Container Soils: Water Movement and Retention II

I agree!
That's why this thread has taken on a life of it's own!

I could cry - I just spent a half hour typing a reply to several of the posts & I lost the whole thing when I tried to upload it. ;o( Well - back to work ....

Al

I'll try again. ;o)

Melissa - I use either pine or fir bark in all my houseplant soils (no peat at all) so I know that it works well. If you feel the product you have is too small, keep looking for something like in the pic I'll supply at the bottom, or if you have a friend with a chipper, perhaps you could beg him/her to process it to a little finer mesh for you?

I don't often start seeds, but for the few that I do, I use Turface, straight from the bag. Since I always screen my components for bonsai soil, I always have plenty of Turface fines on hand & I cover the seeds with that. It's really hard to beat the jiffy sterile seed starting blends of peat & vermiculite though. They work well, even if they do collapse quickly.

I'll talk a little about EC (electrical conductivity) and TDS (total dissolved solids). They're a measure of what is dissolved in our soil water, so a high level of salt in coir would contribute to elevated levels. I'll explain why this is bad.

Plants take up water best when there are no ions in it - nothing dissolved - no fertilizer - just distilled water. But we cannot do that, or they will starve. We need to add nutrients. There is a fairly narrow band of TDS and EC that is ideal for plants, and it varies by light intensity, temperature, growth rate, and where the plant is in the growth cycle. On the flip side of the coin, if the level of TDS and EC is too high, the plant cannot absorb either water or nutrients, so it could starve or die of thirst in a sea of plenty.

We generally consider the TDS and EC to be an indicator of nutrient levels, but accumulating salts from fertilizers & irrigation water, play an important part, as would latent salts in a coir product (for example). If you want to fertilize at a solution strength of 1,500 ppm, and there is already 700 ppm of accumulated salts in the soil, that means you would only be able to add a solution containing 800 ppm or you would exceed your self-imposed solution strength and possibly create problems in the plants ability to absorb water & nutrients.

I'm not trying to impress you with numbers - pay no attention to them except to help you realize that there is a "ZONE" we hope we can stay in through educated guessing so our plants are at least somewhere between starved & burned up. ;o)

When TDS and EC levels get extremely high, water can be "pulled" from plant cells in exactly the same way that moisture is pulled from ham and bacon. The scientific term for this is plasmolysis, but you and I know it commonly as fertilizer burn.

Ok - now we know there is a zone. We also need to realize that it's important to maintain the right mix of elements and stay within that zone. Why is this important? Well, if you're using the popular 10-52-10 "bloom boosting" blend that's oft touted, you're prolly applying around 30 times more P than the plant can possibly use (in relation to N). You could be fertilizing at the correct zone of TDS & EC, but the extremely high levels of P would automatically guarantee a N deficiency.

I'm going to stop here so you can catch up & absorb this - it's important to understand. I'll leave a pic for Melissa see if there are any questions.

Al

This message was edited Jan 25, 2008 8:58 PM

This message was edited Jan 25, 2008 9:02 PM

Al - in the last line of the next to last paragraph, don't you mean 'extreme high levels of P would...'?

Al, I do have a question- is Advil, asprin or Tylenol better for a headache..? ;0) Maybe I should forget the return to college thing. Belive me, all you have to do is add 2+2 to impress me w/ numbers.

One request I have is to put a coin or something in that photo for scale. I'm going to seek out your "Golden Trophy" fines- are they in that picture?

I'll have to rent my own chipper, sadly. Everyone I know thinks I'm a "plant freak"! I. e., they don't garden and can't understand how plants take over your life. Like cats.

I buy dry fertilizer by the bag in "one third" amounts: one being 10-0-0, another 0-10-0, and 0-0-10 (rounded off amounts), and adjust it depending on what I'm fertilizing- this is for my 2.5 acres of trees, grass, perennials, annuals, weeds, and more weeds. I use bags of organic greensand, dried blood, phosphate, muriate of potash, etc. Maybe this is a mistake? To be honest, I don't often fertilize my indoor plants. I don't know what to use.

I'm so confused... hey, it's Friday night/Sat. am and I'm here obsessing about my container plants for this spring, with my cat, Jax, in my lap. Things are worse than I thought!!!!

