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RE: Cherry trees (Follow-Up #22)

posted by: edlo on 02.15.2007 at 09:10 am in California Gardening Forum

Typical means that all the major growers are currently using these rootstocks. GM61 a typical rootstock in the trade that dwarfs to 65% of standard(25 feet +) is the rootstock used for your Ultra Dwarf Cherry. In tests that I have done through the years on container rootstocks I have tested GM61. It performs well for about 4 years then needs to be rootpruned and repotted to keep it going. This prosess sets the fruiting back a season while the tree gets reestablished. I have had better results with the Gisela 5 and would recommend it for home gardeners wanting to do cherrys in containers. The reason Gisela 5 is hard to find is that it has been dissapointing as a commercial rootstock and too expensive for most growers to offer to the public. As far as Krmysk it is too new and has little grower feed back in the states. Though it sounds good now it will be years before growers results recommend it for the home garden. There have been many introductions through the years that have gone no where once they get into production. The industry is not against good results but the industry does not often act on a whim. It is far too expensive. As for Guardian it is in trials and is showing poorly in all but heavy saline/sodic soils(soils with high salts)Texas has been positive on this rootstock I believe. Though a problem in a few areas on the west coast it is not a typical problem and as such expensive for growers to produce just for a few areas.

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clipped on: 01.15.2011 at 03:45 am    last updated on: 01.15.2011 at 03:45 am

How Plant Growth is Limited (container forum version)

posted by: tapla on 09.19.2010 at 09:07 pm in Container Gardening Forum

Photobucket

In a recent post, I suffered criticism after I tried to explain why light could not make up for or 'trump' the negative affects of other factors that potentially limit plant growth. Liebig's Law of the Minimum is a universally accepted concept that defines how the growth of plants is limited. Originally the law was viewed by Justus Von Liebig, a German chemist who is often referred to as 'the father of the fertilizer industry', as a fitting way to define the fact that plant growth is not limited by the total of the available resources, but rather, by the single resource in shortest supply.

Though Liebig's focus at the time was on nutrition, his concept was later expanded to include other limiting factors as they were discovered. Not only are each of the elements commonly regarded as essential to plant growth recognized as having the potential to individually limit growth, but the law has also been expanded to recognize the limiting effects of cultural conditions like light, temperature, levels of soil moisture and aeration, insects, disease, and others.

Liebig used a barrel with staves of varied heights, like you see in the picture, to illustrate how his concept worked. Imagine the barrel also had a stave for light, soil moisture/aeration, temperature ..... for each and every potential limiting factor, insects and diseases included. The picture above is illustrating that in this case, N is the limiting factor. The plant is not growing as well as it could be because it is N deficient. When we add more N, and N is no longer the nutrient or potentially limiting factor in shortest supply, something else takes its place as the limiting factor. Even if the supply of N was increased to the point where it was in perfect supply, the least available nutrient or cultural condition would STILL be the limiting factor. We raise the stave representing N, but then another stave representing another resource becomes limiting.

You can see that if light levels are made perfect, it wouldn't compensate for the effects of a N deficiency or a soggy soil. If it could, we would be able to grow our plants in peat porridge with no supplemental fertilization at 32* F in a wind tunnel .... as long as it was a bright wind tunnel .... or we focused on perfecting light levels. The same is true of soils. The most perfect soil we are able to build will not make up for or 'trump' the effects of a nutritional deficiency or poor light.

Our goal then, is to try our best to make sure ALL the cultural conditions are optimum - making ALL the staves taller, as it were. It doesn't do us any good to make all but one stave taller, because it is that pesky short stave that is going to limit growth - EVERY SINGLE TIME! Surprisingly, it is not as difficult as it sounds.

Light and temperature are actually very easy. The onus of learning your plants' preferences for these cultural conditions is on you, but they are very easy to learn and easy to correct, so that issue needs no more attention. Insects and diseases might be a little tougher, but IPM practices are derived from common sense. Identify the pest/disease and use the least noxious remedy possible to reduce the problem to something below your tolerance threshold.

