Jodik's questions on winter fertilization

farkee(Florida)January 18, 2011

A few days ago Jodik asked several questions concerning winter fertilization when Jane mentioned that fertilization be reduced over winter. Jane also mentioned the importance of light and the limitations of low light levels.

Several posters took issue with her suggestions So I thought I would repeat part of what I posted as I referenced several university sites. I wrote it in Word prior to posting as I didn't have time to look it up in one session. Edited version.

Jodik asks: "Who recommends withholding fertilizer over winter? Where does this recommendation come from? And why is it recommended? What are the factors involved? In what specific circumstances is this a valid recommendation?"

What Jane said concerning fertilization and light is very common advice.

Texas Aggie Extension:

"During the winter months no fertilizer need be added at all because reduced light and temperature result in reduced growth. Fertilizing at this time could be detrimental to some house plants. "

Also mentions light as most essential. SEE LINK.

Univ. Of Minnesota

"Plan to fertilize when plants grow actively, usually spring and summer's longer days. Then reduce or eliminate fertilization the rest of the year. Plants growing under fluorescent lights won't experience a seasonal change in light, so they might need fertilizer applications year-round. " Also:

"Light is the most limiting factor to good houseplant growth indoors"

Univ. Of Florida:

"No other environmental factor is more important in growing good plants indoors than adequate light."

also recommends reducing fertilization in winter

Univ. Of Missouri Extension Publication

"When to fertilize

Fertilizing once a month is adequate for most houseplants that are producing new growth or flowers. However, plants do not need fertilizer in winter when no new growth is apparent.

Do not use fertilizer to stimulate new growth on a plant located in poor growing conditions. Lack of growth is more often due to improper light or watering than to nutritional deficiencies. In such cases, adding fertilizer may actually cause additional injury.

Drop of lower leaves, overall yellow-green color or weak growth may indicate a need for fertilization. However, these same symptoms may result from poor light or overwatering, so evaluate all conditions before fertilizing more than normal."

People don't have to agree with everything they read in books or extension publication. For instance , potting mix suggestions are usually peat based with a few exceptions and few posters here have had success with such mixes.

However Jodik, particularly asks, who recommended

reducing fertilization over winter so thought I would link several sources whether you agree with the suggestions or not.

Here is a link that might be useful: Texas Univ /Aggie advice

Here is a link that might be useful: Texas/Aggie Suggestions

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greenman28 NorCal 7b/8a

Jodi's questions weren't a request for web-site information.

Although those sentences ask for a "Who," she was rhetorically asking
about the cultural conditions for which the recommendations were given.

In other words, the recommendation to reduce fertilization in winter usually comes from
those growing in slow, heavy, or peaty soils. Or, similarly, the advice is being given to
those who grow in slow, heavy, or peaty soils.

However, for those who grow in fast, light, soil-less mixes, the recommendations don't really apply.
Thus her questions - from Whose conditions is this information dispensed.

I think Jodi will clarify further, and I hope I haven't misinterpreted her intent.


    Bookmark   January 18, 2011 at 9:20PM
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Josh, I think you hit it right on the nail.

If I recall, no one ever disagreed with holding back on fertilizer in heavy, peaty mixes, but then I could be mistaken. In fact I think someone had suggested flushing the soil mix out as needed if they should do so.

I do remember the disadvantages of using heavier mixes in which the majority do, including many I know with lower light levels and in the winter, and thank God I do not have to face these issues anymore.

I am one of those that can and continues to defy those that suggest to hold back and my plants prove otherwise, even this month, in the dead of winter with just a few hours of light. I guess I am a minority?


    Bookmark   January 18, 2011 at 10:04PM
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tapla (mid-MI z5b-6a)

I explained this in detail again, as I have many times before. I have always been clear on the fact that those growing in heavy, water-retentive soils who CANNOT flush their soils regularly when watering are not candidates for continuing to fertilize during the winter. My words are being twisted into something I never said, and would never say, and then an argument made against the words put in my mouth. This is a very common tactic lately.