First, you're almost totally responsible for supplying nutrients to your plants in container culture. Container culture is completely different from growing in the garden, and is much closer to hydroponics than garden culture. I think you'd do well to forget the granular fertilizers, except in isolated cases & only then if you're well-versed in what you're doing. I'll probably get all kinds of flack for saying this, but I'm equipped & ready to debate this point: If you're confused about fertilizers for container plantings - all you really need to know is that the closest ratio on the market to what plants ACTUALLY use is 3:1:2 - N:P:K. That isn't the % of NPK - it's the ratio. The two fertilizers you should look for are: 24-8-16 or 12-4-8. Miracle gro makes both in easy-to-use granular/soluble, or liquid, and they come with some of the micronutrients. I use them by choice on 99% of my plants & I have a broad diversity of plant material - especially in summer. If you're at all unsure of how to tweak your nutrient supplementation program, you won't go far wrong if you use this formula for everything. It's been around for years & there's a good reason that MG labels it as "All-Purpose Fertilizer".

http://www.miraclegro.com/index.cfm/event/ProductGuide.product/documentId/637153cfaa6b1ff545c0236933b0a7a4 Miracle-Gro Granular soluble 24-8-16 with micronutrients. Click on "read label" for more info

http://www.scottscanada.ca/index.cfm/event/ProductGuide.product/documentId/8AA325CB3201B064850BAC15135A32E0 Miracle-Gro liquid 12-4-8 with micronutrients. Click on read label for more info. This is what I use almost always.

Al

The term "well-versed" resonnates with me. How does one become well-versed? There is more snake oil being sold to us "serious hobby" gardeners than botox to LA housewives. Is there a good reference book?

I guess my "fertilization program" (I don't have one) works like a broken clock: It will be correct 2 times out of 12 simply by default.

I am going to read up on hydroponics. I don't know a bit about it.

I wouldn't debate you on fertilizers, BUT I would love to hear the argument! I will go so far as to ask "How can one fertilizer be all purpose?" Right now, I have 6 bougainvillea and 5 geraniums that are "overwintering" (they aren't actively growing- waiting to put them outside); A dozen or so Sansevieras (I collect them), 5 spider plants, a dozen succulents or so, and a philodendron. I haven't fertilized any of them; they are in your recipe w/ the CRF plus a micronutrient powder. I feel the recipe had enough nutrients, but should I be supplementing them? (I also have 2 Golden Dragon clivia. They are dying. I kill all clivia; I don't know how I do this!)

Al, make it easy on yourself and write a book to go along with your pre-packaged fertilizer!!! I'll buy it!!!

Jax4ever, just print off this entire thread and the one that goes with it. You'll have your book. I have read and reread both threads and slowly the light is dawning. I agree, it would be nice to be able to purchase prepackaged planting mix from Al, but I don't think we are going to get off this easy. Good luck with your houseplants. Dotti

Melissa - First - it's pretty much a must, that you supplement a containerized planting if you expect it to grow w/o nutritional deficiencies, so the sooner you settle on some kind of a nutritional supplementation program for your houseplants & others in containers, the happier both you and your plants will be. ;o)

Second - I promise I'll do my best to never peddle "snake oil" to you. I try to make sure that everything I say here is firmly rooted in plant physiology or one of the sciences, and that I can always call on science to reinforce my observations and opinions.

I'm not sure how you'd become well-versed in the physics of container soils, I kind of did that on my own, but as far as physiology, plant husbandry, fertilization, that sort of thing, good quality text books abound & they're all filled with as much knowledge as we can possibly absorb. If you're really interested, I'll name a few, but I think they would be pretty dry & technical to suit most tastes. Let me know ...?

You said you haven't fertilized and wondered "How can one fertilizer be all purpose?"

Well, look carefully at the chart I made. It shows the range of nutrients found in the living tissues of almost all plants. 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

How to interpret the chart: The first set of numbers is the range of the nutrient as it occurs in plant tissues for every 100 parts of N. So there are 13-19 parts of P, and 45-80 parts of K in plant tissues for every 100 parts of N. The second number, in parenthesis, is simply the average number for the range. Be patient - this is going somewhere. ;o) So, plants average 16 parts of P and 62 parts of K for every 100 parts of N. The last number, the fraction, represents how much of each nutrients are in living tissues when compared to N. There is approximately 1/6 the P and 3/5 the K in living plant tissues as there is N.

