Seeking knowledge regarding feeding of Astrophytum, Lophophora, Ariocarpus, Copiapoa and Trichocereus.

[DaveW]

Steve said "and the ideal NPK ratio (balance) of 1:0.4:1.5 was a major revelation."

Hi Steve, maths was never my strongpoint as I did not have enough fingers to count on and people don't seem to approve of you taking your socks off in public for extra digits! LOL

We tend to use things like "Levington Tomorite" for cacti, a tomato fertiliser in the UK originally made by Fisons before they were taken over.

Looking at the ingredients it says:-

Low nitrogen fertiliser 4-3-8

Nitrogen (N) total 4%. Ureic nitrogen 2.1%
Phosphorus (P) soluble in water 1.3%. Phosphorus pentoxide (P2O5) soluble in neutral ammonium citrate and water 3% (1.3%P)
Potassium (K) soluble in water 6.6%. Potassium oxide (K2O) soluble in water 8% (6.6%K)

Dilute 20ml in 4.5 litres (1gallon) of water (I use it half that strength for cacti)

How does that compare with your ideal formula quoted above. If not what should I add to it or dilute it too?

[HudsonLH]

Steve,
May I ask what the rationale is behind the relatively higher N and lower P? The ratios are contrary to peer-reviewed literature I have read.

Narubest,
I do not know why cacti placed in full indirect sun will etiolate... it is strange. Without seeing pictures I can only suggest using a lux meter to measure the light your cacti are getting. It may be that they receiving less light that you think. I personally do not see how soil mixes, a balanced slow-release, or reasonable amounts of cal/mag will lead to cause etiolation. I live in the tropics, use peat in my mediums, fertilise heavily, only use LEDs and my columnars are not etiolating.

May I suggest that you also reach out to Thai nurseries for advice more specific to your environment? A lot of our experiences come from growing cacti in the Western hemisphere which may not be applicable to you. Uncle chorn and weerapat wiriyajarn were very accommodating once I made a few purchases.

H

[jerrytheplater]

Hi Jerry,
Thank you for your response. It seems that I am in luck! The P portion is indeed P2O5. I have ordered a 500 gram potion of the product last night!. This is the product in question, It has a western name but I am not sure whether it is a product on the western market. Upon searching the internet to find out more about the product I learnt that the instructions are to mix 3 grams or 1 teaspoon in 1 liter of water and apply as a foliar spray every 7 days. I would think that apply chemical fertilizers to the skin of our cacti would cause build up of some sort and perhaps burn the plant over time. Am I wrong to assume that? Have you heard of feeding cacti only through foliar feeding?

Narubest

Hi Narubest

You did not say if the Potassium (K) is reported as K20. I'm going to assume it is, but I am only going to calculate NItrogen. I am also going to assume you are using a dry granular product since the label says to use 3 grams per liter. We don't usually weigh liquids!!

16% N in your fertilizer = 160,000 mg N per Kilogram fertilizer. Which is also 160 mg N per gram fertilizer. Your label says to dissolve 3 grams fertilizer in one liter water. That comes out to 480 mg N per liter of fertilizer to apply to your cacti. That is 480 ppm N!!! Way too high!!!

To get to a more reasonable 50 ppm N, you should dissolve 0.3 grams fertilizer in a liter to fertilize your cacti by watering your pots. I do let my fertilizer water wash over my cacti, but I don't grow any with a bloom on the surface that might be damaged and I am only using 25 ppm N. I also water in between fertilizing with plain water which rinses off the plants.

[jerrytheplater]

Steve said "and the ideal NPK ratio (balance) of 1:0.4:1.5 was a major revelation."

Hi Steve, maths was never my strongpoint as I did not have enough fingers to count on and people don't seem to approve of you taking your socks off in public for extra digits! LOL

We tend to use things like "Levington Tomorite" for cacti, a tomato fertiliser in the UK originally made by Fisons before they were taken over.

Looking at the ingredients it says:-

Low nitrogen fertiliser 4-3-8

Nitrogen (N) total 4%. Ureic nitrogen 2.1%
Phosphorus (P) soluble in water 1.3%. Phosphorus pentoxide (P2O5) soluble in neutral ammonium citrate and water 3% (1.3%P)
Potassium (K) soluble in water 6.6%. Potassium oxide (K2O) soluble in water 8% (6.6%K)

Dilute 20ml in 4.5 litres (1gallon) of water (I use it half that strength for cacti)

How does that compare with your ideal formula quoted above. If not what should I add to it or dilute it too?