Those of us discussing fast draining soils know and understand through common sense and practical application that frequent fertilizing of these open soils at low doses while simultaneously flushing the soil allows growers taking advantage of these soils to keep fertility levels in the low adequacy range at all times while keeping nutrient ratios to each other at favorable levels, also at all times. This allows the lowest possible EC/TDS levels without nutrient deficiencies and ensures that soluble salt levels do not climb to levels that make the uptake of water and nutrients dissolved in water difficult for the plant. Does it get any better than that? Are nutritional deficiencies and toxicities, no control over EC/TDS, along with virtually ensured rising pH preferable?

This issue was/is being played as though I was suggesting everyone should fertilize all winter long, regardless of what type of soil was being used, which couldn't be farther from the reality of what I said. I have a thorough understanding of the importance of EC/TDS levels in soil and have been managing and helping people manage them in free-draining and well aerated soils, as well as in heavy, water-retentive soils for years.

If anyone has been lead to believe anything other than what I just described, they have been duped. There are dozens on dozens of threads in which I clearly explain why you CAN fertilize at every watering using soils like the 5:1:1 and gritty mixes (and I usually add "if you wish") and why you cannot follow this practice when using heavy soils.

I have too many containerized plants to fertilize at every watering in the summer, but in the winter I fertilize at EVERY watering (gritty mix) and have been doing so for going on 20 years, so to suggest you can't or shouldn't is to argue with reality. I offer the hundreds of pictures I've posted of plants with perfect foliage and color as exhibit 'A'. The point has always and forever been clearly granted that this approach is INAPPROPIRIATE with heavy, bagged soils.

I've ALWAYS flat out said that you cannot use this approach with water-retentive soils. It is very difficult to manage EC/TDS effectively, and pH induced nutrient issues are also extremely common when your only option is to sit and watch dissolved solids accumulate unless you regularly flush the soil.

If this practice of frequent fertilizing at low doses along with regularly flushing the soil did not/could not work, and wasn't extremely effective, hydroponics would be impossible. The fact is, it works much better and is far superior to simply sitting on our hands all winter and hoping nothing too bad happens to our plants as a result of elevated EC/TDS.

This is simply another straw man tactic, of which there have been many, and has no basis in anything I ever said.

Jodi asks "And why is it recommended? What are the factors involved? In what specific circumstances is this a valid recommendation?"

The answer to those questions is 'to protect people that don't have a clue about how to manage EC/TDS from themselves'. When there is a valid discussion by people who have moved beyond the need to have their hands held when it comes to managing their growing, it's very disruptive to have someone enter the discussion and intentionally turn every one's words around.

I think, Farkee, in all fairness to you, you're coming in on the tail end of a discussion that has been made to appear as something it isn't. I think you know me well enough and understand that I would not make the suggestions that have been implied. Jodi's questions were simply another attempt to reveal that the person responsible for yet another grousing match is following a pattern of intentionally instigating strife, or simply does not have enough understanding of the topic to be arguing with those that do. Unless she wants to openly discuss the logic or science, it cannot be any other way, but she won't/can't.


    Bookmark   January 18, 2011 at 10:41PM
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Exactly, Al...

I had wanted Jane to answer the questions, since she made the statement. She is the only one that can qualify her own statements.

Josh, Mike, Al... thank you. You guys got it.

After much research, and much learning, it comes to me that people who say that fertilization should stop in winter are generally influenced by the commercial markets and the information they've cultivated for decades... and are not taking scientific fact into account.

Many of my plants begin or continue growth during the winter months. Why would I want to stop feeding them? And even when I can't actually see growth with my naked eye, I know it's happening on a cellular level.

I qualify my statements with the fact that I use a fast draining, aerated, gritty medium that allows me to water and flush frequently.

You cannot accurately make a blanket statement about all containerized plantings... in many cases, that one statement won't fit.

    Bookmark   January 19, 2011 at 8:21AM
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Thank you Farkee for your informative links. The information speaks for itself.

Light is always the most important factor in growing a healthy plant.

I've never promoted one potting mix over another. Its not that important. I use a simple method of amending a commercial mix. It works for me. I like simplicity.

It doesn't matter to me what people use as a potting mix for their plants. If there isn't proper light it won't matter to the plant either.

Life is complicated enough. Thanks again for taking the time to include that information.