If we want to see how these averages compare to the 3:1:2 ratio of fertilizer I suggested above, we need to only divide the value of all the averages by 3.33. if we divide 100:16:62 by 3.33, we come up with approximately a ratio of 3:.5:2 - N:P:K that is actually IN plant tissues. This is extremely close to the 3:1:2 ratio I suggested, and even though it is still a little high in P, plants will tolerate it well, From this you can do a few calculations and see that a 20-20-20 blend supplies (on average) about 6 times more P than plants could ever use, and almost twice the K.

This chart, based on a % of N is the basis of how commercial greenhouse fertigation programs are structured. They determine how much N is needed, and all the other nutrients are added as a % of N. When commercial operations fertilize, they often use sophisticated tissue analysis to determine which of the three primary macronutrients, secondary macronutrients (magnesium, calcium, sulfur), and/or micronutrients are in tissues in excess, or are deficient. When they are deficient, they will adjust the fertigation program to raise the level of that nutrient in tissues to the proper range - the opposite for excesses. If tissue analysis shows there is no deficiency or excess, all is well (unless there is intentional manipulation of nutrients to achieve a specific end - often the rule) and the blend will be very close to the 3:1:2 blend mentioned above

Since we, as hobby growers, haven't the wherewithal to track our plant's nutritional needs so closely, we need to take an informed shotgun approach. Since plants use the major nutrients in very close to a 3:1:2 ratio of N:P:K, doesn't it make sense to supply those nutrients in as close to that exact ratio as possible? I'll be bold & answer that question for you - YES, of course it does. ;o)

Al


This message was edited Jan 26, 2008 9:32 PM

Al: Is Miracle-Gro liquid 12-4-8 with micronutrients available in the US? I'm not seeing in on their website.

Al: Starting with your comments: "From this you can do a few calculations and see that a 20-20-20 blend supplies (on average) about 6 times more P than plants could ever use, and almost twice the K....Since plants use the major nutrients in very close to a 3:1:2 ratio of N:P:K, doesn't it make sense to supply those nutrients in as close to that exact ratio as possible?"
Aside from the inefficiency of adding too much P and K when using an NPK ratio of 1-1-1, if your tissue analysis shows that the plants have the proper ratio of 3:1:2 when using a 1-1-1 formulation, there's no problem. Somewhere along the line, the plant's physiology will come into play, as well. It may be that a 3-1-2 NPK mix in your fertilizer is more in keeping with what you want your plant to have, but not to the point that a good general purpose nutrient, sensibly applied, wouldn't be a good choice.

Al, THANK YOU for the information. I would like a text book reference or 2.

I didn't mean that you would peddle snake oil! It's just that every gardening catalog that I recieve has a new and better fertilizer- bat guano, seaweed, worm castings, sewage from lake Michigan- all will make your plants bigger and better that last year's concoction. Oh, by the way, to get the most from our new fertilizer, you simply must buy the wetting agent, the innoculent, the super-duper sprayer, the bio-enzymes, the micro-nutrients or the fertilizer won't work and here's a picture of the plant grown WITH our products and one without... impress your neighbors... blah, blah, blah...

In other words, the sellers of all this stuff are preying on our ignorance about chemistry and what our soil (container or not) is currently missing. I don't understand your calculations- yet. I'm going to re-read it; you taught me about the PWT and I got THAT after a couple of read-throughs. I really appreciate you taking the time to type all of this out for us. And I'm glad there are other knowledgable people out there asking tough questions!!! It's going to save me lots of $$$ on unicorn manure or whatever else is new this year...

I-guy - Since (with a few exceptions like tropical hibiscus) plants use more N than any other element, fertilizer under controlled conditions is applied as a function of the amount of N used. It's indisputable that plants use approximately 6 times more N than P, and about 1.5 times more N than K. If we apply a 1:1:1 fertilizer at a rate that guarantees no N deficiency, we are automatically applying 6 times more P and 1.5 times more K than the plant will use.

I'm not saying that you can't have perfectly healthy plants by using a 1:1:1 ratio judiciously, but it does hamper your ability to apply more fertilizer when a N deficiency becomes apparent, and limits o/a flexibility. I won't say that a 1:1:1 blend cannot be a good choice, but I will say that with an extremely high % of plant material, a 3:1:2 blend is a better choice.

