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RE: Trees in Containers III (Follow-Up #91)

posted by: tapla on 05.03.2012 at 10:16 pm in Container Gardening Forum

It's soo hard to be specific when looking at a 2D picture. I know I could prune it in under 10 minutes to give you a framework to build on, but that requires being able to look at the tree from all sides so you can take in ALL the spacial considerations for both the present AND the future.

First, you can hardly go wrong on a young tree, no matter what you do, because you can always fix it. You could chop that tree off immediately above the tiny little first branch on the trunk, and in a few years, you wouldn't even know you did it.

Here is what I would do. Look over the tree and wherever 3 or more branches emerge from the same point or very near the same point, reduce the number of branches to 2 - to a 'Y'. Think about it and keep the branches that contribute most to the composition. If you can't decide, keep the thinnest. Then, post pictures from different angles and we'll look at it with an eye to shortening it.

If you want it to remain in a pot, you should probably get used to the idea you're going to be continually cutting it back. You'll LOVE those tools (pics above) if you don't mind being separated from a few bucks .... or can convince someone they would make a perfect gift.



pruning advice
clipped on: 04.16.2013 at 08:19 am    last updated on: 04.16.2013 at 08:19 am

RE: Container Soils - Water Movement & Retention XIII (Follow-Up #67)

posted by: tapla on 04.04.2011 at 06:18 pm in Container Gardening Forum

Perlite BB-size to about aspirin or a little larger is good.

I screen my peat into a rectangular mason's tub in a wheelbarrow through 1/2" screen to break up all the clumps & separate the big sticks, then I pour it into a 5 gallon bucket as a measure. It's dry & fully lofted when I measure.

You CAN reuse the 5:1:1 mix if you wish, but ALL soils deteriorate at an accelerated pace as they age. For clarity, bark based soils break down at about 1/5-1/4 the rate of peat based soils on a particle size to particle size basis, but just because a soil breaks down at a rate slower than peat isn't reason enough to press it into service beyond it's ideal life.

I'm pretty comfortable leaving plants in the 5:1:1 for 2 years. If I had to reuse, I would add maybe 3 parts of bark to 1 part of old soil, along with 1/2-1 part of perlite and a little lime.



Re-using the 511 mix if nec.
clipped on: 04.15.2013 at 04:55 pm    last updated on: 04.15.2013 at 04:56 pm

RE: Container Soils - Water Movement & Retention XIII (Follow-Up #16)

posted by: tapla on 03.22.2011 at 06:36 pm in Container Gardening Forum

Oh hey - THANKS, Jenn! What a great testimony to your stick-to-itivness! I'm really glad you hung in there! The compliment was nice, but I think I'm more pleased with your success!! Of course, you have a free lifetime pass for any questions I can answer. ;o)

The short version of gypsum vs lime: Lime does two things - it lowers pH and supplies both Ca and Mg. The 5:1:1 mix comes in at a lower pH than the gritty mix, so lime does what it does in that soil - raises pH, supplies Ca/Mg.

The gritty mix comes in at a little higher pH, so to keep the soil in the ideal range, we use gypsum (it DOESN'T raise pH) to supply Ca (and sulfur). When you add Ca to a soil w/o adding Mg, an imbalance in the Ca:Mg ratio can occur, and the result can be an 'antagonistic' deficiency of Mg. To combat that, when you add gypsum, you need to include some Epsom salts (also does not impact pH) in your fertilizer regimen to keep that Ca:Mg ratio at a favorable level.

Except: when you use Foliage-Pro fertilizer (it supplies both Ca and Mg in a favorable ratio - unusual where soluble fertilizers are concerned) with the gritty mix, you can skip both the gypsum AND Epsom salts.

Too much N can affect the pollen of some plants - tomatoes and peppers included, making it sticky & unwilling to fly around & do its thing. That, though, isn't a function of the fertilizer ratio - it's a function of how much N you actually apply. Properly applied, 3:1:2 ratio fertilizers are no more likely to inhibit pollination than 1:1:1 ratios. The ratio doesn't determine the dose - you do. ;o)

Thanks again!



difference between gypsum and lime
clipped on: 04.15.2013 at 04:48 pm    last updated on: 04.15.2013 at 04:49 pm