    Bookmark   January 19, 2011 at 3:48PM
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Light is the most important factoring when growing healthy plants ? Just wanted to make sure I quote that right.

Well maybe it comes in at a close second but in bio-science life terms where they included ALL living things. Water is the most important factor.

Althou I have no idea what light and water might mean to anyone trying to understand the information from the fertilizing information being emphasized on this thread Please excuse my interruption of an off fertilizing comment.

    Bookmark   January 19, 2011 at 5:16PM
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There's nothing complicated about continuing needed fertilization during the winter months. In fact, it couldn't be easier.

The linked information is not necessarily correct from a scientific standpoint. They are mostly blanket statements influenced by the commercial markets. Just because a piece of information appears on the internet, even from a university website, does not give it supreme credibility. Most of the information would not, and does not, apply to my own growing, therefore, it cannot be said to be accurate. Blanket statements seldom are, though.

I'm still waiting for Jane to validate her statements about light. What is it that makes light the most important factor in growing a containerized plant?

Wouldn't moisture, nutrition, support, the exchange of oxygen and gases to and from the roots, ambient temperature, humidity, container drainage, and every other factor involved in successfully growing a containerized plant play just as important a role as light?

Haven't we discussed Liebig's Law ad nauseum? For those that haven't been following along, Liebig's Law states that growth is controlled not by the total of resources available, but by the scarcest resource (limiting factor). It's a simplistic scientific idea.

Keeping that law in mind, if light is not the limiting factor, and water is, it wouldn't matter how much light you gave the plant; it would not grow. Therefore, light cannot be the MOST important factor in growing a containerized plant.

And so, I ask again... what is it exactly that makes light the MOST important factor in growing a containerized plant? Why aren't all the other factors involved just as important?

The very fact that we all grow different potted plants in different environments makes it impossible to make a statement such as Jane's without qualifying it by saying it's only her opinion, and not a fact.

    Bookmark   January 19, 2011 at 5:47PM
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tapla (mid-MI z5b-6a)

For anyone looking for an assessment of light's role in the growth of plants that can be reconciled with science, this thread about the multiple factors that have the potential to limit growth offers a reasonable perspective w/o sweeping statements regarding How Plant Growth is Limited.

Liebig's Law of the Minimum is taught in virtually every horticulture class, and provides a sound platform from which to view a host of factors as having the potential to be equally limiting insofar as growth and vitality are concerned. Saying light is always the most important factor in growing a healthy plant' is no different than saying 'gasoline is always the most important factor in ensuring that you arrive at your destination on time.' Sometimes it is true - sometimes it is not. Like light, gasoline takes it's place alongside other potentially limiting factors such as engine failure, unforeseen detours, flat tires, driver error. It is simply illogical to make such broad statements, and it has also proven time and again to be inflammatory.

Again, I would challenge Jane or anyone else, to explain exactly how light can "always be the most important factor in growing a healthy plant". Reading the link above and evaluating Liebig's Law, + simple logic will provide the assurance that at times light will be the most limiting factor, and at times it will not.

It's only fair to point out that Jane has introduced this issue, which has negatively affected the entire tone of dozens of threads, on more occasions than I can count. Again, she cannot support the statement and it serves only to inflame.


    Bookmark   January 19, 2011 at 5:53PM
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I didn't need someone/anyone to explain Jane to me I kind of fell responsible drawing attention to a now newer lighting concern. Having no intentions of debating a different subject of what is also vital to one degree or another.Light and was asking that readers and comments keep the focus on fertilizing methods as the thread was originated and intended to be for.

I wasn't looking forward to or expected a response from any one person regarding what is or isn't the most important thing to them in a plant growing environment as it would draw different ideas from people such as AIR SOILS PH NPK VALUES ect.. You know what I mean! The theorist type stuff that we don't want to sound like or be.

    Bookmark   January 19, 2011 at 7:02PM
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I must concur with your evaluation of the thread, Al, as unfortunate as it is to think about.

If it's a fertilization discussion that's wanted, then that's what we shall have. It's January, and I haven't stopped feeding my plants. The days grew shorter and the nights grew cold, but my plants didn't seem to know that they should stop growing.

