violetsnbunnies

Superthrive, kelp, humic acid, mycorrhizae...what are your thoughts?

Violets N Bunnies
2 months ago
last modified: 2 months ago

I’ve been reading about soil amendments and fertilizer additions that may give African violets an extra boost. Does anyone have experience/ advice on using any of those I mentioned above specifically for African violets? Do you use something else that you can recommend? Thank you in advance!

Comments (19)

  • irina_co

    Nothing works better than just plain old good culture. Doing everything on time. Regular repotting. Switching to lights instead of windowsills. Good soil. about 6.6 pH. Weak regular fertilizer. Epsom salt every so often.


    Regarding the list of additives. Supethrive is an excellent to soak and spray the cuttings. It stimulates the root growth, good thing to have when you are in a propagation stage. Adult plants develop brittle leaves if you do Superthrive on a regualr basis. Active ingredient - kelp extract and vitamins. So - I bet kelp works the same.

    Humic acid s a by-product of a peat moss kept wet. It will develop naturally - since the peat moss is one of ithe main ingredients of AV mix. Eventually with time it will turn the soil acid - that's why we repot AVs to get away from the low pH. So - nah, we already have it.

    Micorrhizae is not bad, the only question - is it the right one to be symbiotic with AVs? Even it is not - it is not going to harm. You will see the presence of fungus in a soil - little white globes - which can be confused with root mealy bugs - and put you in a risk of a heart attack - but they are irregular and do not move... whoosh... not it.


    Violets N Bunnies thanked irina_co
  • Violets N Bunnies

    I appreciate your detailed response, irina_co. It was really helpful. Sounds like what you’re saying is simplicity is best and just to get good, basic care down pat. I guess I’ll focus on that for now and try not to complicate matters. I’m finding that even achieving the basics are difficult. I’m still struggling to find proper indoor lighting...

  • irina_co

    Hear -hear. I am all for well done mashed potatoes with gravy - makes me happy every single time.


    Proper indoor lighting is 2 T12s 8-12 inches above the plants... cool whate/warm white. Since T12s are phased out - we try to adjust to what is available - 2T8s work too - but they are brighter - so higher above is an answer. With LEDs ...they are all different and the spectrum is - who knows what is the spectrum of each... but generally lowering them or lifting them works too. And they take less power.

  • Violets N Bunnies

    Thank you again for the lighting advice, irina_co. I actually recently purchased an LED grow light and it has done wonders for my AVs. They went from never blooming on my window sill to bursting with buds under the new lights in just a few short weeks! The only problem is some of my plants have really thrived, while others got scorched and droopy. As a new AV grower there’s so much to learn, but I’m enjoying doing it!

  • irina_co

    There is a different light requirement for different varieties. Usually light green leafed varieties burn easier - so you move them to edges of your shelf to find a sweet spot for them. Grow LEDs - are probably too intense for AVs, try to raise the fixture higher.


    Irina, too cheap to buy grow LEDs.

    Violets N Bunnies thanked irina_co
  • Violets N Bunnies

    Lol! irina_co, the LED lights I purchased from amazon were surprisingly inexpensive. I don’t have much extra $$$ to put towards my new hobby with my having to purchase plants online and shipping them all the way to Hawaii (there are no AVs here). The LEDs were only $16 with a fair amount of good reviews. They’ve worked wonders for my plants as I mentioned before. You are right tho — the plants that were scorched were mostly light green and variegated. I’ll go experiment and find them a safer spot on the shelf. Thanks again!

  • irina_co

    I got some 24 inches single LEDs in Home Depot - I think in in $16-18 range - burt they didn't have the cord - so I needed to attach it myself - while the whole fixture with 2 tubes and GROW LEDs hads an obscene price - like $200.

    The fact LEDs are "GROW" means it is usually high output cool lights people use for growing weed... which is a full sun plant. It will work if you increase the distance from the light to the plants. Twice the distance - 4 times less intensity.


  • cocrazywoman

    I just recently got 4 ft LED shop lights from Costco for about $28 each. Do you have that option? They are brighter/stronger so you do need to have them further away. Before that, the cheapest was $47 a light at The Home Depot (which didn't come with all the mounting hardware, Costco ones did).

  • Violets N Bunnies

    Just curious...how do you determine which regular lights (not labeled specifically as grow lights) would be good for plants?

  • cocrazywoman

    In the research I've seen the most important part is the "brightness" of the light. I use Daylight fluorescent bulbs that are 6500 lumens. I look for that same rating on the LED lights. The fluorescent bulbs degrade over time and are markedly dimmer in as little as a year and the tubes must be replaced. This way I can use them for seed starting. African Violets need less light so you can put them 12-15 inches away from the light. Seed starting has those bright lights within a few inches from the seedling. If only using them for AVs, you could go dimmer. I've used grow lights before and never really saw a difference. The only difference I've seen in the plants is when the light is too dim or too bright. Maybe someone has a proven test with the light spectrum. I never thought the grow lights were worth it.

