So this will be my second year fertilizing. Last year I bought 10-10-10 granular fertilizer and followed the directions, which said to put half a cap full for every 1-2'' of trunk width, for container grown plants. Well it burned the 4 trees I used it on, slap up!! Now I'm scared to fertilize... I bought this osmocote today with an even balance of npk 14-14-14. The directions for shrubs and trees say to use one cap full for every 2 feet of branch spread. Im assuming thats for trees planted in the ground and I definitely dont have that much of a foliage spread on any of my bonsai trees. So my question is, how do I use this stuff?? What the best way to measure it out for bonsai use? I dont want to over fert. How do you guys specifically use osmocote?? Thank you so much in advance. Im really struggling with the fertilizing part of bonsai practice.
So 3yrs later- are you still using Osmocote? If not, why? Hoping you get updates via email because you're 2-months inactive but figure there's a good chance the average user gets email updates
(just switched from an all-liquid fertilization regimen to osmocote, w/ the intent to have it be the majority of my fertilization (and just use instant miracle-gro as a 'boost' selectively)
I just cover the surface of the soil in the pot (maybe 60%) with it, then I fertilize it every other week with liquid Miracle-Grow too. What makes you think your ferts "burned" your trees ? Were they Maples that got burned from the sun maybe? I have never seen fertilizer burn anything, from Crepe Myrtles to Bougies, as well as Junipers and Ficus down to my Chinese Elms and even my Yaupon holly or my Malus (Apples) I literally fertilize the living shit out of them without a hitch.
ed
Which osmocote (%'s) were you using? I just got their 15-9-12 'osmocote plus' and applied to my entire garden, I applied on the light side figuring I can apply more later but can't remove excess....but then I read you saying you cover the surface @~60%? It doesn't read like hyperbole but wouldn't that be like 5x the label rate? Forgive my ignorance on this, I've relied on liquid miracle gro (24-8-16) for ages and wanted to switch to something where most of the fert comes 'extended release' and then I can just do an every ~5-10day liquid application, am really trying to push growth, am in FL and growing mostly bougies and crapes like you mentioned...would love to know if you still use the stuff and any thoughts you've got on it, my first application was my best attempt at ~70% of full-strength rate (just guessing 'gallons' of substrate by eye..), feel like I may've seriously under-done it - am at least going to do another single application (of roughly the same strength, so a ~140% recommended-rate) on a tester-plant, probably my large crape which is growing very fast & strong right now
On the same subject, I was in the camp of don't use too much inorganics but now I am questioning that. I thought why do I think that? Is it because its what I have always heard, though never experienced. So I am performing a test of sorts. I have 9 shimpaku 3 year old cuttings. 1 is in the ground, 7 are fertilized with moderate amounts of osmocote. The last is the special one. I put about 2/3 a cup of Osmocote on it. It is in a 3 gallon pot. I wanted to see if what I thought was correct and how far you would have to go using Osmocote to actually over-fertilize. So we shall see what the future holds. Stupid, maybe. But I will learn what that ultimate threshold of too much is. The potted plants are all in Napa Oil Dry (not a huge fan) and I also just started using Great White, Mycorrhizae supplement on all my trees.
Would love to hear how your trials w/ osmocote played-out, am basically in your same growing-area and wanting to switch to osmocote as my primary fertilizer, would love to know what became of the shimpaku in a 3gal that got 2/3cup! (and would love to hear if you ever found Great White to be useful? Am unsure how long myco's hyphae networks take to be 'established' and recall it being rather long, so anything that can 'seed' that effectively is great for container gardening especially mostly-inorganic bonsai substrate containers!)
I was using Miracle Grow 20-20-20 at 7 to 10 times recommended dose for a couple of years. I switched to Grow More 20-20-20 for a few years at high dosage as well. I do not remember when I finally went to Jacks Professional 20-20-20 with Micro Nutrients but I think I am entering the 2nd season now(it does not foam up when mixing). With that one I have been using 5 to 7 times the amount stated. I find I see no ill effects... Perhaps it is mostly inorganic substrate BUT not everything is in total inorganics. Based on several years of playing I do not see it possible to over fertilize if the substrate is free draining and porous enough to retain some. My Wife uses Osmocote on most all of her Tropicals and I never see her measure - she tosses in on liberal about 3 times in the Summer and once Mid Winter.
Bottom line it I find it hard to believe the fertilizer itself caused ill effects...
Grimmy
Love hearing that you used that much MG w/o ill-effects, makes me think my idea of 'super-feeding' (which is my goal right now, all my trees are in early development still) is wayyy lower than what it should be...And while it's true it's not
fully inorganic, the total CEC of mixes is so darn low that, so long as there's a reasonable minimum-particle-size for the substrate, what you (and walter pall) say is the case - am just so damn hesitant to put down what I'm starting to
think is a 'high dose' of osmocote ('high' in general), am hoping to strike a balance of like 60-75% of my fert from the osmocote and the remainder from weekly miracle-gro 24-8-16 instant feedings but am starting to think maybe I should aim lower / rely less on it because it'd be too easy to over-/under-shoot the amount as well as the stuff not being as consistent a release-rate as one would like... Seeing
@parhamr 's pics (first post of this page), especially that 2nd one, makes me think I wayyyy under-did it, I must've done <10% of that (though he's doing that application 1x/year...but also is in OR whereas I'm in FL...am curious to see if I'll be able to visually see the osmocote pieces get smaller over time, not knowing if the pellets are 85% spent at 6 weeks is a big deal if relying on them as a primary fertilizer!)
And for the OP's case, couldn't the fert have been the culprit
if there were dry-pockets or damaged roots? It sounds like he put down an instant-release 10-10-10 product measuring by the cup to put right on the soil, if the roots were dry or not in good shape I'd have to imagine it's possible, I mean my instant-release stuff hurts cuts on my fingers, if you just laid that down on hurt roots (I know his was half that strength but still) it seems reasonable enough it could've been the 'death blow' to already-distressed trees..
