A Discussion about Houseplant Soils (long post)

A SOIL DISCUSSION

I have been thinking about what I want to say about houseplant soils here, and how I should open. I’m going to talk a little about soils, primarily from the perspective of what is best for the plant - not the planter. ;o) More often than not, the two ideas are mutually exclusive, and the plant suffers loss of vitality for the sake of grower convenience - even if unknowingly. There is absolutely nothing wrong with that. Probably none of us can afford the time it would take to give our plants the very best care possible, and we need to decide on an individual basis how much attention we can pay our plants. I’ll explain later, but hope to leave you with enough insight so that, at at a minimum, you understand there are options and alternatives to using commercially prepared houseplant soils.

Let me start by saying that whenever I say ’plants’ I mean a very high % of house plants and freely allow that there are exceptions to every rule; but, we need to learn some rules before we can recognize the exception. I’m going to offer a few (of what I think are) rules I believe are difficult to challenge, and that I have adopted in my growing practices after a fair amount of study and consideration. I’m going to leave light levels out of this conversation after acknowledging that they are probably just as important as soil to a planting, the difference being, we can recognize and change poor light levels easily if we choose, but poor soils are not so easily remedied.

Rule: Plants need air in the root zone as much as they need light and water. The soils we usually buy in a bag either do not supply enough aeration from the outset, or they do not supply it for a long enough period. Most, or at least many readers are expecting their plants to live in the same soil for several years, when the fact is that most peat based soils substantially collapse within a single growth cycle. That is to say that the peat particles break down into continually smaller pieces. This reduces the number of macropores (large air pockets), causes compaction, and increases the amount of water the soil holds in root zone and increases the length of time it remains there. Use of materials like compost, worm castings, or fine sand have the same effect.

What does this mean to our plants? Well, there is the specter of root rot, but even if we set that aside, there is something more subtle occurring. Whenever roots are deprived of oxygen (O2) they soon begin to die - incrementally. First, and after only a few hours in saturated, anaerobic (lacking O2) conditions, the finest roots that absorb water and nutrients begin to die. Already, the plant would be operating under stress. Gradually, thicker roots die unless the plant uses the water in the root zone or it evaporates and O2 is allowed back into the soil. When adequate aeration is restored, the plant will have been disadvantaged, because fine rootage has died. The plant begins to regenerate the lost roots, but guess what? It has to call on energy reserves it has stored because the roots cannot efficiently take up water and the building blocks from which it makes food (nutrients/fertilizer). This stored photosynthate that goes to root regeneration would have been used to increase biomass - flowers, fruit, foliage, stem thickness. See how subtly aeration affects growth?

Rule: Our number one priority when establishing a planting should be to choose a soil that guarantees adequate aeration for the expected life of that planting. We can easily change every other cultural influence if we choose. Light, temperature, nutrients, moisture levels ….. all can be changed, but we cannot change aeration, so we really need to consider that as a priority.

It is in our choice of soils where we need to bring attention to the fact that, as alluded to above, convenience has costs. I’m not saying that in chiding fashion. I simply want to make the point that when you’re able to go several days to a week without watering, in a high % of cases, the cyclic death and regeneration of roots is taking place. The plant is growing under stress and is weakened to varying degrees, depending on the severity of O2 deprivation in the root zone.

Rule: A fast soil that drains freely will be far superior from a plant vitality perspective than a more convenient soil that stays wet. The cost: You’ll need to decide if you’re willing to water and fertilize more frequently to secure the added vitality.

I could go on for days about soil, but I’m hoping that I’ll be able to discuss HOW we can get to a better place with regard to our soils through answering any questions that might come up, and exploring options. Before I close, I would like to talk for a minute about another bane of poor soils.

Many of us recognize what we consider the main danger of over-watering - root rot, and do our best to prevent it. Most often, we try to prevent it by watering sparingly, in small sips, so the soil is never saturated, but let me explain what happens when we do this.