Modern fertilizers make it easy to supply nutrients at near optimum levels and in a ratio to each other that is favorable. Tucked into Liebig's Law is the fact that too much is as bad as not enough, so there is incentive for us not to cater to the idea that because a little is good, more is better. As we look at the barrel example, we can see that increasing the N supply so the N stave is taller than the P or K staves is not going to help. So, using fertilizers with a favorable ratio and applying them wisely is actually something we can all manage.

Because this is the Container Gardening Forum, the most frequent source of trouble and the issues that arise with the most frequency are soil related. Soil moisture and aeration are staves as critical as any other in the barrel. Just as a perfect soil cannot 'trump' the effects of other short staves, optimizing other conditions cannot offset or 'trump' the effects of a poor soil. The necessity of making sure your plants are adequately supplied with water is an obvious given. The effects of excessive water retention and inadequate aeration are widely discussed on the forum. You can learn how to avoid these issues entirely or almost entirely by reading about How Water Behaves in Container Media by clicking this highlighted text; or you can read some tips about
How to Deal With Water-retentive Soils by clicking on this highlighted text.

Keep learning. The more you know about how your plants grow, what cultural conditions they prefer, and the effects varying cultural conditions will have on your plants, the better equipped you are to deal with them, keeping all the staves tall and minimizing limiting effects.

Al

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clipped on: 09.24.2010 at 03:25 pm    last updated on: 09.24.2010 at 03:25 pm

RE: A Soil Discussion (Follow-Up #88)

posted by: tapla on 12.04.2007 at 11:47 pm in House Plants Forum

You are talking about two different things. First, I'll talk a little about wettability. Generally, soils with high organic content exhibit hydrophobic tendencies (they get difficult to rewet and repel water) when their moisture content drops below about 30%. This is the result of (primarily) iron and magnesium-containing molecules bonding to soil particulate surfaces after exposure to O2 and H2O, making it more difficult for the water molecules to be adsorbed to particle surfaces and to be absorbed into the organic particle proper. (it won't soak in or stick to the peat and bark) Once sufficient wetting has occurred to allow the metal molecules to go back into solution, the particles become more easily wettable again.

To see how I compensate for this physical condition - from another thread:
"There IS a way to water that is is most effective - that allows you to maintain a favorable level of nutrients, while still allowing you to flush accumulating salts from fertilizers and irrigation water from the soil. Not all of us can adopt this method because it is time consuming, but if you have only a few plants (or don't mind doting on the ones you have), ;o) you might consider:
Slowly & evenly apply water to the soil surface until the soil is almost saturated, but no water appears yet at the drain hole (after a time or two, you'll learn approximately how much water you should use to achieve this initial level of saturation). Wait 5-10 minutes for accumulated salts to dissolve into the water you just applied. Water again, so that approximately 10-15% of the total amount of water applied in both waterings exits the drain hole. This flushes a large % of accumulated salts from the container."
This allows the offending molecules to go into suspension & makes the soil easily wettable, so the soil is thoroughly wetted on the second watering and offending accumulating metal salts are flushed from soils.

I should also mention that there are certain microorganisms that also can affect wettability, but they usually show up on the very top surface as a noticeable crust.

The reason the water that collects in the saucer is drawn back up into the container is because the soil was not fully wetted to begin with. If it was, no additional soil could be ab/adsorbed. Also note that even if no water is drawn into the container from the saucer, the dissolved solids in the saucer, through the natural tendency to osmotically balance, will STILL migrate into the container soil solution until the level of dissolved solids is the same in the soil solution as it is in the saucer. So - it is very important to see that the drain water cannot be reabsorbed into the container.

The PWT (the level of saturated soil that occurs at the bottom of containers, but can/does occur above drainage layers as well): For our purposes, we can practically say that the PWT is a function of particulate size and uniformity in an inverse relationship. The smaller and less uniform the soil particle size - the taller/higher the PWT, until as uniform particulate size approaches 1/8", the PWT disappears entirely. FWIW - for any drainage layer to be effective at draining water from containers, the particle size in the drainage layer must be no larger than 2.1x the size of the particles in your soil.