Dave: If I could jump in here for Steve. I just Googled your Tomorite so I could read the label myself. It is labeled in two ways. The elemental way is 4% N-1.3% P-6.6% K, which is the way the ratio Steve got from Mike is stated. Reduce that so N is 1 and you get 1-0.32-1.65 which is also excellent-you can use it as is.

I also had to check your conversion of 1 gallon = 4.5 liters. That is an Imperial gallon. Our US gallon is 3.785 liter per US gallon.

So, 20 ml/4.5 liter is what ppm N? Using a spreadsheet I made up I calculate 178 ppm Nitrogen when using 20 ml fertilizer/4.5 liter water. Half strength of 10 ml comes out to 89 ppm N. Since your fertilizer contains Urea, some of it can be lost as ammonia and you might really have a lower N concentration.

[Steve Johnson]

Hi Steve,

Thank you for the detailed and thought out post...The new product with the appropriate NPK ratio seems to recommend feeding through foliar sprays at the rate of 3 grams per liter of water. Do you know if this is problematic?

You're welcome! And yes, it is problematic because cacti and succulents are CAM plants, as you noted. You can find a good article on the subject at Wikipedia here:

https://en.wikipedia.org/wiki/Crassulac ... metabolism

Since their stomata open only at night, cacti take all water and nutrients up through their roots. Long story short, foliar feeding is impossible.

Would a soilless mix tolerate very infrequent watering? I shall try your pumice test and report back with my findings!.

I'd hesitate to give you an answer unless you can be more specific about what you mean by "very infrequent". Here's the thing about pumice -- appearances can be deceiving, and apparently bone-dry pumice retains moisture longer than you might imagine. That's why a wet weight-to-dry weight test using a scale is the most accurate way to know when the pumice is truly dry as you calculate the number of days. Cactus roots are remarkably efficient about taking up small amounts of moisture down in the pot, hence the reason why the mix should be bone dry at the bottom before it's time to water again. Your findings should give us an answer to your question. By the way, I think you may be able to grow cacti year-round -- something we can't do in SoCal.

[Narubest]

Hi Jerry,
Thank you for your response. It seems that I am in luck! The P portion is indeed P2O5. I have ordered a 500 gram potion of the product last night!. This is the product in question, It has a western name but I am not sure whether it is a product on the western market. Upon searching the internet to find out more about the product I learnt that the instructions are to mix 3 grams or 1 teaspoon in 1 liter of water and apply as a foliar spray every 7 days. I would think that apply chemical fertilizers to the skin of our cacti would cause build up of some sort and perhaps burn the plant over time. Am I wrong to assume that? Have you heard of feeding cacti only through foliar feeding?

Narubest

Hi Narubest

You did not say if the Potassium (K) is reported as K20. I'm going to assume it is, but I am only going to calculate NItrogen. I am also going to assume you are using a dry granular product since the label says to use 3 grams per liter. We don't usually weigh liquids!!

16% N in your fertilizer = 160,000 mg N per Kilogram fertilizer. Which is also 160 mg N per gram fertilizer. Your label says to dissolve 3 grams fertilizer in one liter water. That comes out to 480 mg N per liter of fertilizer to apply to your cacti. That is 480 ppm N!!! Way too high!!!

To get to a more reasonable 50 ppm N, you should dissolve 0.3 grams fertilizer in a liter to fertilize your cacti by watering your pots. I do let my fertilizer water wash over my cacti, but I don't grow any with a bloom on the surface that might be damaged and I am only using 25 ppm N. I also water in between fertilizing with plain water which rinses off the plants.

Thanks for your response Jerry,

the Potassium is indeed K2O and is a dry granular soluble product. I will try feeding my plants at your recommended rate and report back!. Thank you for this PPM maths, I am rather uneducated regarding PPM

[Steve Johnson]

Steve,
May I ask what the rationale is behind the relatively higher N and lower P? The ratios are contrary to peer-reviewed literature I have read.

Comparing nonxeric plants to xeric plants (such as cacti and succulents) is like comparing apples to dump trucks. My guess is that the peer-reviewed studies you're reading applies to nonxeric plants. Mike is by no means the only experienced cactus and succulent grower who knows that P should be lower than N -- P higher than N inhibits flowering, and it causes other long-term growing problems. Best if we learn from experience, not what we read in the literature.

