I've planted many of my container flowers in Schultz Plus Potting Mix, which is supposed to feed them (well?) for several months. How do i know when the nutrients are about to be exhausted?
The other plants are in several different media recipes (including the pine bark recipe from Tapla which I'm still struggling to put together) and probably need some feeding about now. Hwo do I know when a plant needs to be fed?
Is going by the N-P-K the best guide for choosing a fertilizer for container plants and is there one or two configurations that are best for at least most of my plants?
I'd like not to have to buy more ingredients. I already have on hand: Miracle-Grow (all-purpose ); Pennington All Purpose 6-10-10; Espona Tomato Tone 4-7-10; Schultz All Purpose Slow Release 16-12-12; and SuperPhosphate 0-46-0. The TomatoTone and TriplePhosphate are about two years old but an email response from the maker says that as long as it was stored dry, it's fine (true?).
I've got Dahlias (from seed), Zinneas, Hollyhocks, Strawflowers, Impatiens, (Echinacea (Coneflowers), and Nasturtiums. I also have a few cucumbers, Scarlet Runner Beans, Poblano peppers and herbs.
Thanks in advance for information and advice.
Michaelangelo, The Greenhouse Idiot
Fertilizing
How do i know when the nutrients are about to be exhausted? --- How do I know when a plant needs to be fed?
Watch the leaf color of the older leaves. When you detect a lighter green color or a chlorotic (yellow) tint, it's time to feed. This only holds true if your watering regimen is appropriate. Too much/too little water will also cause yellowing, even though there may still be adequate nutrient levels in the soil.
Something I'd written previously:
I get asked this question frequently, or some variation like: "I want to feed my plants the best - what's best & how often should I feed?". Most people queried, would look right past the question and hand you a box or direct you to the fertilizer section of a plant store for "plant food".
Actually, you cannot feed your plants. Food provides energy - fertilizer does not. Plants manufacture their own food during the process of photosynthesis when the pigment chlorophyll traps the energy of the sun in a molecule of carbon dioxide and water. The result of this miraculous reaction, without which the earth would be uninhabitable, is a molecule of glucose - sugar - a carbohydrate - photosynthate. The molecule acts just like a battery, storing energy from the sun that can be translocated to all living plant parts for immediate use, or stored in living cells - roots, leaves, and cambium for later use.
In order for a plant to make and use food efficiently, certain elements need to be available to the plant. In fertile garden soil, it is likely, even probable that that the nutrients will be available in a usable concentration. In container culture, it is a virtual certainty that we will have to accept the responsibility for providing nutrients in usable concentrations for the term of the planting if we are to expect plants to grow at or near their potential genetic vigor.
The three main elements or compounds that are needed for plant metabolism are nitrates, phosphates, and potassium (NPK), and they represent the bulk of ingredients in balanced fertilizers. We term these ingredients macro-nutrients, sometimes referred to as "the majors". Also included in the macro-nutrient category, but necessary in lower concentrations are magnesium, calcium and sulfur. Rounding out the list of nutrients needed to keep plants healthy are the micro-nutrients, or "the minors". These nutrients include iron, boron, zinc, copper, manganese, molybdenum, chlorine, cobalt, and nickel. Please note that some of the minor elements, or micro-nutrients are required in such minute amounts that deficiencies are rare in garden soils, but more common in container media. For that reason, it is good practice to insure that you use a fertilizer that is complete, including the minors. If the minor nutrients are not listed on the fertilizer package, and you’re unsure that your soil contains an adequate supply, an excellent way of providing the minors while furnishing major nutrients is to use a granular soluble or insoluble product (e.g, STEM or Micromax). Organic fish and/or seaweed emulsions as part of your supplementation program can also be effective, but here I'll concentrate on the major elements.
Now that we've have seen that fertilizer is not plant food, but a way of delivering some of the raw materials or building blocks that plants need to make their own food and keep their systems orderly, I'll briefly say that it is important that we insure the soils we use contain adequate/appropriate volumes of air and water so as to make nutrient uptake possible and efficient, but that is another subject I won't dwell on today.
You can probably use a schedule or timetable to fertilize plants & have them be reasonably happy, but I use a different approach. If you do choose to fertilize on a regular schedule, it makes no sense to continue to fertilize when plants are quiescent due to chill, heat, or other unfavorable cultural conditions, Under these conditions, you might extend the preset intervals. Plants need more nutrients when robust and actively growing and less when they are "coasting".