Plants best take up water and the ions dissolved in it when the ion level is very low. This ion level is measured by either electrical conductivity (EC) or the total amount of dissolved solids (TDS). Problems arise when the TDS/EC level is too low, even when the plant can take up water easily. It easily remains hydrated, but starves for nutrients because there is not a high enough concentration of ions in the soil water. If the level of TDS/EC is too high, the process of osmosis is affected, and the plant cannot efficiently take up either water OR nutrients, so the plant can starve or die of thirst in a sea of plenty. It’s up to us to supply the right mix of all the nutrients in a favorable range of TDS/EC.

I’m sorry if I got a little technical, but I’m getting to a point. When using soils that are not fast enough (free draining) to allow us to water copiously and continually flush the salts that accumulate from fertilizer and irrigation water something unwanted occurs. Salts and dissolved solids from fertilizers and irrigation water will continue to accumulate. This pushes up the level of TDS/EC and makes it increasingly difficult for the plant to take up water and nutrients.

Imagine: A soil that is killing our most efficient roots (the finest are the first to succumb), which stresses the plant and makes it more difficult to take up water due to the lack of those roots, while it insures that the level of TDS/EC will rise, making it difficult or impossible on yet another front for the plant to take up water and nutrients. Is it any wonder that our plants start to struggle so mightily toward winter’s end? Are we really seeing the effects of low humidity or do you think it might be drought stress brought on by either an inappropriate soil and less than favorable watering practices? Probably a little or a lot of both.

Rule: Whenever you consider a plant in trouble, you must consider not only the plant, but the rest of the planting as well - including the soil. The insect infestations, diseases, and stress/strain we so often need help with here on the forum can almost always be traced back to weakening of the organism due to an inappropriate soil (or, as noted, inadequate light - though in an extremely high % of cases, it is indeed the soil).

This only touches on the cause/effect relationship of the soil to the planting. If there are questions, I’ll try to answer them. If there is disagreement on a point or points, I’ll offer the science behind my thinking and you can decide individually if the things I set down make sense.

I would strongly urge anyone who was not long ago bored to tears to follow this link to another thread I offered on the container gardening forum. If you would like to get into the science and physics of how water behaves in container plantings, this will help explain it: http://davesgarden.com/community/forums/t/719569/ It's likely you would come away with additional knowledge of what makes a good houseplant soil.

I hope this starts a lively discussion and provokes plenty of questions, but more importantly, I hope it eventually, as the thread progresses, helps put a few more pieces of the puzzle together for at least a few forum participants. ;o)

Al Fassezke

I know what you are saying, yet it is impossible, here anyways, to find a decent pre-packaged soil. They all seem to turn to cement after about a week. Do you have any favourite mixes?

I've been using my AV mix, half soil half perlite or vermiculite.

I read some of a previous soil discussion and saved a soil recipe of yours, Al. Would this be a good place to re post it?
That thread and this were very enlightening to me. Thanks.

My intent in starting this thread was to let you know you needn't depend on a bagged soil for your plants. You can do much better by mixing your own soils, and in the long run, if you purchase larger bags of ingredients, the cost for a premium soil will be less than what you pay for the bagged media most of you are using.

I grow virtually all my houseplants, including cacti and succulents in a very coarse mix of equal portions by volume, of a baked clay granule called Turface, crushed granite (chicken or turkey grit), and either pine or fir bark. The mix will retain its structure, guaranteeing excellent aeration, and stability long after peat and even bark based soils have collapsed.

I so often say that it's not too important what soils are made from, as long as they retain the right proportions of air and water for the life of the planting. The soil you see below will do that. Because it drains freely, you need to water and fertilize more frequently, so you need to decide if you're willing to trade convenience for considerable improvement in vitality.

This particular soil is my basic mix for houseplants. I've grown in it for more than 10 years, and I can attest to the fact that it is far superior to any bagged soil I've ever used. I'm not trying to sell you on "my mix" or any particular mix of ingredients. I'm trying to sell you on aeration and stability - two things you do not get from a bagged soil.