Did that answer your questions?

Any others reading: Just because the conversation has turned temporarily technical is no reason not to ask whatever soil questions you might have. ;o)

Al

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clipped on: 09.18.2010 at 01:33 am    last updated on: 09.18.2010 at 01:33 am

RE: Granite+turface mixtures (Follow-Up #1)

posted by: tapla on 08.15.2010 at 09:00 pm in Container Gardening Forum

Roots don't really push through the medium - they grow around the soil particles & then expand.

Use gypsum as the Ca source, as pH of the Turface/granite mix will be slightly higher than that of the same mix w/bark included.

I grow lots of plants with a very small or no organic fraction, so the screened Turface/granite mix is fine. If you're noticing slow growth, it's probably because you're not providing enough nutrition (not fertilizing often enough or at a high enough concentration), or there's a hole in your supplementation program (an element missing that's inhibiting growth).

A copy/paste from something I wrote earlier: Liebig's Law - Certainly some of you have come across this before. First, there are 6 factors that affect plant growth and yield; they are: air water light temperature soil or media nutrients. Liebig's Law of Limiting Factors states the most deficient factor limits plant growth and increasing the supply of non-limiting factors will not increase plant growth. Only by increasing most deficient factor will the plant growth increase. There is also an optimum combination of the factors and increasing them, individually or in various combinations, can lead to toxicity issues/reduced growth.

Al

NOTES:

Liebig's Law of Limiting Factors states the most deficient factor limits plant growth and increasing the supply of non-limiting factors will not increase plant growth
clipped on: 08.21.2010 at 03:29 am    last updated on: 08.21.2010 at 03:30 am

RE: when can you stop repotting (Follow-Up #6)

posted by: tapla on 07.08.2010 at 02:16 pm in Citrus Forum

IMO, it's not wise to ignore what we know about the way trees grow in containers in favor of anecdote, especially since 'how well' any particular tree is doing is a very subjective thing.

We know for certain that growth is negatively affected at about the time the soil/root mass can be lifted from the container intact. We also know that once the tree has reached this state of root congestion, growth is affected permanently, unless the root congestion is corrected. We know these things because tree growers have a vested interest in seeing that their trees put on caliper as quickly as possible. Dr Carl Whitcomb goes into some considerable detail about what the impact of being root bound has on growth. Practically speaking, after spending thousands of hours digging around in as many root balls, I can assure you his observations are accurate.

You cannot expect a tree growing under root-bound conditions to grow to its genetic potential within the limits of other cultural factor, and it will not/cannot. When you regularly tend to root pruning and and replacement of collapsed soils, you offer your tree the opportunity to grow at as close to it's genetic potential as other cultural factors allow, but when you simply put a tree in a container & do nothing in the way of root maintenance, you deny that plant that same potential.

On a scale of 0-10, with 0 being a dead tree and 10 being perfect vitality/growth, trees in containers are capable of somewhere around an 8. A scenario re the range of vitality: Trees that are repotted (includes soil change and root work) will vary over a 3 year period (between repots) and at some point soon after repotting will be capable of growing at a level of 8. They will decline to maybe a 5 as they become root bound. When you repot, they go right back to 8 again, so the trees can be maintained indefinitely at good vitality levels.

Let's consider the tree that is NOT repotted. Some may feel that because they see a growth "spurt" after they pot up or scratch some fresh soil into the top few inches that all is well, but lets talk about that growth "spurt" It's not a spurt at all. It's simply a very stressed tree temporarily growing a little closer to it's potential, which has been misinterpreted as a spurt.

*A tree starts at a vitality level of 8 and declines to a 5 over 3 years.
* It's potted up and some of the vitality returns, but not all, so it's only growing at a level of 7.
*Over 3 years, it declines to a 4; when potted up again, it can only muster a vitality level of 6.
* It declines to a 3 and is potted up to a 5
* It declines to a 2, and is potted up to a 4
* It declines to a 1, and is potted up to a 3

By this time, the stress has turned to strain, any the trees natural vigor can no longer sustain it against insects & disease, so the tree succumbs to an inability to make more energy than it uses because it cannot grow. A tree that is not growing is dying. Dr. Alex Shigo.