For example: In weekly fertilizing of geraniums, N should be applied at 480 ppm. If we want to limit our TDS level of our fertilizer water to 1,500 ppm (a very realistic goal), using a 1:1:1 blend, we have 480 ppm each of NPK or 1,440 ppm of JUST those 3 elements. If we add in 250 ppm for TDS in the water and another 250 ppm for micronutrients (both conservative), we're already well over our limit (1,940 ppm) & into the range where we may be inhibiting water & nutrient uptake because of elevated EC and TDS levels.

If we applied a 3:1:2 ratio fertilizer, we supply all the N the plant needs, all the other secondary macronutrients, all the micronutrients, have allowed for water hardness, and we still come in at 1,460 ppm - room to spare if we needed to correct for a nutritional deficiency.

Our goal should be to keep all nutrient levels in soil solution somewhere between "adequate" and "luxury" levels. At the same time, we want to keep the level of TDS and EC at it's lowest while supplying those nutrients. Using a 1:1:1 ratio fertilizer like 12-12-12 or 20-20-20 inhibits our ability to maintain luxury levels AND to minimize the level of TDS and EC.

I mentioned hibiscus in my opening comment because it's one of the few plants that prefers a little more K than N in its diet. I compensate for this by adding a tbsp of potash (supplies K) per gallon of soil when I pot/repot and still use a 3:1:2 ratio fertilizer.

Melissa - I knew that you didn't mean anything offensive & I was smiling as I mentioned the snake oil. I didn't take any offense. ;o)

If you want to learn about soil composition and fertilization, I'll suggest a very good and reasonably easy to understand text: Water, Media, and Nutrition for Greenhouse Crops - edited by David Reed, published by Ball Publishing ISBN 1-883052-12-2

Here is an excellent online source for info on plant physiology, listed by subject. http://4e.plantphys.net/categories.php?t=t It should keep you busy until the book comes. ;o)

Take care.

Al

Al, is this your hobby or profession?
I know you grow bonsai, but what else?
AND if you can figure out a way to bottle sunshine (the lack thereof being a huge problem for me), let me know. With your knowledge, I bet you can figure it out ;0) (Actually, switching every home light to flourescent has helped my plants immeasurably. They get less intense light, but I tend to keep the lights on more than 18 hrs. a day.)

Hi Melissa - I'll answer your questions, but then as gently as possible I'll ask everyone if we can try to stay focused on container soils & try not to get too conversational about off topic stuff? I'm only asking that so other readers don't have so much trouble loading the thread and wading through our off-topic conversations. I'd love to visit with anyone who wants to talk by D-mail or e-mail though? Please don't be offended. Even the fertilizer conversation is a little off-topic, but I think it ties into soils well enough that those coming to the thread for soil info could gain from reading through it?

This is all hobby for me. I get to talk to lots of growers & people from all over the world (this summer I helped a parks guy from Paris, France build a soil for their street tree plantings). Mostly they find me through surfing the net when something I've written on Dave's or GW comes up. Almost everything I've learned has been an outgrowth of my chase for knowledge that applies to the art of bonsai. If I have strengths, I'd probably say they are in soil science and plant physiology.I have several gardens & raised beds, around 200 woody plants in containers that are future bonsai candidates, a bunch of more unusual houseplants, and I do a ton of containers for display throughout the gardens & deck in the summer. I own a glazing contracting business (glass company) and I'm old enough to be a grandpa. ;o)

Ok - back to soil-related talk now .....

Al

Al: Attached is a tissue analysis taken from a sample of 20,000 geraniums grown several years ago using a 12-12-12 mixture of a dry granular product applied at a rate of 5 pounds per cubic yard, single application, no subsequent feeding. The analysis was taken after 4 weeks' growth from unrooted cuttings. If my math is correct, that translates into an application of N, P and K of about 272 grams throughout the growing media. By the time I visited the greenhouse in early February, the plants were shooting buds like mad. I'll not dispute any of your assertions as to the proper levels of nutrient needed for healthy plant development, because you're absolutely on the money. My point is that by delivering nutrient in the most efficient means possible, you're capable of growing an outstanding plant (in this case, geranium) with a minimum of actual nutrient being delivered. This gives the grower much wider latitude to supplement at a much lower overall rate without over-application if amendment of the feeding is needed. I have trials on tomato and petunia which offer similar findings, but I thought you 'd be interested in seeing the geranium results attached.