1 part pine or fir bark (appropriate size)
1 part Turface (baked clay granules)
1 part crushed granite (chicken or turkey grit)
gypsum
controlled release fertilizer (if the season is appropriate)

I hope there are lots of questions or comments.

Al

Very interesting thread Al ... I am printing it out to have available to re-read for the future! I don't retain much in this ole' brain of mine so I like being able to re-read info like this! And, if i don't print it out, I know I would never find this thread again!

I know I can buy pine bark from Home Depot and Lowes but where would I find the Turface? And, I will have to call around about the chicken grit too!

In the past I would mix store bought potting soil with bark and sand. Now I tend to mix the soil with the pre-packaged orchid mix which has bark, charcoal and perlite in it, which lightens it up.

You seem to know a lot about soil, so I wonder if maybe you could figure out what this lady has growing in her houseplant soil. I know I have bought bagged potting soil before that has all kinds of junk in it but have no idea what this stringy stuff is that this lady is finding in her soil. I'm assuming it is just some harmless plant material that has sprouted naturally in the soil but really don't have a clue. Maybe you would be able to help her with some suggestions.

http://davesgarden.com/community/forums/t/794622/#post_4260272

I'd like to stay focused on houseplant soils, but the photo you linked to, if they are not roots, are likely rhizomorphs (it means 'root forms') of some fungi, perhaps Armillaria cords, but I'm unsure of the exact binomial name.

I'm not sure if you'll find crushed granite in FL. I generally find that the near-coastal states use some form of crushed shellfish shells for grit, and that would be inappropriate. You could use VERY coarse swimming pool filter sand though. It comes prescreened and should be at least 1/2 BB size or larger. Finer sand does promote drainage in soils, but it also clogs macropores & robs aeration, so I never use it. If you're serious about making/trying the soil in the picture, I'll make a call or two for you. I have connections in the bonsai community in Daytona & I could scout up what's available.

Remember - it's not important what we use in the soil, as long as it's not poison to plants & it holds the right mix of air & water. One substitute for Turface is Haydite. Another is a product called 'Play Ball', so if you really want to go through a little searching for the ingredients (all rather inexpensive), you can build a soil that serves so well you'll never wish to go back to a peat-based soil again. I know I never will. ;o)

Here is the approximate size of pine bark you should look for (in the photo below). In the middle, is another soil that you can use that will outlast a peat-based soils several times over. It will initially perform as well as the gritty mix in the picture upthread, but will not last as long. Still, it will last up to three years in many cases, where peat soils have already begun to collapse badly before a year is out.

Good luck.

Al

Here is the recipe for the soil in the center of the picture above. It is an excellent houseplant soil and maintains good aeration for a long time - much longer than peat-based soils. As mentioned above, it is not as stable as the more gritty mix, but the ingredients are usually very easy to come by:

3 gallons pine bark (see picture above for appropriate size)
1/2 gallon peat (sphagnum peat please - no reed, sedge, or Michigan peat)
1/2 gallon perlite
4 tbsp lime or gypsum (ask about this if you make this soil)
1/4 cup CRF (if the season is appropriate - ask if you're interested in an explanation)
1 tbsp micro-nutrient powder (or make sure the fertilizer you use contains the minor elements)

Al


This message was edited Jul 4, 2010 7:09 PM

Well, you saved me money because next time I need soil I will be buying mostly pine for $4 a big bag instead of "mix" for $12 or whatever. I have had plants fail and now it all makes sense. So, now my plants are in for winter and some are in collapsed soil. Can I repot in this time of year, or would that be stressful? Should it wait for spring if possible.?

Do you ever use water holding crystals?

Hi, Sally. It's probably not best to repot until the light gets better & plants begin to grow in earnest, but you can help them out a little. If your soil is 'collapsed', retains lots of water, and drains slowly, you are probably watering in small sips, which causes salts to build up in soils. When this happens, the plants cannot absorb water or nutrients (ok - it becomes increasingly difficult for them to do so). ;o) At least once each month, you should thoroughly flush the soil several times with room temperature water. IF you know you have a problem soil and that it will not drain well for you, or if you're concerned about root rot, there a couple of things you can do to help drain excess water from the soil by employing some simple physics.