RE: Is it OK to reuse the run-off water? (Follow-Up #2)

posted by: rina_ on 03.26.2013 at 12:26 am in Container Gardening Forum


Here is answer to your question - Al (tapla) answering someone else on House Plants forum (thread: Watering issues):

Posted by tapla z5b-6a mid-MI (My Page) on Fri, Mar 22, 13 at 9:53

One of the most significant benefits of using soils that allow you to water copiously with no concern about potential root problems related to excessive sogginess is the fact that the ability to flush the soil at each watering prevents dissolved solids (salts) from building up in the soil. Ideally, when you water you would allow the effluent passing out of the drain hole to run down a drain or collect in a saucer. When it DOES collect in the saucer, the container should be lifted above the effluent, so after it exits the pot, there is no way the dissolved solids contained in the effluent have any chance of getting back into the soil. I set my pots up on little 1-1/4" blocks that rest in the saucer. I don't need to empty the collection saucer because the water that collects there can't get back into the pot. It evaporates and contributes to the area humidity, but you could empty the collection saucer if you like, or water over the sink.
The higher the level of dissolved solids in the soil solution, the more difficult it is for the plant to take up water. So a soggy soil that impairs water uptake combined with a high level of salts in the soil solution is a double whammy for a large fraction of growers who use heavy soils that don't allow them to water so they're flushing the soil. This problem is always most prevalent in the spring, after a long winter of watering in sips, or in your case, of pouring residual salts back through the soil, which ensures a gradual but continual increase in the level of dissolved solids that affect water uptake AND nutrient uptake.

If you're using a fertilizer that might not be a problem if you're watering properly, it can quickly become a serious problem if you're NOT watering properly. We know the impact of dissolved solids on the uptake of water also limits the ability to take up nutrients, but when dissolved solids accumulate the ratio of nutrients to each other in the soil can quickly become skewed, which has the effect of one nutrient present in excess making it difficult or impossible for the plant to take up another nutrient. This is very common when using fertilizers with too much phosphorous, and is quickly exacerbated when the soil isn't flushed regularly.


Posted by tapla z5b-6a mid-MI (My Page) on Fri, Mar 22, 13 at 15:57

If you're using the gritty mix, there is very little possibility that you're over-watering, or that flushing the soil thoroughly would create a problem, so I would do that. If you didn't screen the mix carefully, and there are fines in the soil, then use a wick and tilt the pot after you flush - then water normally. I use a level 1/4 tsp/gal of FP 9-3-6 every time I water, and I've been well pleased with the results ever since I settled on that amount, so I'm thinking you could cut back on the amount of fertilizer you're providing. I'm pretty sure that with the 1/2 tsp/gal + the recycling of the effluent, that your plants are seeing some fertilizer burn.
There are some advantages to fertilizing every time you water, and at 1/4 tsp/gal, you get about 800 gallons of fertilizer from a quart of fertilizer. @ $25/qt for the fertilizer, a gallon of solution costs about 3 cents per gallon. Most people would hardly think twice about buying and paying for the electricity augment light levels for their plants - and that's a much more significant outlay than the small amount of fertilizer that might get discarded after passing through the soil. If you want to, collect the effluent in a bucket & spread it on the lawn or your garden/beds.

Plants that are fertilized at higher rates (luxury levels) often show symptoms of deficiencies when the concentration of nutrients in the soil returns to the adequacy range, so that's one + of fertigating @ each watering (it won't happen). Another is, even in nature, nutrient uptake is very closely linked (almost directly) to water uptake, the primary modifier being temperature, which isn't a particularly significant factor when houseplants are the topic. I said that so I can say there is some benefit in not having to keep track of what needs fertilizing when. I fertilize and water everything at nearly the same intervals, and at the same fertilizer rates, and for the last 15 years or so, my plants have all been practically free of blemished foliage. You're trying to do essentially what I (and many others) have been doing, so I expect that once you get the bugs worked out & get your dosages refined, you'll begin to see how easy it can be. I'm pulling for you! ;-)


clipped on: 04.07.2013 at 12:59 pm    last updated on: 04.07.2013 at 12:59 pm

RE: 3/8' screen (Follow-Up #9)

posted by: tapla on 11.27.2010 at 01:34 pm in Container Gardening Forum

It's a difficult question to answer, Nance. Ideally, the particles in the inorganic fraction of the gritty mix would be in the 1/10-1/8" size range, and the bark fraction a little larger, in the 1/8-1/4" size range.