The last post showed the media analysis of the same trial. Here's the tissue analysis. Sorry about that.

In your estimation and after reviewing the media analysis - if you had to choose between a 3:2:1 blend and a 1:1:1 blend, which would you choose for the next supplementation?

I'm aware that most greenhouse applications normally use something closer to a 2:1:2 blend as a starter mix, and this grower is intentionally keeping N levels low to slow vegetative growth and keep the plants compact as buds form, but we're really talking about post production plants in this thread. If you wanted to bring the extremely low levels of N in the media sample up to where they should be for the plants readers are growing in containers, using a 1:1:1 blend would drive P levels through the roof, which will start interferring with both Fe and Mn uptake.

I'll leave you space for the last word & perhaps then we can get back to something everyone can participate in. ;o) I'm pretty sure that most readers are pretty disinterested in joining in our debate.

Al

So where can one buy 3:2:1 ?

TLC (I like that) - 3:1:2 is only the ratio of the primary nutrients. Examples of the two most common fertilizers that have this ratio are Miracle-Gro 24-8-16 granular/soluble and Miracle-Gro 12-4-8, both with micronutrients.

See Post #4455506 a little way up this thread for links to the product description and a look at what the package looks like.

Al

I am surprised by how low a PH that grower had his geraniums at. 5.88 is pretty low for geraniums.

Forgive me for continuing the fert discussion, but I think that this question/clarification ties in nicely with container grown plants. Did I understand you correctly when I thought that you said that you don't think that slow release fertilizers work well in containers? Just went back and reread what you said-that one would do well to forget slow release ferts except in isolated situations. Just wondering why you felt that way.
I think it would be a good time to discuss the pros and cons of slow release to soluble ferts in containers as one has to do one or the other,in most cases, in order to provide nutrition. I love using slow release in my containers, saves me a lot of time and gives me a break from foliar fertilizing which is so time consuming in comparison to watering.
This is absolutely your thread but I think it would be good to cover the different types of slow release and amts used etc.

TL - can you give me a post# please? I'd like to read the context in which I might have said that. It could well have had something to do with timing of the application or another issue a poster might have mentioned. I think the basic recipes I posted at the top of the thread allowed for the inclusion of CRFs, but that doesn't mean they are either appropriate or inappropriate at all times. ;o)

Never mind - I found it. I said "granular" fertilizers. Are you referring to Controlled Release Fertilizers like Osmocote, or the granular fertilizers I was referring to?

Al

Well thank you for the link but when I clicked on product information it said it was 15-30-15

But I googled and found it here;

http://underbid.com/action/display/item/20640-1061876216/sku/701356.html

My fertilizing has been hit and miss; in the Spring, as soon as the snow is gone I sprinkle Osmocote all over. Then I fertilize every time I water at half strength, switching from MG, to Seaweed Extract, to Epsom Salts, to Peters 20-20-20, to Mighty Plant, to fish emulsion. On the off weeks I sprayed with Messenger.

I didn't really know what to use so I switched around. I will order this and see if using it this summer makes a difference. I was never really sure if what I was doing was helping or harming.

I appreciate the effort you have put into this post and what I have gleaned from it simply is to try 24-8-16. Now I just need to figure out what to use on my potted tropical hibiscus that I overwinter.

One last question and then I'll go away; is it true that you shouldn't fertilize your over wintered plants.

Thank you for your effort in explaining all this; it will make us better gardeners.

arlene

I'll finish off my contribution to this thread by saying I've used the same product in my geraniums at home as were used to start the plants in the trial (actually, I took some of those very plants 4 years ago), and they've been going strong, giving great blooms, ever since. I'll be looking for that CRF thread.

TLC asks: "One last question and then I'll go away; is it true that you shouldn't fertilize your over wintered plants."

To answer the question, I would need to qualify the response. There is usually no real need to fertilize dormant deciduous plants. For conifers taking a cold quiescent (resting) break, there is some advantage in maintaining a low level of the full compliment of nutrients necessary for growth, simply because the plant is capable of some growth while over-wintering in a cold place.

