repotting as opposed to potting-up is the primary reason bonsai trees are able to live in small containers for hundreds of years while the vast majority of trees grown as houseplants are lucky to survive more than 5 years without root work

It is pretty much universally accepted among nurserymen, that you should pot up at or before the time where the condition of the roots/soil mass is such that the roots and soil can be lifted from the container intact. Much testing has been done to show that trees left to languish beyond this point will have growth and vitality permanently affected. Even when planted out, growth and longevity of trees allowed to progress beyond this point is shown to be reduced.

The ideal time to repot a Ficus, is when the plant has good vitality and in the month prior to its most robust growth. June and July are prime months for most of the US. HOW to properly repot is beyond the scope of the initial post, but I am sure the subject will be covered in detail as questions arise.

Remember - potting up a root bound plant is a stopgap fix, and ensures the plant has no opportunity to grow to its genetic potential within the limits of other cultural factors; while fully repotting, which includes a change of soil and root pruning, ensures the plant WILL have the opportunity within the limits of other cultural factors. Strong words, but to repeat the illustration: the bonsai tree is capable of living in a tiny pot, perfectly happy for hundreds of years, while we struggle to squeeze 5 years of good vitality from a root bound plant - root work being the difference.

Pests
Ficus trees suffer from some pests. Most common are scale, followed closely by mites and mealies. I have always had good luck with neem oil as a preventative and fixative. We can discuss infestations and treatment as it arises, but so it gets included in the original post, I use only pure, cold-pressed neem oil, such as that packaged by Dyna-Gro in the black and white container. The beneficial active ingredient in neem is azadirachtin, the effectiveness of which is greatly reduced by steam and alcohol extraction methods, which brings us full circle to why I use the cold-pressed product.

Oedema can sometimes be an issue as well;. Suspect it if you see corky patches on the leaves, usually preceded by wet, bumpy patches that usually go unnoticed.

This is a long post, and took a long time to compose. I hope it answers most of your questions, but somehow, I cannot help but hope there are a few lingering that you would like to ask or points you would like to have clarified. It is great fun visiting and helping people who are devoted about improving their abilities to provide for their trees.

Best luck.

This is how far I was yesterday when I lost the entire post. Imagine how frustrated I was. ;-)

Your soil choice and light source are your 2 most important considerations, which is why I so often urge growers to get the soil right. Fighting your soil for control of your plants' vitality is not a good way to get a satisfactory return for your efforts.

Good luck!

Al




This message was edited Oct 13, 2014 5:52 PM