I generally reject anecdotal testimony about trees in containers that are growing with good vitality after X number of years that have only been potted up because I know it's impossible. Returning full circle now to what I said in the opening paragraph: people can SAY this because "good vitality" is a very subjective thing. I would simply point to the fact that you virtually never see old, robust containerized trees unless someone IS tending to the roots, which is why most containerized trees are in such frequent need of replacing while bonsai and their tended roots are passed down through hundreds of years, even in spite of the difficulties presented by their minuscule pots and soil volumes.

Al

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clipped on: 07.09.2010 at 04:05 am    last updated on: 07.09.2010 at 04:05 am

RE: Drainage for beds in clay soil (Follow-Up #14)

posted by: tapla on 03.30.2009 at 10:19 pm in Square Foot Gardening Forum

Let's say you're starting with a raised bed (RB) with a highly organic RB soil on top of any type of undisturbed soil. Eventually, the texture of the soil below the raised bed will be changed. When the native soil is one that allows percolation or adequate drainage, there is no problem, but in clay soils, there is. Eventually, there will be greater porosity in the clay immediately under the beds to fill with water when it rains or when you irrigate. Even if the argument is made that this will take place over an extended period, we can still make the statement that disturbing the soil under the beds, and especially disturbing AND amending with organic matter IS going to create the bathtub effect.

You are better off, on clay soils, to build the bed on top of undisturbed earth. As water accumulates in the RB soil, it pushes down on the water in the soil at the bottom of the bed. If this water is impeded by the extremely slow percolation rate through the clay, it will flow laterally across the top of the clay as long as rain or irrigation continues; or it will move laterally by diffusion through the very top layer of soil. In both cases, because the surface area whetted by the water from the raised bed is very large, evaporation will occur and the capillary pull of the clay surface will continue to pull water from the beds.

To visualize this: Saturate a sponge (the sponge is your RB soil) - hold it so the largest surfaces are horizontal until it stops draining. Set it on a counter top (the near-impermeable clay layer). Note that no water flows away from the sponge. Now pour a Dixie cup of water on the sponge (this is rain or irrigation). See how water flows laterally across the counter top?

Do it again - hold the sponge horizontally until it no longer drains. This time, set it in the center of a dry paper towel (the top of the native clay soil). Note how the water flows laterally across the paper towel? If the paper towel was larger (like the huge area of soil surrounding the beds) it would pull all perched water from the sponge. Since the towel greatly increases the surface area that is wet, evaporation can occur at many, many times the rate it would w/o the towel (the surface of the native soil).

Turn your thoughts to amended soil under the bed. The water from the bed and surrounding undisturbed soil fills the amended bowl and the water has nowhere to go. It is not exposed to the air, so it cannot even evaporate. See where the problems lie?

Al

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clipped on: 06.29.2010 at 12:44 pm    last updated on: 06.29.2010 at 12:46 pm

RE: Drainage for beds in claysoil (Follow-Up #3)

posted by: tapla on 03.13.2009 at 10:25 am in Square Foot Gardening Forum

The gravel won't help because water will just move laterally to fill the pores between the stones. Unless you have somewhere for the water to 'go', you're stuck with the 'bath-tub' effect. If you can insert a tile at the bottom of the depression that will drain downhill, you can remove the water. You could also install a collection crock and pump it out. Filling the disturbed depression with anything but native or finer soil will guarantee this bathtub effect, and even native soil will create the effect because it was disturbed. It would disappear once the soil has resettled & compacted to the same degree as surrounding soil though. (See note about soil biota and the bathtub effect later in the post)

For practical application, you have to consider that the supply of water that can run into the depression is unlimited because of the fact that water will move laterally, even through clay, from surrounding soil, so the volume of the depression, or the depth, in all but a minute number of cases is not a factor. You should consider that 'when it rains. it's going to fill.

