Potting technique

[jobranch]

My Fragrant Fire is showing some brown edges on a few leaves. I think this is simply a water issue. This is my prized hosta and I water it very regularly. Since we have had so little rain here, I potted this hosta and have it in a shaded area on my front porch along with a few other hostas. This makes it easy for me to care for them during the drought. I think the problem is the pot itself. I am still a beginning gardener and what I think is going on is that this pot does not retain enough of the water I give it. It was potted using premium potting soil from my local home center. I am thinking all I need to do to keep my FF from getting any worse is put some sort of pan like thing under the pot to retain water. If I do this will this overflow of water absorb back into the potting soil and hydrate the plant?

Jeff

[John]

When you check the soil in the container in the soil before watering, is it dry? I'm wondering if the plant might be getting too much water-- or if the water is running through without wetting the soil. My suggestion would be to add about half (by volume) fine pine bark to the potting mix (assuming that it is mostly peat, which holds a lot of water IF it is getting wet-- otherwise it is hard-to-wet). With this improved drainage, you can water as freely as you like, without fear of overwatering. This drainage will be even more important depending on how you plan to overwinter this plant.

And I'd say no to the saucer idea.

[Wild Dog]

Water and Hosta

Water is the answer to dependable hosta horticulture. Remember hosta cannot be over watered unless the crown is under water. With that in mind how does one see that hosta have enough water, water often or manipulate the conditions? Some years ago while attempting to find the outside limits of water for hosta we cut holes in a piece of two inch insulation the size of 8” nursery pots and suspended potted hosta in these holes and floated the hosta in the water feature. They floated in the water for 24/7 365 days a year for three years. They were in full sun and did extremely well during the summer, even on hot days. I left them in the water over the winter to see how they would do. The following spring they came up like weeds and started to grow, not just grow but grow well.

That hosta like wet feet was now a proven theory so we built a bog using pond liner just as one might construct a water feature. These four interconnected ponds were filled with compost, planted, watered and ignored. Our shower was plumbed to this constructed bog being watered every Saturday when I bathe. Again, these hosta are not in the recommended well-drained soil, they stood in water constantly and grew like crazy. The depth is about 12-14 inches with nothing but organic matter, tree trimmings, leaves etc.

Further pursuing this water question a mister was installed to mist plants 24/7. Since misters will reduce the temperature substantially, the plants were located in full sun. I measured the temperature in the mist zone and it was lowered as much as 20 degrees. The plants grew well with constant mist on the leaves and showed little ill effect from the hot full sun location.

This work leads to two conclusions; “hosta cannot be over watered” and hosta are not shade tolerant they are “heat intolerant”. Hosta love the sun and hate the heat.

[Wild Dog]

On page 2 you will find a thread coffee ground.........

Look for the part about how the pot is setup re a constant water reservoir. Let the pot set in about 10-20% water by volume of the pot. It may cause more questions but the main part is hosta can have wet feet 24/7 and address any questions you may have.

If you use this method AND put the pot in a garage over winter without any water during the winter I'll replace your FB if you lose it.

[jobranch]

Bill - So you are in favor of the saucer. With most of my potted hostas, what I have found is that water runs through the pot quickly. I watch this thinking how can this be proper water application?

[Wild Dog]

The water running through is the proper application for a grower with many types of plants with different requirements.

Hosta are specific, duh and they will grow like weeds with wet feet. If you fertilize the pots then reduce the amount by as much 75% or use 1/4 the amount. The fertilizer will collect in the pot then be pulled up by capillary action. If they receive most or all their water from tap or well then they may have salt buildup so leaching 3-4 times a year, if they get regular rain then that should take care of it. Look for the white to brown accumulation at the media surface, if you allow fertilizer salt buildup to get bad then it may require changing media but this is the same with any potting method.

[Wild Dog]

PS, If you make muddy water with local clay and water your potted plants it will increase the cation exchange capacity, a good thing. The muddy water will run through and coat the media increasing the sites for the roots to receive food.

More than you may want to know about CEC.