[Narubest]

Hi Steve,

Thank you for the detailed and thought out post...The new product with the appropriate NPK ratio seems to recommend feeding through foliar sprays at the rate of 3 grams per liter of water. Do you know if this is problematic?

You're welcome! And yes, it is problematic because cacti and succulents are CAM plants, as you noted. You can find a good article on the subject at Wikipedia here:

https://en.wikipedia.org/wiki/Crassulac ... metabolism

Since their stomata open only at night, cacti take all water and nutrients up through their roots. Long story short, foliar feeding is impossible.

Would a soilless mix tolerate very infrequent watering? I shall try your pumice test and report back with my findings!.

I'd hesitate to give you an answer unless you can be more specific about what you mean by "very infrequent". Here's the thing about pumice -- appearances can be deceiving, and apparently bone-dry pumice retains moisture longer than you might imagine. That's why a wet weight-to-dry weight test using a scale is the most accurate way to know when the pumice is truly dry as you calculate the number of days. Cactus roots are remarkably efficient about taking up small amounts of moisture down in the pot, hence the reason why the mix should be bone dry at the bottom before it's time to water again. Your findings should give us an answer to your question. By the way, I think you may be able to grow cacti year-round -- something we can't do in SoCal.

Thank you for your response Steve.

Regarding foliar, I did so some reading regarding CAM (not too in detail) but I had the idea that if I were to foliar late at night from 11pm to 1 am. Then perhaps their stomata would be open to update nutrients from a foliar feed?. I will use this new product diluted in water and watered to the roots.

Infrequent watering to me is at watering every two weeks or so, I am not crazy about growth rate but more concerned with growing a plant that is more true to form (unlike some very obese thai lophophoras we see for sale) I will try your test but right now we are in our rain season in Chiang Mai, Thailand. From early june to september every year we get majority cloudy days with lots of rain and humidity. My first year collecting without rain protection, I lost a lot of my trichocereus bridgesii. I believe that our temperatures are appropriate for year round growth however the rain season presents some issue. My current method to combat the rain season with success is to simply not water my plants at all. The issue is that some days we random bright sunny day and the temperature can spike very high. so far I have not seem any negative effects but I fear a 3 month drought with a day of searing sun would surely kill all my plants.

[Narubest]

Steve,
May I ask what the rationale is behind the relatively higher N and lower P? The ratios are contrary to peer-reviewed literature I have read.

Narubest,
I do not know why cacti placed in full indirect sun will etiolate... it is strange. Without seeing pictures I can only suggest using a lux meter to measure the light your cacti are getting. It may be that they receiving less light that you think. I personally do not see how soil mixes, a balanced slow-release, or reasonable amounts of cal/mag will lead to cause etiolation. I live in the tropics, use peat in my mediums, fertilise heavily, only use LEDs and my columnars are not etiolating.

May I suggest that you also reach out to Thai nurseries for advice more specific to your environment? A lot of our experiences come from growing cacti in the Western hemisphere which may not be applicable to you. Uncle chorn and weerapat wiriyajarn were very accommodating once I made a few purchases.

H

Hello Hudson,

I will follow your advice and purchase a lux meter. Do you happen to know what the appropriate figures are for light levels. I can read thai but cannot type thai very well. Perhaps I can try physically show up and see if anyone is willing to talk to me.

[HudsonLH]

Steve,
May I ask what the rationale is behind the relatively higher N and lower P? The ratios are contrary to peer-reviewed literature I have read.

Comparing nonxeric plants to xeric plants (such as cacti and succulents) is like comparing apples to dump trucks. My guess is that the peer-reviewed studies you're reading applies to nonxeric plants. Mike is by no means the only experienced cactus and succulent grower who knows that P should be lower than N -- P higher than N inhibits flowering, and it causes other long-term growing problems. Best if we learn from experience, not what we read in the literature.

Steve,

Thanks for the response. From what I understand, low N, higher P and K is how you should fertilise cacti. These ratios are from cactaceae literature. I can perhaps provide links when I am back from work. Low N, higher P/K are also the ratios adopted by Japanese, Thai, and Malaysian commercial nurseries. Do you have other evidence backing your claim? It will be an interesting read.

H

[Steve Johnson]

Regarding foliar, I did so some reading regarding CAM (not too in detail) but I had the idea that if I were to foliar late at night from 11pm to 1 am. Then perhaps their stomata would be open to update nutrients from a folia feed?.