Easiest and very effective is a wick. Insert it through the drain hole and leave it dangle an inch or two below the pot after watering. This 'fools' the water into thinking the pot is deeper & it travels down the wick and drips off the end, effectively removing the saturated layer of water at the pot bottom.

Nesting the pot inside another pot with soil in the bottom does the same thing. Water moves downward into the soil in the lower pot, leaving the primary container free of saturation and improving aeration in the main pot immediately after watering.

Tilting the container after watering also causes additional water to drain. To confirm, water thoroughly & wait for the container to stop draining. Tip container at a 45* angle & you'll notice substantial additional drainage.

Also, if you hold the container at chest level and lower it at medium speed to waist level, then lift the container quickly back to chest height, you can use the physics of inertia of motion to help drain the container, too. Repeat until no additional water drains.

It is very important to return the soil to a well aerated state as quickly as possible after watering. It can make a huge difference in sustaining o/a energy levels and maintaining plants at maximum vitality within the limiting parameters of all other cultural conditions.

In spite of the mantra you read and hear repeated over and over, plants SHOULD be fertilized in winter - especially after leaching the soil as described above. Soils should be open enough to allow generous watering at every watering and a weak fertilizer solution, so that the right mix of nutrients are ALWAYS available in the 'adequacy' range, should be applied at regular intervals. If I might use an analogy that's easy to understand: Children grow in spurts, just like plants do. Just because we see that children's growth has slowed or seems to have stopped, do we withhold nutrients and vitamins? Of course not. Why then, during periods of slowed growth would anyone ever believe we should withhold nutrients from plants? I know the answer to that question, and it has to do with soil. Anyone want to see if they know the answer? ;o)

Al

Thank you Al for all this great information! I so totally agree about feeding plants year round! I never have understood why some folks say you should stop feeding in winter. I know a lot of plants slow down in winter but I've always felt it's still good to feed them - maybe not a full strength as you would during the summer growing season but it never did make sense to me to stop totally. I love the analogy of comparing plants to children ... makes perfect sense!

I'll guess and hope I'm not too stupid : ^P
The plants grow slower, so people watered with fertilizer, but not enough to flush salts, so the salts built up faster and hurt the plants.

Plants almost are our kids. See me dragging them outside on nice days in the winter for a little fresh air?

I stopped buying bagged soils a long time ago. I use leaf mould from the various piles of autumn foliage I save. It is coarse enough to provide good aeration, although I add a quantity of perlite to it for certain plants. My African-violets like a mix that is half leaf mould and half perlite. My pelargoniums thrive in equal parts leafs mould, perlite and garden soil.

I'm curious, Al, what your thoughts are about leaf mould.

I'm glad you found a mix you're happy with WG, but I am very cautious about adding organics that break down quickly to any of my soils, and I'm afraid that I would have to say that leaf mould is on the list of things I never use. I also shy away from garden or topsoils because they are really hard on aeration and tend to compact so readily and firmly when used in any appreciable volume. Whenever there is a more durable alternative to a possible component, I'll choose it nearly every time. In this case, pine or fir bark is an inexpensive alternative that improves aeration and will retain it's structure far longer than leaf mould. Turface and/or crushed granite would be my choice as an alternative mineral component.

Please don't misunderstand - I'm not saying you shouldn't use it, only that I wouldn't.

Al

I saw where Sallyg asked about something called "Water Holding" Crystals. What exactly is that? I've never heard of such a thing. I wouldn't use them because I don't want my soil to hold water, but I'm curious about what they are made of? Is it something that eventually breaks down in the soil? Are they safe for the environment?

There are a couple different kinds--there's one that's basically granules of superabsorbant polymer, it's the same stuff that's used in baby diapers to absorb the liquid. There's another one I think that's made from cornstarch which works similarly but is supposed to be more biodegradable and environmentally friendly than the SAP.