The cation exchange capacity (CEC) of a soil is a measure of the total number of sites available for ion exchange of positively charged ions, i.e. cations, or the total amount of exchangeable cations. Closely related to cation exchange capacity is the base saturation, which is simply the fraction of exchangeable cations that are base cations (Ca, Mg, K and Na). The higher the amount of exchangeable base cations, the more acidity can be neutralised in the short time perspective. Thus, a site with high cation exchange capacity takes longer time to acidify (as well as to recover from and acidified status) than a site with a low cation exchange capacity (assuming similar base saturations). The long term resistance to acidification, however, is determined by the weathering rate.
There are two standardised ISRIC methods for determining CEC:
· extraction with ammonium acetate; and
· the silver-thiourea method (one-step centrifugal extraction).
There exists slightly conflicting ideas on which mechanisms to include in the term, "cation exchange", in soil chemistry. From a theoretical point of view, one should distinguish cation exchange from ligand exchange, and exchange of diffuse layer adsorbed cations. On the other hand, from a practical point of view, e.g. in forest and agricultural management, what is important is the soils' ability to replace one cation with another rather than the exact mechanism by which this replacement occurs. What is included in the term, "cation exchange", in soil science thus varies with the scientific context.
[edit]
References
· ISRIC (International Soil and Reference Information Centre)
· Robert Lippert, Clemson University Extension Service
· Microsoil.com Cation Exchange Capacity
· David B. Mengel, Department of Agronomy, Purdue University
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Cation exchange capacity
7 August 2002 [reviewed 16 August 2004 ]
Cation exchange capacity (CEC) is a useful indicator of soil fertility because it shows the soil's ability to supply three important plant nutrients: calcium, magnesium and potassium.
Cations
What CEC actually measures is the soil's ability to hold cations by electrical attraction. Cations are positively charged elements, the positive charge indicated by a + sign after the element symbol. The number of + signs indicates the amount of charge the element possesses.
The five most abundant exchangeable cations in the soil are calcium (Ca++ ), magnesium (Mg++), potassium (K+), sodium (Na+) and aluminium (Al+++).
Cations are held by negatively charged particles of clay and humus called colloids. Colloids consist of thin, flat plates, and for their size have a comparatively large surface area. For this reason they are capable of holding enormous quantities of cations. They act as a storehouse of nutrients for plant roots.
As plant roots take up cations, other cations in the soil water replace them on the colloid.
If there is a concentration of one particular cation in the soil water, those cations will force other cations off the colloid and take their place.
The stronger the colloid's negative charge, the greater its capacity to hold and exchange cations, hence the term cation exchange capacity (CEC).
CEC measurement
Concentrations of cations are expressed in centimoles of positive charge per kilogram of soil (cmol(+)/kg). This measurement is equivalent to the previously used unit me/100 g.
Adding the concentrations of each cation gives you an estimate of the CEC figure. A figure above 10 cmol(+)/kg is preferred for plant production. Soils with high levels of swelling clay and organic matter can have a CEC of 30 cmol(+)/kg or more.
[Below]A diagrammatic representation of the flat plate-like structure of a colloid. Its negative charges are along the edges of the plates. The cations are attached to the colloid by electrical attraction between the positive and negative charges.