Houseplants and other (usually perennial) plants that are not truly dormant (they may be resting in a cool place) go about the business of living and adjusting their metabolic needs according to certain internal rhythms (search circadian and endogenous rhythms for more info) and cultural conditions. Their internal clocks and lowered light levels are key factors in the marked slowdown most of us observe in our plants in winter; however, slowed growth cannot simply be offered up as proof of "dormancy". Just because we can't see plants growing or we think they are not growing is insufficient cause for certainty in the matter. In fact, in winter, our houseplants are carrying on photosynthesis and respiration - keeping their systems orderly, and going about their metabolic processes in a "business as usual" manner. They are just doing it at a much-reduced rate.

Why then, would we deprive plants of the building blocks they need (fertilizer) to produce the energy (make food) to carry on their metabolism? In nature, do the nutrients just disappear from soils whenever a plant's internal clock or cultural conditions cause slowed growth? Of course not - and the idea is absurd. Even if you cannot SEE plants growing, they are STILL producing and storing photosynthate to be used in a later push of (spring?) growth. Withholding fertilizer, LIMITS the plants ability to carry on this important part of its growth cycle. Plants are efficient users of nutrients, but they cannot make something from nothing.

If you were striving for ultimate growth and best vitality, it would be REQUIRED that plants should ALWAYS have a full compliment of ALL the nutrients essential for growth in a solution strong enough to supply all nutrients in the adequacy range, but not so strong that it makes it osmotically difficult for the plant to absorb water and nutrients. This bold part is key.

The reason it is so often parroted that we should refrain from fertilizing in winter isn't because the practice itself is bad for plants (simple science and a little knowledge of plant physiology is all that's needed to dispel that myth); it's because so many of us are growing in a soil that simply will not allow us to fertilize in a way that is best for the plants.

Remember, I'm often at odds with growers who support a practice out of convenience or a necessity based on cultural limits they have either placed on themselves or that they must work within. Soo often you'll find me saying that grower convenience and plant vitality are often at odds with each other and are often mutually exclusive.

Where am I headed? Well, if we KNOW that availability of low levels of all nutrients at all times is best, even in winter, why are we so often admonished against winter fertilizing? It's because of the soils we use. Even without the addition of fertilizer to our irrigation water, the level of salts and total dissolved solids (TDS) in our soils (for most of us) continues to accumulate over winter because of watering habits necessitated by slow soils. Some limit themselves by soil choice and then try to tell others that ARE using a soil that allows them to fertilize appropriately that they are doing something wrong. This, because the some lack adequate understanding about what is really happening with regard to plant's actual nutritional needs.

So YES, many readers are limited to being unable to fertilize adequately because of soil choice, and just because plants carry through winter w/o additional fertilizer supplements over the dark months, is not an indication of anything except that plants will usually tolerate it. Is it the end of the world if you don't fertilize in winter - or you can't? Not really, but you can see that there really is a better way than simply withholding nutrients from an already stressed plant.

Dr. Alex Shigo: " ... correct the stress, which will lead to strain, that if uncorrected will lead to the death of the organism."

As you might guess if you've followed this thread, I use fast soils that drain freely & I fertilize with my own concoction (which is basically MG 12-4-8 with micronutrients + some STEM + some Sprint 138 Fe chelate [an iron supplement for high pH water applications] + MgSO4 + vinegar) at EVERY watering, and it works extremely well for the plants I over-winter. For winter watering, when I add the TDS of my water and what I add to it, I'm applying the right mix of nutrients at every watering at a rate of less than 300 PPM of TDS which puts me on very sound horticultural ground. In summer, the same plants will be fertilized at somewhere near the rate of 1,500 - 1,800 PPM weekly - a big difference.

I'm not suggesting that you adopt a "fertilize at every watering" routine like I have, but there is no reason that you cannot fertilize regularly during the winter if you're using a well-aerated and fast draining soil. If you're using a slow, water-retentive soil that necessitates your watering in "sips" instead of watering copiously and flushing the soil at every watering, the salt build-up from irrigation water and fertilizer increases the risk factor for elevated levels of TDS and EC and eliminates your ability to make sure the right nutrients are available in the right proportions.