Thanks ecrane3! hmmm ... made from stuff used in disposable diapers huh? Those things take forever to break down in landfills from what I have heard! I just can't imagine using anything like that in my plants. Even if it isn't detrimental in any way, it just doesn't sound natural to me. I remember the days of cloth diapers and even though it was a real job to have to deal with them, it sure was better than all the plastic lined disposables that are sitting in landfills nowadays. I guess we have become a "convenient" society ... in more ways than one. Don't get me wrong, I love convenience, but sometimes I think we have gone overboard with trying to make things easier.

I'm not sure how much the water absorbing polymer contributes to how slowly diapers break down--I think there are other things that play a bigger role in that! But I don't imagine the polymer breaks down all that quickly. If you're worried about the environmental impact but you want the water holding benefit, the cornstarch based ones are the way to go--I think the brand is Zeba or Ziba or something along those lines. But I might be remembering the name wrong--I don't use them (it's way too easy to overwater things, without have water holding crystals to help me out!)

Nope, I don't need them either. I don't want to end up with my plants holding too much water and rotting! I was just curious about them since I had never heard of such a thing!

I think my houseplants are really nice and all I ever use is a mix of Sunshine #1 mixed with perlite and vermiculite.....I also fertilize often with a balanced fertilizer.(unless it blooms and then I use a 12-36-14 fertilizer)

I don't think I am smart enough to try Al's mix although it makes good sense.

Ohhhhh Gessiegail - You sell yourself way too short! Of course you can do it if you wish. There are lots of people in TX using Turface in their mix. If you REALLY want to - I'll help you.

Can I make a fertilizer change suggestion? I think you'll be much happier with either a 24-8-16 or a 12-4-8 liquid blend with micronutrients - even for the blooming plants. If you wish, I'll explain why the high P formulas are not as effective as people think and they often have up to 20 times more P than the plant can ever use. These formulas induce blooms through stress, but there's a better way. ;o)

Al

I will agree with you on that fertilizer I picked up in Boerne, Texas. I have already changed my reservoirs of the gesneriad family because they were being forced into bloom and still were tiny babies.

Can you tell me who makes these fertilizers? let me tell you the ones I takes turns using now (just in the past 3 weeks did I start rotating fertilizers). Schultz 10-15-10, Otpimara 7-9-5, Optimara Plant Food 20-5-10, the 12-36-14 and Eleanor's V11.
thanks
gail

Look carefully at the chart I made. It shows the range of nutrients found in almost all plant's tissues. 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
K 45-80
S 6-9
Mg 5-15
Ca 5-15
Fe 0.7
Mn 0.4
B(oron) 0.2
Zn 0.06
Cu 0.03
Cl 0.03
M(olybden) 0.003

You can see that plants use about 6-7 times more N than P. The rest of the P is wasted or acts as a stress agent. Simply reducing your N applications is more effective and better for plants than a high P blend. Reducing N slows vegetative growth, while allowing photosynthesis to continue w/o interruption. Since the plant is not making leaves or extending branches, it has plenty of reserve energy to put into blooms and fruit.

What’s the harm in a little extra P? Well it’s more like 10-20 times the amount needed in some formulas. Even formulas like 20-20-20 and 14-14-14 have much more P than required for healthy growth. Excess P can immobilize some trace elements, as well as forming insoluble compounds with calcium.

When commercial operations fertilize, they often use sophisticated tissue analysis to determine which of these 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 10:1.6:6.3 noted above.

I would like you to take note of how close that ratio is to a 3:1:2 ratio and that in comparison, the N level is actually comparatively LOWER in a 3:1:2 than it is in the 10:1.6:6.3 ratio found in plants. In truth, and I've already mentioned this, most greenhouse operations, because there is intentional manipulation in the young plants will start at something closer to a 2:1:2 ratio and finish with something closer to the 10:1.6:6.3 (or close to 3:1:2). Nursery plants will be fertilized fairly close to the 3:1:2 ratio as well. For clarity, finished means when the plants are ready to be hardened off & offered for sale.