Drainage characteristics are determined primarily by the size of the highest % of particles. To illustrate: if you had a soil that was 2 parts peat, and you added 1 part large bark to it, it wouldn't change drainage characteristics or the ht of the PWT. If you had 1 part peat and added 2 parts large bark to it, it would significantly impact the drainage characteristics.

There is also a stratification issue. If the bark is significantly larger than the other components, the components tend to separate into layers. For my own purposes, I would consider the bark in the first picture to be too large for the gritty mix. Screening the remainder over a household strainer (quite a bit smaller than 1/8") or insect screen is going to leave some particles that are finer than ideal. I think that what does pass through 3/8 mesh but doesn't pass through 1/8" mesh is very good for the gritty mix. IOW, it might be better if you screened over 1/8" instead of the strainer.



clipped on: 04.01.2013 at 09:16 am    last updated on: 04.01.2013 at 09:37 am

RE: Repotting and Pot Size Questions (Follow-Up #7)

posted by: tapla on 09.02.2012 at 11:38 am in House Plants Forum

To expand on the above - Deeper pots are actually easier to grow in, but only if you're using a soil that supports a notable volume of perched water. Soils like MG and MGMC usually support from 3-6+" of perched water at container capacity (when the soil has been fully saturated & has just stopped draining). If for conversational purposes we say that a soil supports 4" of perched water, in a 6" deep container 2/3 of the soil is completely saturated, and in a 4" deep container 100% of the soil will be completely saturated at container capacity. When this saturation occurs, root function can be seriously affected, or worse, root rot can get a foothold very easily. In a 12" deep container, the same soil would only have 1/3 of the soil volume saturated at container capacity, which is why it's easier to grow in deeper containers.

When using soils that support little or no perched water, it doesn't matter how deep the container is or how large the volume of soil. You can't over-pot because it's only the volume of perched water a water-retentive soil contains that makes over-potting such a bugaboo.

That isn't to say that simply growing in a deep container cures all soil ills. There are still the issues of reduced O2 volumes in soils that support significant amounts of perched water, and the noxious gases (sulfurous compounds, methane, CO2 ....) that are produced in the anaerobic conditions that prevail at the pot bottom to consider when using water-retentive soils.

There are 2 perspectives to look at when we say some plants like to be root bound. One perspective is the grower's, and it's more accurate to say I like to grow this plant root bound, because .....
* It keeps the plant smaller, and that's what I prefer
* It helps me deal with my water-retentive soil and allows air to return to the soil faster
* I tend to over-water, and it helps reduce the negative impact of that practice because tight roots allow air to return to the soil faster
* I think it helps increase bloom profusion in this particular plant

None of the above are from the plant's perspective. The plant simply recognizes tight roots as stress, and stress is something the plant would prefer to avoid. Stress can lead to strain, and strain if uncorrected always leads to death of the organism. Stress means the plant is operating at near the limits it was genetically programmed to deal with, and strain is the plant operating at beyond those limits - neither is a good thing from the plant's perspective, so no plant prefers to be grown with tight roots, no matter how well they seem to tolerate that condition.

Often, plants with extremely tight roots are dying, albeit slowly, we just fail to recognize the symptoms of their decline for what they are. Most of us here at GW have come to recognize the difference between potting up and repotting, but the hobby container gardening community apart from the few that we forum denizens represent, for the most part haven't a clue about how much benefit can be extracted from a simple root-pruning and repot as opposed to potting up - the difference is very significant.


Here is a link that might be useful: More about tight roots


clipped on: 04.01.2013 at 08:39 am    last updated on: 04.01.2013 at 08:39 am

RE: Foliage Pro & Pro Tekt (..AL..) (Follow-Up #12)

posted by: tapla on 11.24.2012 at 01:27 pm in House Plants Forum

Lol - up in the middle of the night fretting over fertilizers? Please tell me something else had you up at that hour. ;-)

Here's how I fertilize in the winter: I water/fertilize (fertigate) every time I water with a low dose of fertilizer. Not everyone CAN fertigate that way - it depends on your soil choice and watering habits, so don't emulate unless you understand the ramifications. After I'm done fertigating, I fill 5 - 1 gallon milk jugs with tap water and add just under 1/4 tsp of 9-3-6 to each, and let them rest for the 4 day interval between fertigating, so they come to room temperature. I've asked a LOT of degreed hort people if plants suffer adversity from being watered with cold water, and not one has ever offered anything conclusive that says it's either good or bad, other than potential damage to foliage on some plants, like AVs. Most bonsai books suggest that a cool drink during the midday time period is very helpful because it quickly cools roots down, so apparently the 'shock' thing is a perpetuated myth. Still, it's no extra effort to allow the water to come to room temp, so that's what I do.

