Fertilizer

[Piper23]

I have an unopened container of "Miracle-Gro All Purpose Plant Food".

Looks like N-P-K is 24-8-16 and the suggested dilution on the box is 1/2 teaspoon per gallon.

Is this a good fertilizer and dilution for orchids?

Is there a more appropriate fertilizer?

Does the choice of fertilizer depend on time of year?

[Dimples]

That fertilizer formula will be perfectly suitable for your orchids, so long as your tap water has calcium and magnesium in it. If you google your city/town and “water quality report 2022” to the search, you should be able to find the most recent report. If your water supply doesn’t have sufficient Ca/Mg, you’ll have to supplement with a separate cal/mag formula.

---------- Post added at 02:00 PM ---------- Previous post was at 01:58 PM ----------

And 1/4 teaspoon is probably going to be a better dilution, unless you only fertilize occasionally.

[Piper23]

Thank you! I have read that weak/weekly is a good approach- should I dilute the Miracle-Gro, or should I use it as the manufacturer suggests?

It looks like I will need to supplemnent Mg and Ca. Can you suggest a supplement?

---------- Post added at 05:47 PM ---------- Previous post was at 05:45 PM ----------

My bad- I just saw your suggestion for 1/4 tsp.

I would appreciate any Mg/Ca supplements that fit the bill.

[Dimples]

There’s a few on the market but I like the one from Botanicare.

---------- Post added at 03:22 PM ---------- Previous post was at 03:19 PM ----------

And you will want to apply it separately from the other fertilizer. Mixing it with the MG could cause precipitation of nutrients out of the solution, which is wasting your money and not helping your plants.

[Ray]

Originally Posted by Piper23

I have an unopened container of "Miracle-Gro All Purpose Plant Food".

Looks like N-P-K is 24-8-16 and the suggested dilution on the box is 1/2 teaspoon per gallon.

Is this a good fertilizer and dilution for orchids?

Is there a more appropriate fertilizer?

Does the choice of fertilizer depend on time of year?

It is perfectly adequate for orchids. Fertilizer is WAY down the priorities for orchid growing.

How MUCH you feed is related to how OFTEN you do so. Based upon 50 years of experience and the "melding of the minds" of some serious growers, I have concluded that 75-125 ppm N applied weekly is a good target.

If you divide 8 by the %N in the fertilizer, the result is teaspoons/gallon for the middle of that range, so there's room for rounding to make measurement easier.

8/24=1/3 tsp/gal, so the use of 1/2 tsp/gal once a week would be 150 ppm N, a shade high, but not out of the question. If you applied that every two weeks, that would be a weekly equivalent of 75 ppm N, which is the bottom of the range and still acceptable.

There is absolutely no reason to change formula with the season.

[Leafmite]

The only exception to changing the amount of fertilizer is if you have less light (less light often means slower growth) or an orchid like Cattleya dowiana that needs a rest period or goes dormant.

[Ray]

Originally Posted by Leafmite

The only exception to changing the amount of fertilizer is if you have less light (less light often means slower growth) or an orchid like Cattleya dowiana that needs a rest period or goes dormant.

100%

[Zoren]

Ray, I hope you had a good Thanksgiving. I'm still a little/very confused (probably my age) as to how much fertilizer to use, as I have said before my watering schedule is usually once per week. I use distilled water from my A/C overflow into a gallon container, and the TDS in the gallon container is anywhere from 5 to 13 ppm. I'm not sure how much of your K-Lite fertilizer to use. I have been putting a little more than a 1/2 teaspoon, (today the TDS readings were between 50 and 62 ppm), the PH was about 5. Ray, should I put more fertilizer into the water to reach the 75 to 125 ppm, or is what I'm doing alright (I don't want to burn the roots of my plants)? Today I added Kelpak (1Tbs/gallon) based on instructions. Waiting for your reply , Zoren.

[Ray]

Originally Posted by Zoren

Ray, I hope you had a good Thanksgiving. I'm still a little/very confused (probably my age) as to how much fertilizer to use, as I have said before my watering schedule is usually once per week. I use distilled water from my A/C overflow into a gallon container, and the TDS in the gallon container is anywhere from 5 to 13 ppm. I'm not sure how much of your K-Lite fertilizer to use. I have been putting a little more than a 1/2 teaspoon, (today the TDS readings were between 50 and 62 ppm), the PH was about 5. Ray, should I put more fertilizer into the water to reach the 75 to 125 ppm, or is what I'm doing alright (I don't want to burn the roots of my plants)? Today I added Kelpak (1Tbs/gallon) based on instructions. Waiting for your reply , Zoren.

Sorry to disappoint, but your TDS meter is of (nearly) zero value in measuring fertilizer concentration. (read this)

If you feed weekly, my standard recommendation is to apply 100 ppm NITROGEN. With K-Lite, the TRUE TDS - the mass of the solids left behind when one liter of the solution is fully evaporated - of a 100 ppm N solution is 0.77g which is 770 mg, or 770 ppm

If you put a level 1/2 teaspoon of K-Lite in a gallon, that would be about 120 ppm N, and a true TDS of about 920 ppm. Nothing to be concerned about.

[Zoren]

again Ray, based on your reply 1/2 teaspoon K-Lite is fine. Thank you: waving, Zoren