Remember that we struck an average for the range of nutrients in tissues. I made no claim that all plants will have the same levels of nutrients present in tissues. If you examine the range though, you will see that moving to either extreme of the range does not significantly change the ratio - certainly not more than one point.

Some of us are fairly good at discerning symptoms of simple nutrient deficiencies, but you need to be a good detective and have a clear understanding of macro/micronutrient relationships to be even halfway accurate. Since none of us likely has the ability to analyze tissue & correct deficiencies by fine tuning our fertilizer program to the nth degree, we need to make an educated guess at at the best shotgun approach.

24-8-16 and 12-4-8 are both fertilizers in the 3:1:2 ratio. The 24-8-16 is even available from more than one supplier with all the minor elements included. This blend is often called an 'all-purpose' fertilizer for good reason, and has been around forever. It has about the closest ratio of major nutrients to what plants actually use.

These are all fertilizers in a 3-1-2 NPK ratio:
Miracle-Gro 24-8-16 w/micronutrients Click on 'view label' for analysis
http://www.miraclegro.com/index.cfm/event/ProductGuide.product/documentId/637153cfaa6b1ff545c0236933b0a7a4

Schultz All-Purpose 24-8-16 w/micronutrients Scroll down the page for analysis.
http://www.drugstore.com/qxp81902_333181_sespider/schultz/all_purpose_plant_food.htm

Peter's (Scott's) 24-8-16 w/micronutrients Scroll down the page for analysis.
http://www.scottsprohort.com/_documents/WSF/PetersProfessional/H4071.pdf

Miracle-Gro liquid 12-4-8 w/micronutrients Click on 'view label' for analysis. This is what I use for 90% of all my plantings.
http://www.scottscanada.ca/index.cfm/event/ProductGuide.product/documentId/8AA325CB3201B064850BAC15135A32E0

All the above are readily available at nurseries or big box stores. I doubt any of us could tell any difference between their performance. You'll note that only one supplies any Mg (@ 1/60 the rate of N) and none supply Ca. That is because container soils are usually pH adjusted with dolomitic lime, which supplies both Ca and Mg in a favorable ratio. If you are making your own soil, you'll need to add a little dolomitic (garden) lime or gypsum (both very easy to come by and very inexpensive).

Adequate amounts of S are supplied in the ammonium and zinc sulfate vehicles that supply N and Zn.

... that cover it? ;o)

Al

Remember - it's easier than it sounds & I'll help you out!


This message was edited Dec 15, 2007 12:22 PM

This message was edited Dec 15, 2007 12:27 PM

This message was edited Dec 18, 2007 6:07 PM

ok, now my head is swimming...

:)))

My head is SPINNING! Wow! Al, are you a Scientist, Biologist? I can tell you are very intelligent but all this soil and fertilizer stuff is way over my head too!

When I remember to feed my plants, I have been rotating between Dyna Grow Liquid 7-9-5 and Eleanor's VF-11 Liquid 0.15 - 0.85 - 0.55 for about a year now and not knowing it might be stressful for my plants. I guess I never even thought about it one way or the other. We buy what someone states is good to use, or what another seems to be having success with, not really taking the ingredients or concentration of what's in those ingredients into consideration. Which, I guess means we are not considering the health and well being of our plants.

I think I will go buy some Miracle Grow Liquid 12-4-8!

Thanks Al for trying to help us by instructing us on all this technical stuff!

It's NOT over your head. ;o) Ask whatever specific questions you want about soil or fertilizer & I'll answer in as 'easy to understand' terms as I can (that is, if I know the answer). I really AM capable of making it easy enough to understand, so you know WHY I suggest something. I'm only here because I love to think I'm helping. I don't really care about 'attaboys' or attention, but a thank you (yours & others) is always very pleasing to the ear. ;o) When you ask questions, everyone that reads the answer gains an opportunity to learn. I learn plenty here from the things you ask too. If I don't know the answer, or if I need to confirm what I'm saying is accurate, I go look it up. Invariably, while I'm confirming things, I learn something new. Experience is a wonderful thing, but it's knowledge that will set you free. ;o)

Al

Rather than trying to figure this out, I am going to trust you as you sound very knowledgeable I really appreciate your making a list of the ones that fit the 3-1-2.
I am quite sure i stress my plants out big time or they wouldn't be blooming when they are tiny babies grown from leaves. That isn't even the natural cycle of things.