When I fertigate, I use a watering can with a long spout that allows me to reach plants in the center of my 4x8 growing areas. The spout has a fine nozzle that sends out a 1/8" stream of water, so it take on average about 20-30 seconds to water a plant. This allows me to wet the entire surface of the plant, so gravity moves the solution down through the entire soil mass. When I see water flowing into the collection saucer, I water for a few more seconds, then stop. My plants are set on pieces of plastic u-channel above the effluent, so I don't need to empty the saucers. The evaporating water means my humidifiers run less.

When it's time to water, I pour 2 qts of fertigation solution from the gallon jug into the watering can. I then add 3 drops of ProTeKt while the water is still turbulent, so it mixes well. I don't mix it in until the last minute because mixing the fertilizer and ProTeKt ahead of time causes some of the elements to precipitate from (fall out of) the solution.

You asked if the ProTeKt is necessary. I think it's good to remember that in many cases, we approach growing with only our own perspective in mind. Much disagreement arises between someone who thinks their way is good enough for everyone because they are happy with it, and the grower who has found a way superior to that particular way and wants to share it. People very often get defensive when someone suggests that what someone says or does isn't the best way. "Well, it works for me!" really isn't very conclusive when it comes to deciding what might or might not be best for the plant. In addition to that, some growers place a high premium on 'less maintenance is better (for me)', while the next grower is trying to make the point that MORE maintenance is better (for the plant).

I tend to always speak from the perspective of how to get to what's best for the plant, and then let the grower decide if they want to go to any extra effort or expense that might be entailed in getting there.

So, the ProTeKt isn't necessary if your goal is to raise a healthy plant. I had healthy plants for many years before I started using it, but after I started using it, I noticed a lower incidence of insect and disease issues, and I noticed that my plants seemed more resistant to temperature extremes. I noticed these things even before I read a few of the many studies that quantify the effects of aqueous Si on plants, so if I was dreaming, I was at least dreaming in accord with the conclusions of others who made the actual effort to nail down the Si's effects on plants. I can't really tell you it's necessary, but I can say with a fair degree of certainty that if you do use it regularly, it's going to be helpful.



clipped on: 04.01.2013 at 08:02 am    last updated on: 04.01.2013 at 08:02 am

RE: Foliage Pro & Pro Tekt (..AL..) (Follow-Up #4)

posted by: tapla on 11.21.2012 at 04:12 pm in House Plants Forum

If I had to lay out a plan for you, this is what I would say:

* Keep working toward the ability to make a soil that allows you to water with no concern for root issues - no matter how big/small the pot/plant are or what time of the year it is. I easily achieve that with no extraordinary effort, so if you want to, you can too.

* In the meanwhile .... I think most of your plants are small enough that you can lift them easily? Water thoroughly, so at least 10-20% of the water you apply exits the drain. Pour buckets through the pot if you want. Then, hold your pot over the sink and move it up and down. You'll soon discover that when you move the pot downward and suddenly reverse it's direction upward, a big squirt of water will exit the drain. You'll figure it out - first pot. This will remove ALL perched water from your soil, so you needn't worry.

If the plants are too large to carry to the sink, take a look at the picture.


Imagine A as your container at rest, right after you watered. The dark area is the PWT. If you tip the container (B), the PWT will maintain the same ht, but do you see how much water will be removed, just by tipping the pot? C just shows how a container's shape can affect the volume of PW a soil can hold. D illustrates how to use an upside down pot in a larger pot to reduce the volume of PW in a pot, and E shows what a wick can do.

That trick I told you about moving the pot up and down over the sink will really help if you fear your soil is too water-retentive.

* Then, you can fertilize however you wish. If you want to fertilize using a little less than 1/4 tsp of FP/gallon each time you water, you can. If you want to fertilize using a little more than that every other time you water - or, that's fine, too. Getting rid of the perched water frees you up to do a LOT of things you can't do when your soil is too water retentive.