I know that my plants require nutrition on a regular basis, whether I can see growth with my eyes, or not. To stop feeding them would be depriving them of that which they need.

Growth has not stopped. In many cases, it hasn't even slowed down. Many of my bulbs are putting on fresh, new leaves... and have been since before Christmas. Even my orchids are putting out new leaves and growths.

To my knowledge, the only plants that have halted growth are even now sleeping outside, dormant under a blanket of snow. But indoors... indoors is where the action is. And so, feeding shall continue as required.

    Bookmark   January 19, 2011 at 8:43PM
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tapla (mid-MI z5b-6a)

Let's take a close pragmatic look at this argument.

If the contention that it is always bad to fertilize plants during the winter, there must be a reason for it. I'm guessing the concern is that fertility levels (the levels of EC [electrical conductivity] and TDS [total dissolved solids]) will rise and make it difficult for the plants to absorb water and the nutrients dissolved in water. This is a valid concern for all those using water-retentive soils that cannot be watered copiously enough to flush accumulating salts from the soil without risking rotting the roots, so if you're using heavy soils - forget about fertilizing frequently - you're pretty much stuck with sitting out the winter and hoping for the best.

Before I get to the meat of the issue. Let me comment that the pages of the houseplant forum are filled with horror stories about plants in the throes of death, a good % of which can be directly related to the soil; but, for the sake of keeping this discussion on track, I'll recant the soil comment and say they're related to an accumulation of solubles in the soil, and/or over watering. Let me see now - these people are not fertilizing because all the books tell them not to, yet solubles are accumulating and killing plants anyway. Before we go any farther, light isn't going to save a plant that can't absorb water from the soil. So, this advice not to fertilize sounds good, but it doesn't seem to be working for many people. I'll grant that NOT fertilizing SLOWS the accumulation of solubles in the heavy soils, but it doesn't halt it or keep it stable.

So, using a heavy soil that you aren't flushing when you water allows solubles to accumulate whether or not you fertilize. pH is almost always driven upward, which assuredly causes micronutrient deficiencies; and because there is NO way to regulate the ratios of each nutrient to the others, antagonistic deficiencies are also a very real potential issue ...... and this is all supposed to be good.

Now, consider that the original conversation didn't even involve these heavy soils - the conversation originally was about the gritty mix. Someone twisted the conversation and made it sound as though someone was advocating fertilizing plants in heavy soils all winter long. The fact is, no one was advocating anything - only saying that it is an option if you choose.

I'll now take anyone following this thread back to the original discussion about the gritty mix and reemphasize the fact that you can fertilize at low doses at every watering, all winter long if you wish. I hope no one dares say it can't or shouldn't be done, because I've been doing it for years, and others on this forum are also doing it. The hundreds of pictures of my extremely healthy plants are enough proof, even if the scientific and logical facts are ignored.

The gritty mix drains VERY fast. As you water, you flush accumulating salts from the soil - EVERY time you water. If you are fertilizing at every watering, the old charge of fertilizer is replaced (not added to) with a fresh charge of fertilizer - a very low dose.

This practice:
*Ensures the level of EC/TDS is always very low - lower even than if you simply stopped fertilizing plants in heavy soils in Oct or Nov
*Ensures that the ratio of nutrients is at the lowest level it can be w/o a nutritional deficiency
*Prevents the upward creep in pH associated with the mineral build-up in soils from dissolved solids in tap water
*Keeps nutrient ratios in balance to prevent antagonistic deficiencies.

And all this is bad? Frequent fertilizing at low doses and flushing the soils at every watering keeps EC/TDS LOWER than simply halting fertilizing - so by the 'reasonable man' standard, which practice seems to be the best choice?

When you add to the discussion the fact that thousands of people have had wonderful success growing in fast draining and well-aerated soils, fertilizing frequently at low doses, it doesn't leave much room for sensible debate


    Bookmark   January 19, 2011 at 10:36PM
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The long and short of it is... you most certainly can continue a program of nutrition for your potted plants all year 'round... IF you have attended to the needs of the roots... and, IF you aren't following conventional commercial wisdom, which is designed to make the industry more money at the expense of your plants, not to mention your enjoyment.

    Bookmark   January 20, 2011 at 5:28AM
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