You'd have been better off had you simply built the RB directly on top of the clay and allowed the downward movement of the water in the RB soil to be arrested by the (near) impermeable clay where it would flow laterally around the RB sides and over the surface of the clay where it would quickly evaporate or flow to a lower point.

Eventually though, soil biota will incorporate the OM from the RB soil into the clay substrata & (passively?) create the same bath-tub effect as the double-digging.

Al

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clipped on: 06.29.2010 at 12:33 pm    last updated on: 06.29.2010 at 12:33 pm

posted by: (Guest) on in Forum

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RE: blueberry container soil and fertilizer (Follow-Up #6)

posted by: justaguy2 on 03.25.2008 at 06:28 pm in Container Gardening Forum

Filix,

I no longer grow blueberries in containers, but used to. I now grow them in the ground exclusively as I find it easier (no need to protect for overwintering), but the idea behind high yielding blueberries is the same.

In nature we don't find blueberry shrubs all that often. They are a niche plant. Most commonly we find them in low lying areas where water runs off to (keeping the ground moist) and also where organic matter settles to (ensuring the soil in high in organic matter). This has resulted in a rather unusual biological adaptation that makes blueberries a niche plant rather than a common one in nature.

Blueberries are shallow rooted and produce few to no feeder roots. This is really important to grasp in my opinion. The fine, hair like roots most plants produce are feeder roots and take up most of the water and nutrients the plant gets. Blueberries simply don't produce these. This means they are very inefficient at water/nutrient uptake.

In nature this is OK because blueberries thrive in highly organic and fairly evenly moist soils. It isn't necessary for them to be efficient at water and nutrient uptake as they have a nearly constant and plentiful supply of both.

In nature the highly organic soil means that various fungi also thrive and one critical to the success of wild blueberries is mychorrizal fungi. This is a specialized fungi that forms a symbiotic relationship with certain plants. The fungi forms long, thin strands that perform the function of feeder roots. They extend deep and wide in the soil and take up water and nutrients. In exchange for feeding the plant, the plant exudes substances from the roots that feed the fungi.

In a container pretty much none of this occurs. Trying to replicate nature in a container is futile as highly organic soils will just compact too much and trying to establish mychorrizal fungi is impossible without steady environmental conditions which cannot be had in a container situation.

One other consideration for blueberries is that in nature these low lying areas also sport fairly cool soils. Much cooler than the soil at higher elevations. This is perhaps the most challenging part of blueberries in containers, particularly for those in hot, arid climates. More recent cultivars do improve the heat tolerance of some blueberries though.

To grow real quality blueberries in containers is not difficult once one understands that in nature blueberries get cool soils, nutrient rich soils and moist soils.

I almost forgot to mention that the soils wild blueberries thrive in are highly acidic. More acidic than any other plant you are likely to want to grow. This is another important consideration for container growing although again, more recent cultivars reduce the necessity for strongly acidic soils.

What is the best potting mix for container blueberries? There isn't one ;-) What is the ideal pH of the mix? It really doesn't matter (within reason).

In a container we need a mix that retains water long enough that we can keep it moist. Keeping the mix moist is very important for good health and yield. If you try a mix and find it goes dry before you can water it again then it isn't a good mix for you.

We need a mix that retains nutrients well enough that the shrub doesn't lack anything between fertilizing. This is much less an issue than water retention since watering and fertilizing can be done together.

We need an acidic growing medium. In a container this can be accomplished by either using a fert for acid loving plants or using household vinegar to acidify the water. In most cases we won't add fertilizer with every watering so the vinegar goes a long way to ensuring the pH is acceptable to the shrubs. How much to use varies depending on the water source, but a general rule of thumb is 1/2 cup vinegar (ordinary, white distilled from the grocery) per gallon of water. Often this much isn't necessary, but won't be excessive with tap/well water due to it's buffering capacity.