* Finally, keep making an effort to learn. The more you learn, the faster you'll move forward in your abilities. Even if you're an excellent observer, experimenting and relying on experience (trial/error) takes a LOT longer than gathering knowledge and then using your practical experience to validate that knowledge. ..... and keep asking questions.

Happy Thanksgiving!



clipped on: 04.01.2013 at 07:53 am    last updated on: 04.01.2013 at 07:53 am

RE: I'm on board with the Alfalfa, so..... (Follow-Up #25)

posted by: andy10917 on 06.09.2012 at 08:12 pm in Lawn Care Forum

DandyLioness: it's the thing that nobody tells you. The commercial products are basically one-size-fits-all. Which really means "one size fits nobody well".

See that list of nutrients and micronutrients? Well, for a top-quality soil, some of those nutrients should be in a range of 7:1 to 10:1 of each other. And other ones should be in a ratio of 1000:1 to each other. For the ones that are in the range of 7:1 to 10:1 of each other, the soil will act "tight" if it's lower than 7:1 and will be a waster of money if they're more than 10:1. And WHEN they are applied can be an issue too. Some of the nutrients complement each other ("synergistic" - good to add at the same time), and others cancel each other out (antagonistic). Also, raising pH isn't as simple as "add Lime". Which Lime, and how much Potassium (which also raises pH) shortly after the Lime.

It's not something to concern yourself with if you're looking for an OK lawn, but when you want to really hit it out of the park, everything counts. On another website, we get into all the gory little details. If you're interested in that kind of stuff, just google my name, MorpheusPA's name, Tiemco's name.

I'll bet you're sorry you asked, right?


clipped on: 03.31.2013 at 08:52 pm    last updated on: 03.31.2013 at 08:52 pm

Which soil conditioner?

posted by: cyn_s on 04.20.2011 at 08:46 pm in Container Gardening Forum

I have two choices of pine bark fines for making Al's Basic Soil Mix: 1) Nature's Helper Soil Conditioner which is 1/2 fines and 1/2 compost; or 2) Garden Pro Clay Breaker Soil Conditioner which contains gypsum (doesn't say how much).

Can anyone tell me which I should use, and whether I should modify the recipe in any way? THANX!

(Hope these links work!)


clipped on: 03.30.2013 at 07:45 pm    last updated on: 03.30.2013 at 07:45 pm

RE: Supplies by State/Region: Al's Gritty Mix (Follow-Up #135)

posted by: patiogarden_2010 on 05.04.2011 at 10:42 pm in Container Gardening Forum

I found All 3 ingredients for Gritty at Bowen's Farm Supply in Annapolis, Md.

Turface MVP 50lb $11.50
Fine Pine soil conditioner 2CuFt $3.40
Grani Grit Grower 50lb $7.60


clipped on: 03.25.2013 at 12:07 pm    last updated on: 03.25.2013 at 12:07 pm

Supplies by State/Region: Al's Gritty Mix

posted by: greyslate on 04.06.2009 at 07:17 pm in Container Gardening Forum

When starting out looking for the supplies for Al�s Gritty Mix, I ran into some walls. Aided by the indomitable tapla;), I was lucky enough to find everything needed. I thought that we could start a thread in which everyone who is using the Gritty Mix posts where they found supplies � in order to help out new converts in their area. I�ve started with some Maryland information � please follow-up with what you�ve found!

If you�re still looking, and no one�s posted/found supplies in your area, use these tips from tapla:
Grani-grit � "Go to MSN Yellow Pages; Enter Grain Elevator under 'Business name or category'; Enter Location under 'Location'; Call those businesses with 'grain', 'elevator', or 'farming services' after the bold 'category'; Ask for crushed granite grower grit. If they say they have it, be sure it is crushed granite before you head out to pick it up. It might be helpful to ask if it is packaged under the name 'Gran-I-Grit'." I also got lucky looking under "feed suppliers/stores" ...
Turface � Use the website to find local distributors:

State/Region/Province: Maryland (Central/North)
Turface: Newsom Seed Company, locations in Fulton and Gaithersburg (sells by the 50# bag),
Grani-Grit: The Mill, Parkton (Does not normally stock it, but readily orders it for no extra fee; will sell small quantities) (410) 329-6558
Bark fines: "GardenPro, Premium Bark Mulch" from Lowe�s (must be sifted through screens for size, but decent to start with)


clipped on: 03.25.2013 at 10:39 am    last updated on: 03.25.2013 at 10:41 am

Fertilizer Program for Containerized Plants II

posted by: tapla on 03.11.2009 at 11:13 pm in Container Gardening Forum

This subject has been discussed frequently, but usually in piecemeal fashion on the Container Gardening forum and other forums related. Prompted originally by a question about fertilizers in another's post, I decided to collect a few thoughts & present a personal overview.