I use a two-pronged approach to my fertilizing. The first thing I do is note leaf color of older leaves. N is a very mobile nutrient in plants. When it is deficient, plants "rob" it from older leaves to use in the production of new vegetative growth. So, when I see a lightening of leaves toward a lighter green or yellow, especially older leaves, and I'm sure that other cultural conditions are what the plant requires for good vitality, it indicates to me a need for supplemental nutrients.
A simplification of how I fertilize is: I attempt to get a higher percentage of N to foliage plants or those that are being grown for a reason other than blooms or fruit. Highly nitrogenous fertilizers support the plant during the growth of leaves and foliage. For flowering/fruiting plants, the phosphatic portion of fertilizers aid flower/fruit production, so I'll usually include the intermittent use of a fertilizer with higher percentage of P. Potassic compounds (K) stimulate the growth of roots and are included in adequate percentage in all complete fertilizers I use.
I use both chemical and organic fertilizers. As noted, but worth repeating, I determine the need for fertilization by leaf color. When leaves lighten and fertilizer is needed, I mix a recommended full strength solution of 20-20-20 soluble granular fertilizer and add a full strength solution of 5-1-1 fish emulsion in the same mix. This mix, I'll apply to foliage plants & plantings that are not dependent on blooms for their beauty. This is pretty much my standard for these plantings. For blooming plants, I'll use the same 20-20-20 fertilizer with a 2-3-1 fish emulsion included - UNLESS leaf color is good. If leaf color is good - I'll substitute a bloom-inducing, soluble formulation like 10-52-10 or 15-30-15 and still use the 2-3-1 emulsion. In all cases, I'll apply these solutions to well-hydrated plants growing in moist or damp soil, thoroughly saturating the entire volume of soil in the container.
I prefer the reliability and immediate action of the chemical soluble fertilizers for results, but understand the wont of some to remain organic. Generally speaking, organic fertilizers do release nutrients over a fairly long period, but there is a potential and considerable drawback in depending solely on them. They may very well not release enough nutrients to give the plant what it needs, when it needs it for best vitality. Organic fertilizers depend on soil organisms to break them down into elements the plant can assimilate, so most of them are effective only when soil is moist and soil temperature is warm enough for the soil organisms to be active. This soil organism population is a boom/bust proposition in container soils due to the extreme variables of temperature, moisture and pH. Nutrients in chemical form are immediately available for plant use and exhibit no dependency on soil biotic activity for availability. Plants do not care whether their elemental building blocks are provided in chemical or organic form.
Additionally, practices that promote high population numbers of soil organisms that feed on organic particulates hastens soil structural collapse, which is certainly counter-productive to your need for an extended-life soil. When I think of soils that must last long term, I immediately consider the percentages of organic:inorganic components. If I want a soil to last several years, I'll use something with more than 2/3 inorganic parts, like Turface, pumice, perlite, Soil Perfector, etc., and only 1/10 - 1/3 organic parts - usually fir or pine bark. For plantings of 1-2 years, I'll use a mix of primarily bark, peat, perlite.
Well, I certainly never intended to go on so long; and I know I bored some into leaving before they got this far, but for those that made it to the end, I hope my thoughts were clear enough to provide some insight.
Al Fassezke
Al,
do I get a cookie for reading the whole thing?
After the test. ;o)
al you get a box of cookies for typing the whole thing...
wah?! Cookie for reading, box for acing the test. lol
You didn't notice it was a copy/paste job from something I'd written previously. Hardest part was locating the text. ;o)
Al
Al
So glad you DID locate this piece. You do have an interesting way of explaining things.
I have to say that for someone who has had little interest in the "why" of gardening, I find myself developing an interest. So thanks for THAT too.
tapla, lol I remember reading your post somewhere else that you posted! I would say that the majority of annuals, and plants in general do not need high amts of phosphate-thinking of triple phosphate ( 0-46-0 ), but even 20-20-20 is too high in phosphate. Most annuals can't process that high an amt of phosphorus, so it goes unused. Its like Vitamin C-your body can only utilize only so much of it.
I grow annuals for a living-so I really need them blooming, and have no trouble having them bloom using the following liquid ferts each week: 13-5-13, 20-10-20. 21-7-7, 15-0-15. You can see that phosphorus is the lowest number in all of them. I don't use all of these ferts in one week. some are basic ( raise PH) and some are acidic ( lower PH) and I choose the fert according to the plant and the PH that I want the plant to have. Some have micronutrients that others don't have and I look at that as well. I never think about the phosphorus. Potassium ( last number) is more relevant-goes to the roots and the overall health of the plant, and you can see that most of the above ferts have higher numbers of that.