Tip: Often, around this time of year (Feb usually) when you think your plants are suffering because of low humidity levels in your home, what actually is happening is this: You've been watering in sips, maybe even fertilizing a few times since last Fall, so almost ALL the fertilizer salts and metal salts dissolved in your irrigation water have accumulated in the soil. If you read the post upthread that explains that high levels of salts in the soil (EC & TDS) inhibits the plants ability to absorb nutrients and water, you'll understand that though humidity is probably playing a part in the plant's suffering, it's more likely you should attribute the suffering to a poor soil and accumulating salts in that soil because you risk root rot if you flush the soil at each watering.

Take good care.

Al

Tapla
What’s your opinion on rice hulls? Do you think that it could be used instead of perlite?

Thank you soooo much

Oldude - IMO, rice hulls should only be used in container soils destined for extremely short-term plantings & probably not in the place of perlite, rather - as a replacement for, or an addition to other organic components. Rice hulls are primarily cellulose, so you should expect two things from them - a rather rapid structural breakdown and the accompanying Nitrogen immobilization associated with the breakdown - something similar to what you would expect from coarse sapwood sawdust.

Al

Thank you Al, for all of your information and work. I do a lot of gardening in containers and you have made clear to my why some of my methods have been working better than others, and given me some good clues on improving my methods for other plants.

I usually use a 3 gallon pot, with the bottom third filled with oak leaves and decayed wood chips. The top is a mix of spent mushroom dirt peat and pearlite. If I am growing a root vegetable, I use vermiculite instead of pearlite, as I find the occasional glass powder included in my vegetables unappealing. I add crushed limestone, greensand, and the granite grains used for chickens, to maintain the nutrients that wash out easily. Every once in a while, I test my soil, and rarely find that it needs a fertilizer to maintain a good concentration of ambient nutrients. I will at times have to add some iron or more crushed limestone.

I tend to grow in two tiers. The tougher, more competitive plants I grow around the pot, and the more tender plants I grow in the pot. This way, the water I use gets used twice.

Onions, Corn, Carrots, Radishes, Lettuce, Basil, and Tomatoes seem to thrive in this environment, Squash do well but then loose vigor, Legumes never quite produce more than enough to replant, and Thyme does well for a while and then gives up.

I am going to try your potting mix, and make sure that wicking is happening.

Thanks, Al

Bob

Al: If there's a possibility of salt buildup and the gardener doesn't wish to switch out the potting mix, wouldn't you recommend a single, sustained leaching with clear water to run the salts out of the bottom of the container, after which you resume your normal winter watering regime? I'd think you'd want to do that just prior to taking the plants outside in the Spring (at the very latest).

Thanks for the kind words, Bob. Good luck this year!!!

Steve - yes, absolutely. I get lots of mail this time of year from folks with plants exhibiting tip-burn and dry/necrotic leaf margins. Almost universally, they attribute the malady wholly to low humidity levels in the home, but as you note, there is more at work.

Growing in a soil that requires you to water in small 'sips' to prevent saturated soil conditions and accompanying root rot, instead of watering so that the soil is flushed at every water, promotes the accumulation of both fertilizer and irrigation water salts in the soil. There is an inverse relationship between accumulating dissolved solids (salts) in soils and the plant's ability to absorb water (and the nutrients dissolved in the water). As the level of salts increases, the plants ability to take up water decreases. Plasmolysis (fertilizer burn) to varying degrees is the extreme result, and can occur even if you are not applying fertilizers.

As Steve pointed out (if you can't/don't want to grow in a fast medium that allows you to flush the soil at each watering) flushing the soil intermittently is a good remedy. I think around a month would be a reasonable interval between flushing operations and to insure minimal accumulation of salts, flushing soils regularly should continue for as long as you're forced to water in sips.

This is a very effective way to flush soils and still minimize the chance of root rot:

Completely saturate the soil and allow it to drain. In succession, and at about 15 minute intervals, pour approximately the same volume of water the plant's container would hold through the soil. Do this 3 or 4 times and it will remove a huge % of the salt accumulation. To help remove any extra water in the soil, you can unpot the plant & set it on a newspaper overnight (or as long as you feel it reasonable - o/a soil mass will determine what is prudent). The newspaper will pull water from the soil and it will evaporate. You can undertake this whole procedure in the shower & wash foliage at the same time for added benefit. If you do not wish to unpot the plant, you can push a wick through the drain hole, up into the soil & allow it to dangle below the container. This will also remove a high % of water the soil might 'try' to retain.