Fertilizer Program - Containerized Plants II

Let me begin with a brief and hopefully not too technical explanation of how plants absorb water from the soil and how they obtain the nutrients/solutes that are dissolved in that water. Most of us remember from our biology classes that cells have membranes that are semi-permeable. That is, they allow some things to pass through the walls, like water and select elements in ionic form dissolved in the water, while excluding other materials like large organic molecules. Osmosis is a natural phenomenon that is nature�s attempt at creating a balance (isotonicity) in the concentration of solutes in water inside and outside of cells. Water and ionic solutes will pass in and out of cell walls until an equilibrium is reached and the level of solutes in the water surrounding the cell is the same as the level of solutes in the cell.

This process begins when the finest roots absorb water molecule by molecule at the cellular level from the surface of soil particles and transport it, along with its nutrient load, throughout the plant. I want to keep this simple, so I�ll just say that the best water absorption occurs when the level of solutes in soil water is lowest, and in the presence of good amounts of oxygen (this is where I get to plug a well-aerated and free-draining soil), ;o). Deionized (distilled) water contains no solutes, and is easiest for plants to absorb. Of course, since distilled water contains no nutrients, using it alone practically guarantees deficiencies of multiple nutrients as the plant is shorted the building materials (nutrients) it needs to manufacture food, keep its systems orderly, and keep its metabolism running smoothly.

We already learned that if the dissolved solutes in soil water are low, the plant may be well-hydrated, but starving; however, if they are too high, the plant may have a large store of nutrients in the soil, but because of osmotic pressure, the plant may be unable to absorb the water and could die of thirst in a sea of plenty. When this condition occurs, and is severe enough (high concentrations of solutes in soil water), it causes fertilizer burn (plasmolysis), a condition seen when plasma is torn from cell walls as the water inside the cell exits to maintain solute equilibrium with the water surrounding the cell.

Our job, because you cannot depend on an adequate supply of nutrients from the organic component of a container soil, is to provide a solution of dissolved nutrients in a concentration high enough to supply nutrients in the adequate to luxury range, yet still low enough that it remains easy for the plant to take up enough water to be well-hydrated and free of drought stress. Electrical conductivity (EC) of, and the level of TDS (total dissolved solids) in the soil solution is a reliable way to judge the adequacy of solutes and the plant�s ability to take up water. There are meters that measure these concentrations, and for most plants the ideal range of conductivity is from 1.5 - 3.5 mS, with some, like tomatoes, being as high as 4.5 mS. This is more technical than I wanted to be, but I added it in case someone wanted to search "mS" or "EC". Most of us, including me, will have to be satisfied with simply guessing at concentrations, but understanding how plants take up water and fertilizer, as well as the effects of solute concentrations in soil water is an important piece of the fertilizing puzzle.

Now, some disconcerting news - you have listened to all this talk about nutrient concentrations, but what do we supply, when, and how do we supply them? We have to decide what nutrients are appropriate to add to our supplementation program, but how? Most of us are just hobby growers and cannot do tissue analysis to determine what is lacking. We can be observant and learn the symptoms of various nutrient deficiencies though - and we CAN make some surprising generalizations.

What if I said that the nutritional needs of all plants is basically the same and that one fertilizer could suit almost all the plants we grow in containers - that by increasing/decreasing the dosage as we water, we could even manipulate plants to bloom and fruit more abundantly? It�s really quite logical, so please let me explain.

Tissue analysis of plants will nearly always show NPK to be in the ratio of approximately 10:1.5:7. If we assign N the constant of 100, P and K will range from 13-19 and 45-70 respectively. (I�ll try to remember to make a chart showing the relative ratios of all the other 13 essential nutrients that don�t come from the air at the end of what I write.) All we need to do is supply nutrients in approximately the same ratio as plants use them, and in adequate amounts to keep them in the adequate to luxury range at all times.