Thanks again

Oooohhhh Nooooo! I WANT you to try to figure out the big picture! ;o) Don't give up! Ask questions - learn about soils. That's where the foundation of ALL your plantings is - in the soil. Once you get that down, it's ALL downhill from there.

If I had someone that was willing to teach me things I don't know about plants, you can bet I'd be taking advantage of it. What if I beg? ..... Please???

Al

I have a bag of somebody's Bloom mix,10-20-10 or something like that. It did force a lot of bloom on my Lantana, but then it stopped, like all the buds went at once.
Is there an easy way to get some nitrogen so I can use a little of this Bloom mix and up my nitrogen?

tapla,
Ok, you win me over, but you have to wait until after Christmas and keep this discussion going. I am too far behind to settle down and even think.....You are too nice to put up with us!
gail

Sally - it won't break the budget to buy a quart of one of the liquid fertilizers with micronutrients I linked to about 10 posts upthread. They are very inexpensive. I think I paid about $5 each for the last 6 quarts I bought. 10-20-10 would have about 34 times more Phosphorous than a plant can use, so imagine how much the 10-52-10 formulas will have - more than 88 times what's needed!

I doctor my fertilizers by adding some hard to get ingredients to them in concentrated form, and then diluting as needed, But basically, I use a 3-1-2 ratio (which is sometimes a 24-8-16 actual blend, but more often I just use the 12-4-8 Miracle-Gro with micronutrients) on almost all of the 250-300 containerized plants I grow, both indoors and out. It works better than anything I've used yet.

Gessie G - I'll watch for you later then, but it's up to you guys to keep the thread going. I'll be here as long as we stay focused on soils or fertilizer & stuff. ;o)

*****************************************************************************************************
Sometimes threads deteriorate into back & forth chatter that has nothing to do with the subject. I hope that this thread can stay focused on soils and related issues so future readers don't have to sift through a lot of impertinent data to get to the info. I hope that sounds like a fair request to you guys. ;o)

Al

Al, I promise I want to learn and understand. I just know bits and pieces like using epsom salts in some plants because I was told that the magnesium gets tied up in the soil and is not available for plant use???????

But if the thread is not still going after Christmas, i will find it and bleed you dry of your knowledge *lol*

Al,
I will be willing to go find whatever you say to make my own soil. The biggest problem I have (and I have 8 gro lights stands plus plants all over my house) is that I wick everything and I can't seem to find the right mix and the right size wick to keep the plants dry enough.

That means I spend a lot of time walking around taking wicks out for the day and then remembering the next day to put them back. I also have a confession to make: I have started using 1/4 tsp Marathon per pot to keep the mealy bugs from not forming and staying in the soil. I normally repot every 3-4 months anyway. (the gesneriad family)

I am dead serious about growing houseplants and I think I do understand what you mean about the roots being able to get enough air to stay healthy. I just don't know how to accomplish this.

If I sent you pictures through dmail, would you be able to tell by looking what you think my plants in general look like compared to what you would expect from your houseplants?

When you started this new thread, I cleaned out the perma nest trays and every reservoir in the house (hard work) and am using very light fertilizer right now. It may be my imagination but I really think the plants look happier already. (I know I was over fertilizing with too high amount of phosphorus)

I have read and reread your posts and really am willing to do whatever it takes to have beautiful gesneriads and other houseplants.
gail

I just read your post on the container forum. I think, if I am right, that all I would do to get a good soil would be to quit using the AFrican Violet soil-less mix and use Canadian peat in place of that 1 part, then the same 1 part perlite, and then add the Pine Bark.

But now I am confused because you have a different recipe on this thread on indoor gardening?