  • Violets N Bunnies

    Thank you, cocrazywoman, for the lighting advice. I’ll keep that in mind the next time I go to my local hardware store. Do you have an opinion on light color — warm or cool?

  • cocrazywoman

    That is the light spectrum. I've found the daylight bulbs at 6500 lumens to be the best. No need for warm/cool or use LED.

  • irina_co

    Plants use these wavelengths.


  • irina_co

    Day light tubes - the spectrum is more or less evenly distributed on all waves - imitating sunlight - very comfortable for people, For the plants - the light besides 400-500 and 600-700 nanometers - is wasted. Growlight -enhances energy in these wavelengths,

    The good part - as long as the light is not too weak and not too bright - plants will use whatever they need - and bloom happily.

    When Costco was just starting to sell their FeitLED fixtures - they were 4200K - so the spectrum was more strong in a bluer part - and they burned plants. I think now it is more like 3700K and these are less harsh.

    There is another issue with LED - each diod emits light in 30 degree angle - while fluorescents - 360 degrees - so with reflectors - fluorescents give better light distribution - LED - the intensity drops significantly on the edges.



  • gardengal48 (PNW Z8/9)

    Coming from a professional horticulturist, I agree almost entirely with irina :-) Nothing supersedes proper culture and care. Proper heat and light, proper potting soil, proper watering and proper fertilization. Amendments for any kind of houseplants are almost always unnecessary. And in some cases, can be counterproductive.

    Mycorrhizae is completely ineffective in an indoor container growing situation with a soil-less potting mix. Won't hurt but doesn't help. Save your money :-)

    Superthrive (aka 'Superjive') is just heavily promoted snake oil. All it contains are some rooting hormones and B1. And you dilute it down to where it is almost nothing but pure water anyway!! B1 is not a necessary plant additive (plants make their own) and a rooting hormone is only necessary if you are rooting. Save your money :-)

    Kelp or any other organically derived fertilizer is highly inefficient in an indoor container situation for the same reason myco is - no active OM so none or insufficient populations of soil microorganisms to convert it into a plant usable form. Same with humic acid........can be beneficial in an outdoor garden setting but pretty much useless indoors. Save your money :-)

    And despite all manner of scientific literature to the contrary, the belief that adding Epsom salts somehow makes plants grow better/stronger/faster is a myth that resists being broken. Epsom salts - magnesium sulfate - is only of benefit if you have a magnesium deficiency. Period. And for any containerized indoor plant, that is easily addressed with a full range fertilizer. Save your money. Or save your Epsom salts for the bathtub soak to relieve the sore muscles you got while gardening outside :-))

    Violets N Bunnies thanked gardengal48 (PNW Z8/9)
  • Violets N Bunnies

    Thank you for your advice, gardengal48. What about the idea that Epsom salt would help “green up” a plant...do you believe this is a myth, too? I’ve read that over and over again, and I was about to try it with a very pale variegated African violet...

  • dbarron

    To reiterate GG:

    If you feel your fertilizer regime lacks magnesium, then yes, otherwise no.
    And if you do, you should fix your fertlizer regime versus giving it epsom salts, because you're likely to be missing a range of micronutrients if you're missing Mg.

  • gardengal48 (PNW Z8/9)

    To expand just a touch on dbarron's comments.......and to address the "greening up" :-)

    A magnesium deficiency can present as chlorosis or a yellowing or lack of color in the plant's foliage. It is also one of the fundamental components of the chlorophyll molecule, which is what makes plants green. So a lack of magnesium in the soil could account for a lack of good color. That part of the 'myth' is true enough. But if you are using a good fertilizer regularly - something like Dyna Gro's Foliage Pro 9-3-6 - you will be supplying all the magnesium necessary for plant health without needing to resort to unnecessary additives. And applying Epsom salts unnecessarily or without calculation can result in excess magnesium in the soil and that can adversely affect the uptake of more critical plant nutrients. Using a quality fertilizer like the Dyna Gro with a full range of necessary plant nutrients and in the proper proportions will make sure your plants are getting exactly what they need - no more and no less.

    What is important to understand with all the Internet comments and reports of plants "greening up" with applied Epsom salts is that it is all anecdotal. It is not done under the controlled conditions scientists use to evaluate the actual benefit of any amendment or chemical element. We have no idea what the specific growing conditions are or what other cultural care has been provided that could account for the same result, like supplying more water.......or sunlight. Or using a good fertilizer :-) It is just a false assumption that if I use A, B will be the expected result. There may or may not be a direct correlation.

  • irina_co

    Agree with most. Usually with a good culture - you do not need to green up anything. The problem is with variegated plants - sometimes the plantlets come up mostly white - and only live as long as the mother leaf is working. Sometimes it helps to use snake oil - fish emulsion, Epsom salt, foliar feeding - to start producing green leaves - since it is a race against time.. And sometimes the whole plant goes into variegation mode... and croaks. I lost Tiger's Son this way, Alan's Fallen Angel and Cherokee Trail as well. Older varieties... So... when they went white - and I really treasured them - I would try everything on the list....





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