Remember that we can maximize water uptake by keeping the concentrations of solutes low, so a continual supply of a weak solution is best. Nutrients don�t often just suddenly appear in large quantities in nature, so the low and continual dose method most closely mimics the nutritional supply Mother Nature offers. If you decide to adopt a "fertilize every time you water" approach, most liquid fertilizers can be applied at � to 1 tsp per gallon for best results. If you decide that�s too much work, try halving the dose recommended & cutting the interval in half. You can work out the math for granular soluble fertilizers and apply at a similar rate.

The system is rather self regulating if fertilizer is applied in low concentrations each time you water, even with houseplants in winter. As the plant�s growth slows, so does its need for both water and nutrients. Larger plants and plants that are growing robustly will need more water and nutrients, so linking nutrient supply to the water supply is a win/win situation all around.

Another advantage to supplying a continual low concentration of fertilizer is it eliminates the tendency of plants to show symptoms of nutrient deficiencies after they have received high doses of fertilizer and then been allowed to return to a more favorable level of soil solute concentrations. Even at perfectly acceptable concentrations of nutrients in the soil, plants previously exposed to high concentrations of fertilizer readily display these symptoms.

You will still need to guard against watering in sips, and that habit�s accompanying tendency to allow solute (salt) accumulation in soils. Remember that as salts accumulate, both water and nutrient uptake is made more difficult and finally impaired or made impossible in severe cases. Your soils should always allow you to water so that at least 10-15% of the total volume of water applied passes through the soil and out the drain hole to be discarded. This flushes the soil and carries accumulating solutes out the drain hole.

I have recently switched to a liquid fertilizer with micronutrients in a 12:4:8 NPK ratio. Note how closely this fit�s the average ratio of NPK content in plant tissues, noted above (10:1.5:7). If the P looks a little high at 4, consider that in container soils, P begins to be more tightly held as pH goes from 6.5 to below 6.0, which is on the high side of most container soil�s pH, so the manufacturer probably gave this some careful consideration. Also, P and K percentages shown on fertilizer packages are not the actual amount of P or K in the blend. The percentage of P on the package is the percentage of P2O5 (phosphorous pentoxide) and you need to multiply the percentage shown by .43 to get the actual amount of P in the fertilizer. Similarly, the K level percentage shown is actually the level of K2O ( potassium oxide) and must be multiplied by .83 to arrive at the actual amount of K supplied.

To answer the inevitable questions about specialty fertilizers and "special" plant nutritional requirements, let me repeat that plants need nutrients in roughly the same ratio. Ratio is an entirely a separate consideration from dosage. You�ll need to adjust the dosage to fit the plant and perhaps strike a happy medium in containers that have a diversity of material.

If nutrient availability is unbalanced - if plants are getting more than they need of certain nutrients, but less than they need of others, the nutrient they need the most will be the one that limits growth. 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 nutrient will the plant growth increase. There is also an optimum combination?ratio of the nutrients and increasing them, individually or in various combinations, can lead to toxicities.

When individual nutrients are available in excess, it not only unnecessarily contributes to the total volume of solutes in the soil solution, which makes it more difficult for the plant to absorb water and nutrients, it also often creates an antagonistic deficiency of other nutrients as toxicity levels block a plant's ability to take up other nutrients. E.g., too much Fe (iron) can cause a Mn (manganese) deficiency, with the converse also true, Too much Ca (calcium) can cause a Mg (magnesium) deficiency. Too much P (phosphorous) can cause an insoluble precipitate with Fe and make Fe unavailable. It also interferes with the uptake of several other micro-nutrients. You can see why it�s advantageous to supply nutrients in as close to the same ratio in which plants use them and at levels not so high that they interfere with water uptake. I know I�m repeating myself here, but this is an important point.

What about the high-P "Bloom Booster" fertilizers you might ask? To induce more prolific flowering, a reduced N supply will have more and better effect than the high P bloom formulas. When N is reduced, it slows vegetative growth without reducing photosynthesis. Since vegetative growth is limited by a lack of N, and the photosynthetic machinery continues to turn out food, it leaves an expendable surplus for the plant to spend on flowers and fruit. Plants use about 6 times more N than P, so fertilizers that supply more P than N are wasteful and more likely to inhibit blooms (remember that too much P inhibits uptake of Fe and many micro-nutrients - it raises pH unnecessarily as well, which could also be problematic). Popular "bloom-booster" fertilizers like 10-52-10 actually supply about 32x more P than your plant could ever use (in relationship to how much N it uses) and has the potential to wreak all kinds of havoc with your plants.

