I grow many hundreds of tropical plants (over 500 orchids), and my rule of thumb is to fertilize 2-3 times (1/2 to 1/4 recommended dilution) and then to flush with clear water. Adenium are new to me, so I don't have a clue if that regimen is suited to them or not.

I guess it might be the same for all plants. Perhaps not the solution, but the flushing is I guess. To much salts in the water otherwise I did learn now.

Is it time to do something with this particularly plant? It is about twice as tall as the other 18 plants (9" from the soil-line), shows no tendency to branch, and the caudex is a bit over 1" wide. This is the only one I did not re-pot and thus the roots have not been touched.

"The higher concentration of salt outside of the plant cells in the soil causes water to move outside of the cells to try and equalize the concentration. Some root cells of plants that do not tolerate salt may die, and if bad enough the plant will die. The damage gives the plant a burnt look, often on the leaf edges first. The same thing happens with too much of any mineral."
Source

drdawg said:Is it time to do something with this particularly plant? It is about twice as tall as the other 18 plants (9" from the soil-line), shows no tendency to branch, and the caudex is a bit over 1" wide. This is the only one I did not re-pot and thus the roots have not been touched.

Ken, I would leave her be...since her roots have not been disturbed
she will be the first of your adeniums to flower.

Okey, dokey. I will leave her be.

I hope she will bloom soon for you Ken. Good luck.

Thanks, Willeke. I am just happy to be able to grow these.

Me too Ken. Keep learning all the time.

Rainbow said: ... I agree that flushing the plant's soil media with rain or filtered water from time to time is a good thing.

Because of previous experiences, I shy away from using chemical fertilizers...they have a high salt content. Two of the fertilizers I use now are bone meal incorporated into the soil media at transplant, and fish emulsion liquid about every 4 weeks. As far as I know, these do not have salts.

Many people agree with you!

And some say that feeding plants organically requires soil organisms like fungi that do not thrive in pots, and generally don't live in soilless mixes. Do you have real soil in your pots or a soilless / soulless mix? Of course, if you are growing in SOIL in pots, the soil needs organic matter, and feeding only soluble chemicals would starve the soil life and "kill" the soil.

I know of one guy who puts real soil into pots, and keeps it "alive" enough that worms also live in his pots!

One web site claimed that fish emulsion is already "broken down" as sold, hence does not need fungi to digest and release it. If that meant that proteins were already broken up into amino acids, it would be VERY salty (in the sense of total ions, not NaCl). Like beef bullion. I don't know.

Organic fertilizers might release their nutrients more slowly than soluble chemical fertilizers do, reducing the risk of "burn".

And probably many people read the instructions for soluble fertilizer, add the 1/4 tsp called for, think "That's not much!" and then add 2-3 times as much, killing the plant and blaming the chemicals. I notice that every experienced or commercial grower mentions that they dilute chemicals 2 - 4 times more than advised on the label. And that they often water with straight water, and also know to flush out their pots periodically.

So MIS-using chemical fertilizers may be more to blame for many people than the fertilizers themselves.

The nutrients mostly ARE the salts that we want to avoid accumulating, except for Na and Cl. Maybe Ca in some soils. The soluble "chemical" fertilizers are just more concentrated.

If you loaded up on enough organic fertilizer to equal the amount of mineral nutrients in (for example) a 1/2 tsp of soluble Miracle-Gro, I think that even fish emulsion would release almost as many (nutritive) salts as the soluble fertilizer does. Maybe over a longer period of time, and hence with less risk of burn.

My opinion is that BOTH kinds of fertilizer should be used with the same concerns:
(1) don't add too much
(2) pick nutrient ratios close to what your plants need, or the excesses will accumulate as toxins
(3) don't use any brand that contains much NaCl, or that won't publish that measurement on the box.

I searched briefly for NaCl content of different fertilizers (chemical and organic) but didn't find useful sources. I know that in some regions, even manure is considered a slainity risk, so cow poop DOES have enough NaCl to be a potential problem.

Many Internet sites talk about organic fertilizers "not adding salinity". I question that. If they add any N, P or K, or Mg, Ca, Fe, or SO4, they add ions, which are salts, which is what is meant by "salinity".

If they meant "no NaCl", I wish they would say that and give numbers, since EVERYTHING has some NaCl and most organic matter has a fair amount. Our own blood approximates sea water's salinity, though I suspect most plants contain less NaCl than we do. Instead those sites talk as if plant nutrients were not ions, and hence were not salts. That's plain wrong. If fish emulsion truly did not add any ions (salts), it could not add any plant nutrients.