A plant needs fertilizer to prosper and grow well, and so you can assume that your annuals will need constant fert throughout the growing season. If you liquid feed-do it each week, esp if the plants are exposed to heavy rains thru the week, as that will leach out the fert. Don't fert really dry plants-water them first and then fert a bit later because when the soil is very dry, all the soluble salts ( that is the main ingredient in liquid fert) will accumulate at the top of the soil, and you are adding more salt when you fert. It is the salts that will burn a plant.
You can also assume that with the soiless mixes (and maybe the potting soil mixes -have never used them, but if they say for seedlings, then it would also apply) that even though it says that it contains ferts, that they are in very small amts that hardly count. When I transplant small seedlings into the soiless mix, I pick up with a fert program almost right away as I know that the starter fert will only last a week. It has to be a very small amt in there or it would burn small seedlings. I do start out with a weaker solution as the plant has very few roots, but will increase the amt as the plant/roots grow thru the season.
Tigerlily
Thanks for the additional information. Sometimes I thik th more I read the more confused I get. I've been using dry fert with lower Nitrogen thinking the N would only encourage green leaves at the expense of blooms.
Plants need nitrogen-if you want blooms, then with full sun plants-the more sun they get, the more they will bloom, and also cut back on watering. Watering is what really encourages foliage growth.
It can be confusing, and there is a lot of info to learn, but fortunately annuals are very forgiving plants, and they will perform pretty well under a lot of conditions!
Al,
do I get a cookie for reading the whole thing? Too..!LOL
Nice reading !
Thanks.
Didn't you know there's a test before the cookie part? ;o)
I'm glad you found the determination to get through it, and only hope you found something useful/helpful ...... and thanks for the kind words!
Al
Okay, so does no one use Osmocote? I've been adding that to my soil mix.
There are lots of formulas of Osmocote, so some are appropriate in certain applications and some are not. Factor in the fact that plenty of people call all types of controlled release fertilizers (CRFs) 'Osmocote' (kind of like millions refer to all sorts of tissue paper in a box as Kleenex) as a misnomer, and we see additional confusion.
CRFs have their good points and bad points. They are very dependant on temperature for delivery, but they are good insurance for those who might otherwise forget to fertilize when it's needed. I like to have complete control over what my plants get and when they get it, and you relinquish that option when you rely on CRFs for your supplemental nutrition exclusively, so I rarely use CRFs. CRFs are better when incorporated (into the soil) rather than broadcast (on top of soils), and using CRFs with inappropriately long release periods too late into the growth cycle can be problematic for plants you over-winter.
All in all, I'd sort of sum it up by saying it's probably better to use a soluble fertilizer with an appropriate formulation and skip the CRFs if you think you'll be diligent about making sure your plants get their supplemental nutrients on time or when appropriate. If you're going to use them, try to incorporate them into the soil, and don't apply them too late in the growth cycle for plants you're going to over-winter. IOW, don't apply a healthy dose of CRFs to your houseplants or containerized perennials you'll winter over in Sep. Use an appropriate NPK formula.
Al
Ha - you hit the nail on the head. It finally occurred to me earlier in the summer that perhaps my houseplants could probably (how's that for scientific?) use some fertilizer, so I dutifully measured out some brown liquid I'd been given at some garden show, added it to their water and poured it on. Found out last week that it's a foliar feed, sheesh.
So, no, diligent is not a good term applied to me!
Other than the Osmocote, my poor plants have pretty much limped along. Thankfully, they seem to be pretty forgiving, so far.
Thanks so much for the well thought/ well written out advice, Al - you have yet another fan.
PC - you didn't do anythinf wrong by applying the fertilizer to the soil/roots. Here are a couple of blurbs I wrote for and left on another forum site:
Some parts may seem off topic or might overlap what I already offered.
If you actually do NEED to supply nutrients via foliar applications for houseplants, there is either something gone awry with your nutrition supplementation program or there is a culturally induced deficiency, usually caused by the soil. Foliar applications are effective at supplying nutrients when they are both scarce in the soil and the plant is growing so robustly it cannot assimilate them quickly enough to allow it to grow at its genetic potential. More on this later, but there really is no reason you cannot supply all the known essential elements in one application to the soil, with a single product.
If you ARE using a fertilizer that supplies only a few of the minor elements, then a second application of a micro-nutrient preparation is advisable. Some lack several of the minor elements, and most soluble fertilizers lack both Ca and Mg, so these elements need to be considered, especially in aging soils.