The fact that different species of plants grow in different types of soil where they are naturally found, does not mean that one needs more of a certain nutrient than the other. It just means that the plants have developed strategies to adapt to certain conditions, like excesses and deficiencies of particular nutrients.

Plants that "love" acid soils, e.g., have simply developed strategies to cope with those soils. Their calcium needs are still the same as any other plant and no different from the nutrient requirements of plants that thrive in alkaline soils. The problem for acid-loving plants is that they are unable to adequately limit their calcium uptake, and will absorb too much of it when available, resulting in cellular pH-values that are too high. Some acid-loving plants also have difficulties absorbing Fe, Mn, Cu, or Zn, which is more tightly held in alkaline soils, another reason why they thrive in low pH (acid) soils.

So, If you select a fertilizer that is close in ratio to the concentration of major elements in plant tissues, you�re going to be in good shape. Whether the fertilizer is furnished in chemical or organic form matters not a whit to the plant. Ions are ions, but there is one major consideration. Chemical fertilizers are available for immediate uptake while organic fertilizers must be acted on by passing through the gut of micro-organisms to break them down into usable elemental form. Since microorganism populations are affected by cultural conditions like moisture/air levels in the soil, soil pH, fertility levels, temperature, etc., they tend to follow a boom/bust cycle in container culture, which has an impact on the reliability and timing of delivery of nutrients supplied in organic form. Nutrients locked in hydrocarbon chains cannot be relied upon to be available when the plant needs them. This is particularly an issue with the immobile nutrients that must be present in the nutrient stream at all times for the plant to grow normally.

What is my approach? I have been very happy with Miracle-Gro 12-4-8 all purpose liquid fertilizer, or 24-8-16 Miracle-Gro granular all-purpose fertilizer - both are completely soluble. I incorporate a granular micro-nutrient supplement in my soils when I make them (Micromax) or use a soluble micro-nutrient blend (STEM). I would encourage you to make sure your plants are getting all the micro-nutrients. More readily available than the supplements I use is Earth Juice�s �Microblast�. Last year, I discovered a fertilizer by Dyna-Gro called Foliage-Pro 9-3-6. It is a 3:1:2 ratio like I like and has ALL the primary macro-nutrients, secondary macro-nutrients (Ca, Mg, S) and all the micro-nutrients. It performed very well for me.

When plants are growing robustly, I try to fertilize my plants weakly (pun intended) with a half recommended dose of the concentrate at half the suggested intervals. When plants are growing slowly, I fertilize more often with very weak doses. It�s important to realize your soil must drain freely and you must water so a fair amount of water drains from your container each time you water to fertilize this way. This year my display containers performed better than they ever have in years past & they were still all looking amazingly attractive at the beginning of Oct when I finally decided to dismantle them because of imminent cold weather. I attribute results primarily to a good soil and a healthy nutrient supplementation program.

What would I recommend to someone who asked what to use as an all-purpose fertilizer for nearly all their container plantings? If you can find it, a 3:1:2 ratio soluble liquid fertilizer (24-8-16, 12-4-8, 9-3-6 are all 3:1:2 ratio fertilizers) that contains all the minor elements would great.

How plants use nutrients - the chart I promised:

I gave Nitrogen, because it's the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.
N 100
P 13-19 (16) 1/6
K 45-80 (62) 3/5
S 6-9 (8) 1/12
Mg 5-15 (10) 1/10
Ca 5-15 (10) 1/10
Fe 0.7
Mn 0.4
B(oron) 0.2
Zn 0.06
Cu 0.03
Cl 0.03
M(olybden) 0.003
To read the chart: P - plants use 13-19 parts of P or an average of about 16 parts for every 100 parts of N, or 6 times more N than P. Plants use about 45-80 parts of K or an average of about 62 parts for every 100 parts of N, or about 3/5 as much K as N, and so on.

If you're still awake - thanks for reading. It makes me feel like the effort was worth it. ;o) Let me know what you think - please.

Here is a link to the first posting of A Fertilizer Program for Containers

Another link to information about Container Soils- Water Movement and Retention


clipped on: 03.25.2013 at 10:39 am    last updated on: 03.25.2013 at 10:41 am