Gessiegail - don't believe what everyone tells you about adding Epsom salts to your irrigation water. There are 2 things to consider. First, plants only use an average of 1/10 the amount Mg as N. If you look at the chart

N 100
P 13-19
K 45-80
S 6-9
Mg 5-15
Ca 5-15
Fe 0.7
Mn 0.4
B(oron) 0.2
Zn 0.06
Cu 0.03
Cl 0.03
M(olybden) 0.003

and do the math, you can see that on the low side plants use about 1/20 the amount, and on the high side, they use about 1/7. The other thing to consider is this: there is an antagonistic relationship between Ca and Mg in soils. Too much of one, affects the uptake of the other. If you add Mg w/o adding CA, the excess Mg BLOCKS Ca uptake - not good at all, so be careful how you tinker unless you're sure of a Mg deficiency. ;o)

If you're using a prepared soil, it probably already has dolomitic lime added to adjust pH. It supplies both Ca and Mg in the proper proportions. If you're mixing your own soils, you probably need to add either dolomitic lime or gypsum as a Ca source (depending on what your soil is made of). If you use the dolomite, you needn't add any Mg (it's in it), but if you are adding gypsum as a Ca source you WILL need to supplement Mg with very light doses of Epsom salts when you fertilize. If you look at most soluble fertilizer labels, you'll see they don't contain either Ca or Mg.

Try to find pine or fir bark that looks like what's in the second pic from the top (of the thread), and some Turface MVP. Call Profile Corp 1.800.207.6457 and ask for the distributors nearest you. If the distributors won't sell to you direct, ask them who their customers are. I have several friends in TX who use it, so I know it's available with a little searching.

We need to talk about your wicking idea too. If you need to wick to extend intervals between watering, you MUST regularly leach (flush) the soil to eliminate accumulating salts from fertilizer and irrigation water. If you don't, it will raise the level of dissolved solids and electrical conductivity of the soil soo high, that plants will not be able to absorb water or nutrients - no matter how wet you keep the soil. They will drown/starve in a sea of plenty.

You can mail pics or post them here if you like. If it's easier, I'll just provide you my e-mail addy.

Al

GG - the container gardening thread is a soil to be used for growing annual display containers & veggies. It lasts about 2 years and you MIGHT be able to stretch it to 3 years. For comparison: Most peat based soils from a bag are already collapsing badly before the end of a single growth cycle (1 year). So, that recipe will work fine for houseplants, it just won't last as long as the gritty mix I provided above, which is what I grow all my houseplants in. The gritty mix will last far longer than any plant should be left in the same container. ;o) After all, it's 2/3 inert.

Tip: The gritty mix makes it VERY easy to bare-root and root prune at repot time, a practice I strongly support for a very high % of plants.

Ok.........then the mix you provide above will work for African violets and all its' cousins rather than what the AVSA magazine says. I trust you and am willing to try it.

I am just going to post a few pics to tell you the problems in soil I have with each one
This is a streptocarpus. i tried to wick them, but they tend to have crown rot and have to be planted perfectly. I have given up on the wicking with these although this one was wicked until I gave it away.

Now I just water from the bottom in permanest trays. I also have to make the mix lighter with perlite so they never stay wet.

I don't seem to have much of a problem with gesneriad and begonia seeds or the plants if I keep them dry enough. (I sow the seeds in the same mix I plant the african violets in)

Look how nice and full she was. My soil was wrong!!!!! I had to take her out of the pot which stayed too wet and now I am starting all over in a smaller pot with small root system. The principles you were talking about apply here. Her roots just started to rot. I am sick about it.

This is a chirita tamiana grown from seed. I am just realizing as I am posting pictures that big standard African Violets and the big big Chiritas (not like this one) I get frustrated as i can't find a soil that drains well enough and fast enough.

Question though. If I follow your recipe and use the right fertilizers do you think the problems I am having with drainage for the large african violets will be solved? Also, I have very alkaline water so do I still need to use lime or dolomite or whatever it is called.

This is Gloxinia sylvatica and here she looks nice and I worked so hard. I virtually killed her for lack of drainage over a 5 month period. Now she is coming back slowly and looks pathetic!