Thanks, Steve - and thank you again for the recent link. I enjoyed the read. ;o)

Al





This message was edited Feb 27, 2008 8:56 PM

A grower I know in Michigan who grows geraniums from unrooted cuttings told me that the plants hit a "wall" about every 30 days when they're being fed with water soluble fertilizer in the irrigation process. Leaching salts is necessary to keep the plants on track, and about once a month is a good time frame. Even growers who are very careful about the rate at which they feed eventually have to deal with salt buildup to one degree or another. Of course, one of the biggest problems greenhouse growers have is to keep the resulting leachate from entering the water table, and none of the solutions are easy or cheap.

Hi all:

Recently I built 3 really raised beds. Each is 8'x2'x 15" or so deep. From this thread I figured that the size of the "container" might have an effect on the makeup pf the mix.

I am planning on a veggie garden.

Al... does your formula need to be adjusted for "containers" of the size that I have????

Thanx

Laska1

This message was edited Mar 16, 2008 9:18 AM

Al,

What are "pine bark fines". Here in New York I can't find anything like this. The only products that I see here are either "pine bakk mulch" ( some of it is dyed red or black) and pine bark nuggets.

Also I have read about "cocunut husk chips" that seem to have some good qualities. Can these be substituted for "fines" and if yes any idea where they can be purchased in bulk. All I seem to be able to find are small bags aimed at orchis growers.

Please help.
Thanx

Laska1

This message was edited Mar 16, 2008 9:21 AM

This message was edited Mar 16, 2008 9:23 AM

. . . does your formula need to be adjusted for "containers" of the size that I have?

No it doesn't, as long as the containers are elevated like yours. If those containers were on the ground, they would simply be raised beds, and because of the wicking effect of the soil below the beds, you could grow very successfully in a much finer soil.

Pine bark fines are finely processed pine bark - usually partially composted. I prefer this for my garden display containers & veggies - anything I intend to last for only a year, though it would probably be structurally fine for a second consecutive growth cycle. You can see an example of it at the top of the image I'm posting. I'll post another image of other bark just below this post. I can't figure out how to post more than one image in a post. If anyone knows how, I would appreciate a heads-up and some instruction?

Al

I have tried side by side comparisons of cuttings from the same plant - one grown in the mix I usually use, the other was the same mix, except that I substituted CHCs for the bark. I leached the CHCs very thoroughly to remove any soluble salts, and I even used gypsum instead of dolomitic lime to help keep the pH south of neutral (CHCs are pretty neutral in pH, so when you add dolomitic lime as a Ca/Mg source, it pushes the pH above 7, which starts to affect the uptake of many nutrients) and added Epsom salts to the fertilizer water to be sure they were getting Mg. I was careful to water on an 'as needed' basis, instead of a schedule. I just found that the CHC's did not allow any where near the same increase in bio-mass (growth) that the plants in the bark mix did. Others may relate entirely different experience, but having tried the comparison with multiple genera of plants, I think I'll stick with the conifer bark. There is also the expense factor, with bark being much less expensive. Those two reasons alone, clinch the decision for me.

Here is the second pic of bark products I promised. Notice that none of it is dyed? At the top, is screened fir bark I buy in 4 cu ft bags for around $20. I only use that in my bonsai or houseplant soils. The other three pics around the perimeter are all southern yellow pine bark that came from different places. One came from Meijer, one from Home Depot, the other from a nursery just down the road a mile or so from my home. Any of these barks would also work extremely well in a soil for your containers. As you can see, the product is out there, and in my opinion, it really is worth searching for. It may be bagged and called, soil conditioner, pine bark mulch, premium landscape pine bark mulch . . . or any one of a number of other names.

Good luck, Laska.

Al

Hi Al,

You have to put the two photos together from your photo editing software. Here's instructions for Paint Shop Pro, if you happen to have that. I'm sure all the rest of the software products have their own way of doing it. http://www.xeramtheum.com/Gourd3.htm

By the way, I wicked my potting soil as you suggested last fall, and the bulbs are coming up this spring. Of course, muscari is just a start, but I'm expecting all of them to bloom in my containers. Great advice you gave me.

I meant to post a pic, so here it is. I keep forgetting to trim off the wick at the top in one of the pots. I have two other large pots where I used Al's method of wicking.

What did you use for wick?

Shoelaces. DH made me promise that if he needs shoelaces I have to buy them for him. (I stole his. lol)