It's best to supply nutrients in the same ratio that plants use them, unless you are using nutrition to induce a particular growth-related result. If you take an average of the ratio of NPK that a huge % of plants use, you'll find that they use it in a ratio of approximately 10:1.5:7. (ratios are different than the %s reported, though they are related) Since fertilizer formulas report phosphorus as P2O5, not actual phosphorus (P), and potassium is reported as K2O, not actual potassium (K), to convert P2O5 to actual P supplied, multiply the P2O5 value by 0.43, and to convert K2O to actual K supplied, multiply the K2O value by 0.83.
I said all that technical stuff so I could say that .... after the math is done, almost all plants use nutrients in something extremely close to a 3:1:2, NPK ratio, so fertilizers like 24-8-16, 12-4-8, and 9-3-6 (all three are 3:1:2 RATIOS) are excellent choices for almost all plants if your goal is normal growth.
and ....
The effectiveness of foliar fertilizers varies to the extreme. First, only some plants can absorb ions (and a few small proteins of little significance) through their cuticle and allow them to enter the nutrient stream. This means that only soluble solutions or the tiny ionic fraction of organic fertilizers like fish emulsion are able to pass through the cuticle of SOME plants and make it to the nutrient stream. Fish emulsion depends on micro-organisms in the soil to break it down into elemental form so it can be absorbed. These organisms are not present in measurable populations on foliage and would lack the moisture necessary to keep them viable anyway, so foliar applications of FE and other organic amendments are not measurably effective as a foliar spray.
To answer your question directly: Any fertilizer that supplies nutrients via foliage as the primary pathway would supply the same nutrients via normal root pathways.
Note that many nutrients are immobile in the plant (mostly micro-nutrients and Ca), so quick fixes like adding Fe (iron) via foliar applications may green up the leaves temporarily, but do nothing to actually relieve the deficiency the entire organism is dealing with.
Al
This may be helpful: http://davesgarden.com/community/forums/t/783660/
Very interesting stuff - is there any clues as to which plants can and can't take up foliar feedings - like plants with a waxy feel, or succulents or something? I know the particular stuff I was being sold on is being used in pasture and crop applications - and one daylily patch.
The plants with high levels of cuticular wax don't absorb foliar feeds well. Remember too, foliar feeding is a very inefficient way of getting nutrients to plants, and effectiveness also varies with what nutrients are being applied and in what form. If foliar feeding is required, or makes a notable difference, you (the collective 'you') probably should be looking closely at what might be wrong with your regular nutritional supplementation program because roots are by far the most efficient pathway for nutrients.
Al
Right on, got it. Thank you again!
With Spring somewhere in our future (Dear God, let it be so!), it may be an appropriate time to re-visit the original post in this thread. The original question was, when using a growing media which is also supposed to feed for several months, how long will the nutrient last? The sad truth is that in most cases, the nutrient will last through the first watering. Most of the "plus" brands of growing media contain "controlled release" or "slow release" fertilizers. The release mechanism of these fertilizers is usually the attainment of a certain soil temperature, most guaranteeing their nutrient release over a certain period of time based on a soil temperature of about 70 degrees. If you buy a sack of potting mix that's been sitting on a garden center parking lot, wrapped in black plastic for even a few weeks, the temperature of the media will most likely have exceeded 70 degrees by a bunch. There is evidence to show that slow release fertilizers can "release" up to 40X faster than the guaranteed rate if soil temperatures go from 70 degrees to 100 degrees, which can easily happen when the media is exposed to direct sunlight, be it in the bag or in your container on your deck in the middle of summer. That said, the nutrient will have "released", meaning that you're going to flush the released nutrient right out of the bottom of your container with your first watering or two. It's better to buy (or build) a growing media without nutrient, then use a nutrient appropriate for the type of planting you're going to do.
Good points. I agree wholeheartedly with Steve.
Al
Oh geez - don't tell Scotts that, they'll be so mad.... >smile< ...
Let 'em.
Yeah, well.... I wish they weren't so darn omnipresent with their miracle gro product. In rural areas like mine it's often tough to come up with anything that doesn't have it in it. Someone on a thread mentioned that they're putting it in the seed starting mixes, too, fer cryin' out loud.
You can't fault their distribution network; it's second to none. If you haven't done so, you should read up on the history of the old man Stern and the Miracle Gro story. However, I think you weaken your brand when you put the name on so many different products: gardening gloves, etc. Again, consider what's in the bag rather than on the bag.