As I said, cacti take all water and nutrients up through the roots. A foliar feed won't do anything.

Infrequent watering to me is at watering every two weeks or so, I am not crazy about growth rate but more concerned with growing a plant that is more true to form (unlike some very obese thai lophophoras we see for sale)...The issue is that some days we random bright sunny day and the temperature can spike very high. so far I have not seem any negative effects but I fear a 3 month drought with a day of searing sun would surely kill all my plants.

I water most of my cacti every 2 weeks in Spring and Summer, so I think that'll be fine for you. As to the sun problem, would it be possible for you to rig up a shade cloth enclosure? I have the entire collection under 40% shade cloth, and it's a great way to prevent sunscorch if you can't shade your plants during the hottest time of the day.

[HudsonLH]

Steve,
May I ask what the rationale is behind the relatively higher N and lower P? The ratios are contrary to peer-reviewed literature I have read.

Narubest,
I do not know why cacti placed in full indirect sun will etiolate... it is strange. Without seeing pictures I can only suggest using a lux meter to measure the light your cacti are getting. It may be that they receiving less light that you think. I personally do not see how soil mixes, a balanced slow-release, or reasonable amounts of cal/mag will lead to cause etiolation. I live in the tropics, use peat in my mediums, fertilise heavily, only use LEDs and my columnars are not etiolating.

May I suggest that you also reach out to Thai nurseries for advice more specific to your environment? A lot of our experiences come from growing cacti in the Western hemisphere which may not be applicable to you. Uncle chorn and weerapat wiriyajarn were very accommodating once I made a few purchases.

H

Hello Hudson,

I will follow your advice and purchase a lux meter. Do you happen to know what the appropriate figures are for light levels. I can read thai but cannot type thai very well. Perhaps I can try physically show up and see if anyone is willing to talk to me.

Narubest,

It is very dependent on genera. Gymnocalyciums tolerate up to 20k lux (though many will get sunburn at this level without build up) while astrophytums and echinopsis can go up to 35k. I keep my cacti with heavily spination (e.g., many turbicarpus vars) in near 50k lux without signs of sunburn. Both chorn and wiriyajarn keep fantastic columnars and will likely be able to provide valuable insight. I am not sure if they will entertain you without prior purchases though

H

[Steve Johnson]

Do you have other evidence backing your claim? It will be an interesting read.

From my Member Blogs thread, start here and you'll have a lot (and I mean a lot) to go through:

http://www.cactiguide.com/forum/viewtop ... 10#p365647

The starting point I'm giving you here begins my 2019 end-of-summer review. The only evidence I have comes from my own experience, so you can decide for yourself whether or not I'm able to back the claim.

By the way, commercial nurseries are interesting in growing salable plants. Their growing practices may be (and probably are) different from the practices being followed by collectors who are interested in the long-term health of their plants.

[Narubest]

Regarding foliar, I did so some reading regarding CAM (not too in detail) but I had the idea that if I were to foliar late at night from 11pm to 1 am. Then perhaps their stomata would be open to update nutrients from a folia feed?.

As I said, cacti take all water and nutrients up through the roots. A foliar feed won't do anything.

Infrequent watering to me is at watering every two weeks or so, I am not crazy about growth rate but more concerned with growing a plant that is more true to form (unlike some very obese thai lophophoras we see for sale)...The issue is that some days we random bright sunny day and the temperature can spike very high. so far I have not seem any negative effects but I fear a 3 month drought with a day of searing sun would surely kill all my plants.

I water most of my cacti every 2 weeks in Spring and Summer, so I think that'll be fine for you. As to the sun problem, would it be possible for you to rig up a shade cloth enclosure? I have the entire collection under 40% shade cloth, and it's a great way to prevent sunscorch if you can't shade your plants during the hottest time of the day.

I use a 50 percent shade cloth enclosure right now, its about 3 meters high and arched, the arch potion has shade cloth but the sides do not have the shade cloth. Should I be using the shade cloth on the west side aswell as the top

[Steve Johnson]

I use a 50 percent shade cloth enclosure right now, its about 3 meters high and arched, the arch potion has shade cloth but the sides do not have the shade cloth. Should I be using the shade cloth on the west side aswell as the top

Not a bad idea -- I have my shade cloth enclosure covering the east-, south-, and west-facing sides of the collection. Early morning sun coming from the east can be pretty intense when it's really hot, although I don't know if that's your experience in Thailand.