How to handle fertilizer burn?

[KC Kam]

Hi All,

I have something that I need you all to help to clarify abit. Previously I've been using 21-21-21 fertilizer with 1/4 strength dilute in water and water directly. Everything seems fine for few months.

Until recently I got a new fertilizer known as orchid booster. I also use 1/4 strength and after 3-6 application over the span of 2 weeks some of my orchid root tips turn brown. I stop fertilizing and has been flushing with plain water for 2 days nw. It happen mostly on hanging root tips and those that dry up slower due to recent cooling days in my area where water evaporate slower.

I have a friend that uses the same fertilizer but he fertilize almost 1/3 of the strength yet nothing happen to his orchids. He did mentioned his place has strong wind and he only fertilize once a week. I believe his environment is more windy, that why he does not have such problem? Does the orchid really absorb more fert compare to mine 1/4 strength?

Does it mean that after flushing I should continue with 1/4 strength? or reduce the strength furthermore? When should I continue fertilizing?

Pls advice..

[bil]

Go here and start reading up. There are a lot of pages on fertiliser, and it is an excellent resource to bookmark.

Nitrogen Management Calculator - First Rays LLC

That particular page is a nitrogen calculator. Use it to work out what you need. I use about 20-25ppm N at every watering, and that will do for all orchids bar a couple of specialist heavy feeders.
It works out at about 1.25G/ccs of dry fertiliser in a 6.5 litre spray.

[Ray]

"1/4-" and "1/3- strength" are meaningless terms. What mass- or volume per volume?

[estación seca]

I'm not sure you have fertilizer burn.

I agree you should read what Ray, who posted above, wrote on fertilizer use. Then you will understand why terms like "1/4 strength" are not useful.
Feeding and Watering - First Rays LLC

[KC Kam]

Hi Estacion,

Noted. I did read thru. Thank you for the recommendation.

Hi Ray,

I read through your sharing on the Plant feeding regimen. I attached the volume by ppm of the new fertilizer i used and below was my watering regimen.

Sunday - Water + pesticides
Monday Gaviota 63 (21-21-21) with 1/4 water + thiram (fungicide)
Tuesday - New fert as attached (1/4) strength
Wednesday - Flush with plain water (no nutrients)
Thursday - New fert as attached (1/4) strength
Friday - New fert as attached (1/4) strength
Saturday - New fert as attached (1/4) strength

I got to understand that your recommended ppm was 105 ppm per week. My weekly fert accumulation with the water regimen above has hit more than required. Furthermore the accumulation of Thursday till saturday itself too has already hit more than required. My friend applied 1/3 weekly but my 1/4 (multiply by 4 watering) over a week was actually more than him.

Please correct me if i am wrong.

In that case i should be adjusting by regimen to the below:
Sunday - Water + pesticides
Monday Gaviota 63 (21-21-21) 1/5 strength + water + thiram (fungicide)
Tuesday - Gaviota 63 (21-21-21) 1/5 strength + water
Wednesday - Flush with plain water (no nutrients)
Thursday - New fert as attached (1/4) strength
Friday - New fert as attached (1/4) strength
Saturday - Flush with plain water (no nutrients)

What do you think?

Please advice.

[Ray]

My recommendations are as follows:

• Stop using pesticides as preventive treatments.
• Cut the fertilizer concentration WAY back, and use it at every watering.
• Flood the plants at every watering.

Divide 2 by the %N on the fertilizer label. The result is the teaspoons per gallon for 25 ppm N. If you prefer metric, use 2.3/%N for ml/L. You may safely use that at every watering, and flooding the pot is the flushing, so there is no need to do that separately.

[KC Kam]

Hi Ray,

Noted on the pesticides. I will only use it when there is pests.

As for the fert dosage recommendation, i am still not very clear. As of now, i am using the below dosage:
Gaviota 63 - recommended was 1 teaspoon (5 gram) to 1 gallon / 4 liter water. But i am using 1/4 strength which was 1-2 gram per 4 liter water.

New fert - recommended was 1 teaspoon (5ml) to 1 liter water. I am using 1/4 strength which was 1.25ml to 1 liter water.

I am using sprays to spray them to the roots only.

What do you mean by there is no need to perform flushing separately? You mean to flush the pot after watering?

[Ray]

As frequently as you water, I would recommend 1/10 teaspoon/gal of that 21-21-21 formula.

If you use that dilute of a solution, and are very thorough in your watering, that solution will feed, water, and flush all at the same time.

[KC Kam]

Hi Ray,

You've enlightened me. Now i understand.

By the way, since ive over fertilize them, should i flush with water for a few days or i can straight away start your recommended watering dosage? My concern is not the medium because i can soak or flush it but was the dosage that the plant received previously.

[Ray]

Personally, I'd flood them with plain water for the next couple of weeks. No plant will suffer from that, and it will help flush residual fertilizer from the medium, while keeping it dilute around the plants' roots.