The five exchangeable cations are also shown in soil test results as percentages of CEC. The desirable ranges for them are: calcium 65–80% of CEC, magnesium 10–15%, potassium 1–5%, sodium 0–1% and aluminium 0%.
pH and CEC
Soil pH is important for CEC because as pH increases (becomes less acid), the number of negative charges on the colloids increase, thereby increasing CEC.
CEC levels
Humus
CEC varies according to the type of soil. Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have large quantities of negative charges. Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility.
Clay
Clay has a great capacity to attract and hold cations because of its chemical structure. However, CEC varies according to the type of clay. It is highest in montmorillonite clay, found in chocolate soils and black puggy alluvials. It is lowest in heavily weathered kaolinite clay, found in krasnozem soils, and slightly higher in the less weathered illite clay. Low CEC values can be improved by adding organic matter.
Sand
Sand has no capacity to exchange cations because it has no electrical charge. This means sandy soils such as podzolic topsoils have very low CEC, but this can be improved by adding organic matter.
Aluminium and sodium
Aluminium (Al+++) and sodium (Na++) cations are not plant nutrients, so are not wanted by the plant. Aluminium is not present as a cation when soil pH (CaCl2) is over 5 because it is precipitated out of the soil solution. It is only at pH (CaCl2) levels below 5 that it may become available as a cation, and under 4.5 may become available in toxic levels, displacing other cations from the clay or humus colloids. This is one reason why it is important to maintain pH levels at 5.0 or more.
When exchangeable sodium is present in quantities greater than about 5% of the CEC, it makes the clay particles unstable in rainwater. This shows up as dispersion or cloudiness in water. Dispersive soils have poor water entry and drainage and set hard on drying.
Average CEC of North Coast soils
Soil CEC (cmol(+)/kg)
Krasnozem
high pH and high organic matter 10–20
low pH and low organic matter 2–6
Chocolate
high pH and high organic matter 30-40
low pH and low organic matter 3-7
Podzolic 3–10
Alluvial
light and sandy 10-20
heavy clay 20-30
Dune sand 0-5
Leaching
If a soil has a low CEC and high sodium levels, up to half the cations in the soil may be in the water around the soil particles, and not actually held by the particles. These cations are very susceptible to being leached or drained away in the soil water.
Soils with a high CEC have a much lower percentage of cations in the soil water, so are far less susceptible to nutrient loss by leaching.
Improving CEC
You can improve CEC in weathered soils by adding lime and raising the pH. Otherwise, adding organic matter is the most effective way of improving the CEC of your soil. This can be done with permanent pasture, regular slashing, green manure crops, leaving crop stubbles to rot, rotating crops or pasture, and the addition of mulch and manure.
From the Soil Sense leaflet 3/93, Agdex 530 produced by Rebecca Lines-Kelly, formerly soils media officer, Wollongbar Agricultural Institute, for CaLM and NSW Agriculture, North Coast region, under the National Landcare Program, September 1993.

The cation exchange capacity (CEC) is a value given on a soil analysis report to indicate its capacity to hold cation nutrients. The CEC, however, is not something that is easily adjusted. It is a value that indicates a condition or possibly a restriction that must be considered when working with that particular soil. Unfortunately CEC is not a packaged product. The two main colloidal particles in the soil are clay and humus and neither are practical to apply in large quantities.The CEC of the soil is determined by the amount of clay and/or humus that is present. These two colloidal substances are essentially the cation warehouse or reservoir of the soil and are very important because they improve the nutrient and water holding capacity of the soil. Sandy soils with very little organic matter (OM) have a low CEC, but heavy clay soils with high levels of OM would have a much greater capacity to hold cations.The disadvantages of a low CEC obviously include the limited availability of mineral nutrients to the plant and the soil’s inefficient ability to hold applied nutrients. Plants can exhaust a fair amount of energy (that might otherwise have been used for growth, flowering, seed production or root development) scrounging the soil for mineral nutrients. Soluble mineral salts (e.g. Potassium sulfate) applied in large doses to soil with a low CEC cannot be held efficiently because the cation warehouse or reservoir is too small.
CATION EXCHANGE

Water also has a strong attraction to colloidal particles. All functions that are dependent on soil moisture are also limited in soils with low CEC. Organisms such as plants and microorganisms that depend upon each other’s biological functions for survival are inhibited by the lack of water. Where there is little water in the soil, there is oftentimes an abundance of air which can limit the accumulation of organic matter (by accelerating decomposition) and further perpetuate the low level of soil colloids.High levels of clay with low levels of OM would have an opposite effect (i.e. a deficiency of air), causing problems associated with anaerobic conditions. The CEC in such a soil may be very high, but the lack of atmosphere in the soil would limit the amount and type of organisms living and/or growing in the area, causing dramatic changes to that immediate environment.If a soil has a very low CEC, adjustments can and should be made but not solely because of the CEC. A soil with a very low CEC has little or no clay or humus content. Its description may be closer to sand and/or gravel than to soil. It cannot hold very much water or cation nutrients and plants cannot grow well. The reason for the necessary adjustment is not for the need of a higher CEC but because the soil needs conditioning. A result of this treatment is higher CEC.


(Reference: Edaphos: Dynamics of a Natural Soil System / Paul D. Sachs - pp 152-153)