So as soon as I see words like that on a website, I question everything else they say too. Maybe they are just making unstated assumptions and glossing over unstated issues, but the words are as plain wrong as they are frequently stated.

There must be SOME truth to the idea that organic fertilizers don't burn plants as often as "chemical" fertilizers do, because SO many people believe and repeat the myth "organic ferts add no salinity".

I speculate that no one CAN get all the salt (NaCl) out of fish, but I might be wrong. And I think that high-end soluble hydroponic fertilizers very carefully limit the amount of unwanted ions (mostly Sodium and Chlorine) they include, because total ionic content is a huge concern in hydroponics.

Also, in outdoor gardening, I agree with you. I would rather add compost than fertilizer outdoors, IF I have enough compost.

There is a way that soluble fertilizers might add more (non-nutritive) salts than organic emulsions. Maybe some cheaper soluble fertilizers use cheap salts that include Sodium or Chlorine or other ions that are not taken up by the plant. THOSE would accumulate in pots more than they would from organic emulsions containing smaller amounts of Sodium or Chlorine.

Also, plants only take up what they need, in the ratios they need them. If the emulsion fertilizers have very well-balanced N-P-K in the ratios that your plants need, few will be "left over" after the plant has taken up what it needs. IF some soluble chemical does NOT match your plants' needs, then the limiting nutrient will ALL be consumed and the excessive nutrients will be "left over" and accumulate like ions that the plant does NOT like to take up.

Now this is the "RickCorey" I know!

Thank you, thank you, for elucidating! Very enlightening and thought-provoking information!

I now have brain-lock.

Me too Ken.
What a lot of information. How do you know what npk ratio Adenium do need. I have no idea? Someone enlighten me please.

Very good question, Willeke! I've been trying to figure it out through my trials and tribulations.

Well Kadie. Hopefully there is a answer somewhere. I am so afraid my fertilizer has a to high npk ratio.

That's a very good reason to dilute it by 1/2 or even 1/4. Call it "NPK Insurance". Remember the phrase "Weekly-Weakly".

I apologize that i just CAN'T say things briefly. Sometimes I can come back a day or two later and produce an "executive summary" with only the most relevant points.

>> How do you know what npk ratio Adenium do need. I have no idea?

Right, I don't know either. Plant scientists and people making a lot of money from hydroponics have their ways.

1. Analyze the plant tissue chemically. Everything except water and CO2 came from the fertilizer, so it must have taken up whatever is in the mature plant. Make the fertilizer match the plant tissue.

2. Grow the plants in a lab setting, probably hydroponically. Measure every milligram of what you put into the water. Measure every milligram of everything in the waste water. Figure that if you put it in, but it did not go down the drain, the plant must have taken it up. Whatever the plant did NOT take up, was in excess.

Be sure to do this for the seedlings, the vegetative growth phase, and the fruiting/harvest stage.

Now apply for even more grant money to do it again for the next plant variety.

3. Get real and do it Rainbow's way. Grow some plants using whatever, say 23-8-16.

Do it again using fertilizer with some other ratio.

Whichever one did better, use as your next starting point and try more of one thing or less of something else. See which works best.

My guess is that the first two methods don't always tell the whole story, and even plant scientists get their CORRECT answers by tweaking the answers from the first two methods using Rainbow's method.

I don't know if any soil testing labs would be willing to analyze the water coming out of the bottom of a pot. They MIGHT be able to tell you that the plant took up ALL the N, but there was left-over P and K.

Thanks again, Rick Corey!

I can say this much at this point in my trials and tribulations:
Young adenium seedlings do not require as much nitrogen as older plants. In fact, giving too much may etiolate their stems and branches. This is neither attractive nor a desireable growth for adeniums.

Older plants do need nitrogen for it to be able to flower. But a weak solution is best so that elongation will be limited. Then again, Adeniums are quirky! Some will etiolate their stems anyway, some won't...it's mostly in the predisposed genetics of these plants...they all differ. Amazing plants indeed! And certainly very challenging!

Thank you!

At least I held my first post down to "only" two pages.



It sounds like you could write an article on the nutritional requirements and psychological quirks of Adeniums!

Oh, wait:

The thread "Rainbow's Chronicle: My Adenium Culture" in Adeniums forum

Never mind!