What I consider critical to container blueberries is understand the pH of the planting mix is far less important than the pH of the irrigation water. Plants do not take up nutrients from the soil or planting mix. They take up nutrients from the water in the soil/planting mix. For this reason to get nutrients to the shrub in the right ratio isn't dependent upon the soil/mix, but the water. If the pH of the water is out of whack the plants suffer.

Good container blueberries can be had with a good planting mix (such as Al's mix), keeping them moist and as cool as one can (shade the containers in hot climates) and adding an acidic fertilizer (like Miracid) to the water or adding vinegar to the water when not fertilizing.

Overwintering is a bit more difficult in containers due to little insulation value in containers which is why I don't container grow them any longer, but is certainly doable if you take the trouble to protect them.

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EXCELLENT!
clipped on: 01.31.2010 at 11:07 pm    last updated on: 01.31.2010 at 11:07 pm

Soil substrate comparisons

posted by: xerophyte_nyc on 12.05.2007 at 07:54 pm in Cacti & Succulents Forum

First of all, I seem to have a little too much time on my hands! You'll see what I mean.

I decided to conduct a simple yet instructive experiment. I wanted to compare porosity and water retention of various substrates: Perlite, Turface MVP, coarse gravel, lava rock, peat based mix, garden soil, and 50-50 gravel and soil.

I used 3 equal volume plastic cups. One was calibrated with % values and filled with water. The other 2 were filled with substrate, and 1 of those had drainage holes.

The first thing done was to fill the non-draining cup with substrate to capacity with water. The remaining water is determined as a %. This tells us what % by volume is air, and so is a measure of substrate "porosity".

Second, the draining cup with substrate was also filled with water - whatever drained out was also collected and measured. This tells us how much water was retained by the substrate, "water capacity".

Finally, a ratio of "water capacity" to "porosity" was created, I call it the "saturation index". An index value of 100 means all available air space is filled with water when the substrate is saturated.

Let's look at the photos, they will help to make sense of it:

The column on the left shows the substrate filled to capacity with water, the adjacent cup shows how much water is left in the cup as a %.

The column on the right shows the substrate with a drainage hole, so the adjacent cup displays how much water was drained out, as a %.

Here is the data in table format:

Some discussion on the materials:
The "peat" is a bagged mix that consists mainly of slightly moistened peat with some composted bark. The other substrates were dry. The "soil" is from my garden, probably minimal organic component, on the clayey side, but otherwise more or less a typical loamy soil.

The lava rock is probably very similar to if not the same as pumice, only what I have is pretty coarse. Perlite is horticultural grade. Turface is a high-fired clay product. Coarse gravel is from the pet store. 50-50 is equal parts of the gravel and garden soil.

Observations
As expected, perlite, turface and lava rock have the most air space per volume. I was surprised though that the peat was almost as porous. This must be why it is marketed as a soil aerator, but it decomposes over time, unlike the other drainage materials. The gravel is slightly less porous because it is fine sized. Soil is the densest.

Another surprise, the turface retained more water than the peat mix! Peat and soil had the next highest water capacity. Gravel, perlite and lava rock had the least capacity for water retention, not surprising.

Saturation Index: soil is the worst...this means that when saturated with water, there is hardly any available air in the substrate. The 50-50 mix is 2nd worst. Turface also is pretty high, but considering it is so porous, there is still good aeration. Perlite, gravel and lava rock not surprisingly have the best ability to remain aerated.

Conclusions
I can't make any profound statements here because there are so many interactive factors when mixing these things in a pot that my head would explode if I even tried. Example, perlite is very porous but mixed with something like fine sand or soil, these spaces are then filled so you lose some of this effect. Although if you look at the 50-50 data, it is pretty much a straight average between the 2 separate parts.

Too much perlite, coarse gravel, or lava rock (pumice) reduces the ability of the mix to hold onto moisture so the mix would dry out quickly. Turface, however, is just as porous but simultaneously holds enough water to keep the mix from becoming too dry. Peat has decent properties but they don't last. Soil by itself is terrible, but mixed with perlite, lava rock or gravel would seem to provide similar results to using turface alone. Turface + soil may retain too much water.

A mix that contains somewhat equal amounts of A) turface, B) perlite, gravel or lava rock and C) loam or equivalent would seem to have good overall porosity, aeration, and some water holding capacity.

x

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clipped on: 01.27.2010 at 01:13 pm    last updated on: 01.27.2010 at 01:13 pm

RE: Trees in Containers (Follow-Up #64)

posted by: tapla on 10.12.2008 at 01:20 pm in Container Gardening Forum

"In other words, once I have root-pruned, do I need to worry about pruning the actual tree? ... or do I decrease need for more roots by pruning the tree?"

Good question ... and there are many considerations to take into account that make it kind of difficult to give a 'one size fits all' answer. You DO decrease the volume of roots necessary to support the canopy when you prune the canopy, but roots are (energy) storage organs & will give up stored photosynthate (sugars and starches - basically their store of energy) to help the tree produce more leaves after you prune. If there is not enough energy returning from the canopy to support the roots after they have given up their store, the tree sheds them. You can see a similar example of the tree drawing energy and nutrients from its parts before it sheds them in the way leaves change color and abscise (fall off) when there are macronutrient deficiencies and to a large degree when deciduous trees shed leaves in Autumn.

Timing also plays a large part in whether a tree grows compact or exhibits lots of extension and increase in o/a mass. Trees pruned in early spring (before bud-break) will be affected only fractionally in biomass increase when compared to trees pruned in early summer after they have spent the energy they have kept stored over winter to produce the foliage you remove.

The tree will always try to balance the ratio of roots to foliage. If you prune the canopy hard, the roots will give up their store of energy and then die back to whatever volume is required to support the canopy. If you prune roots hard in spring, the tree is likely to activate only the buds roots can support. If you prune the roots to the degree they cannot support the canopy at any other time, the tree will likely shed leaves & branches until the ratio of canopy:roots is again in balance. That is why we 'baby' certain root pruned trees by siting them in shade and taking steps to minimize transpirational loss after the operation.

There are other factors that come into play, but those are some of the most basic considerations that would affect your decisions.

"Also I need a "guide"(with pictures) of all the different types of roots you all mention: buttress roots, perennial roots, fine rootage, etc. Where can I find this?"

You can search root biology, root metabolism, or root physiology online & come up with lots of information. Some of Dr. Alex Shigo's works would have all the info you need, but they are expensive and might be a little difficult to understand if you lack a good basic understanding of plant physiology. Growth control in Woody Plants and Physiology of Woody Plants by Kozlowski/Pallardy are, again, both great texts, but are expensive and tough sledding for most hobby growers. If you're serious about learning, you can find LOTS of good info on the net, and get many of your specific questions answered here.

Buttress roots are the very large roots attached to the tree where it flares out as it enters the ground. Perennial roots is a term that describes roots that survive from year to year - roots that the conditions of winter do not kill. I often use that term to illustrate there are degrees of hardiness in roots and generally, the more woody the roots are, the more hardy for that tree. Fine rootage is the smallest of the roots - they are the little hair roots largely responsible for uptake of nutrients and water. They are in constant flux - dying when conditions are unfavorable & regenerating when they return to favorable again, making it advantageous for us to learn what conditions are favorable & how to keep them that way. ;o)

"I have a 6'tall sweetgum I want to keep in a container and also some evergreens: cassia bicuspularis and a Hibiscus tiliaceus var tricolor. I want them to provide shade of our patio more than anything."

There should be no problem keeping them in containers. I would suggest you use white pots, or utilize a cache pot so you can keep the roots cooler in summer to minimize heat stress, though. Another important consideration: When the trees get tall enough to provide the shade you seek, they will be very susceptible to being toppled by the wind, so it would be a good idea to address that issue in your thinking as your plan progresses.

Good luck, Teeka. ;o)

Al

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clipped on: 01.17.2010 at 06:23 am    last updated on: 01.17.2010 at 06:23 am