Fertilising with non-orchid fertilisers

[Neverend]

I'm thinking of using my general fertiliser for my orchids too, after realising that my current orchid fert (Gaviota) is lacking in some trace elements. My Cattleya alliance orchids are showing signs of calcium deficiency, so I think I better act fast.

I'm thinking of using Phostrogen, with a NPK of 14:10:27, calcium:magnesium 2:5. If I use it at half strength would it be safe for my orchids? Can I switch to using this as my only fert for orchids too?

[SaraZ]

i was just at our local orchid growers meeting and they suggested doing just that, using your regular fertilizer. The NPK ratio they talked about was 30:10:10 or 30:10:20 at 1/2t to 1/4t per gallon. They said to look for trace amounts or magnesium and sulfers in the mix. I have not yet tried it but am going to soon. Good luck!

[Neverend]

I just experiment with my B. Little Stars and Iwan. AB today, hopefully it'll show some results :P

[camille1585]

Whenever I use a nez fertilizer on my orchids, I always use Ray's very handy calculator to figure out how much to give.
Fertilizer PPM calculator
Scroll down to the bottom of the page, and type label N of your fertilizer and how much ppm N you wish to give your plants.
For example, let's say you are aiming for 125ppm of N at each watering. Your label N is 14. The result is that you need 0.68 teaspoons/gal of fertilizer to give your plants the right amount.
As for the NPK ratio of your fertilizer, I wonder if it's appropriate for orchids since it is very unbalanced. I don't know what is considered a good ratio for orchids, but I always thought it was better to a have a balanced fertilizer. Maybe more experienced members will chime in on this!

[orchids3]

If you ask many large commercial growers what they use you will find that most use commercial fertilizers. Some even mix their own. Right now I am using Floriculture 17-5-17 Cal Mag which is 4% Ca and 1% magnesium. Adjust your mix so you get 125 PPM (Parts Per Million) Nitrigen in the summer and less (according to wheather your plants are activily growing) in the winter. Make sure that all micro nutrients are represented. Choose fertilizers that have the Nitrogen in the Nitrate or ammonia form (Some say urea's are OK but I avoid it) Fertilizer salesmen are like Fish lure salesmen in that they sell what they can get money for not whats good for the fish or in this case plants.
If you dont have time to really study fertilizer then stick with the so called orchid fertilizer, some of it is ok but even fertilizers marked for orchids are not always good.

[David Morris]

When Fertilizing with Calcium one has to keep in mind that Chemicals such as Calcium Nitrate, Magensium sulfate are incompatable with traditional fertilzer. What we did when I worked for Cebeco was mix the different chemicals into 2 different vats which than combined just before going in to the watering lines. What I do at my orchid Nursery is alternating feedings. 1 tsp of each per gallon of Epson salts (Magnesium sulfate), and Calcium nitrate inbetween regular fertilizing shoul do the trick

[orchids3]

Camille.
Most of what you say is ok with me but what do you mean by a balanced fertilizer. According to test results published by Michigan State Univerisity - fertilizers should have a low Phosphorus level. I use 17-5-17.
The 5 is the Phosphorus. More phosphorus is not only
unnecessary but is harmful to the enviornment. It is my understanding that hight phosphorus may actually be banned some time in the future.

[camille1585]

Originally Posted by orchids3

Camille.
Most of what you say is ok with me but what do you mean by a balanced fertilizer. According to test results published by Michigan State Univerisity - fertilizers should have a low Phosphorus level. I use 17-5-17.
The 5 is the Phosphorus. More phosphorus is not only
unnecessary but is harmful to the enviornment. It is my understanding that hight phosphorus may actually be banned some time in the future.

I agree with you on that. I have heard about MSU's findings, and wish their fertilizer were available here. But it isn't (and I havn't found anything remotely similar), so I use what I can find. What I meant by balanced is something like a 10-10-10 for example, instead of something where one element is in much greater quantities than another. Obviously 17-5-17 seems like the best, but am I wrong in assuming that balanced is good too?

[David Morris]

Hum, so is there a study that shows that using a fertilizer such as 20-20-20 is therefore bad for the environment? As a reformed research horticulture person I always question what we are being told (how much salt we should have for instance). Anyway Phosphorus is neccesary. It is a macro element . How much could be argued, but without it neither you nor your orchids will survive.

[orchids3]

David,
I cant lay my hand on the paper that published that but a doctor I correspond with in Australia has indicated that the cancer rates in Australia increased in direct proportion to the use of phosphate fertilizers and is also credited with the destruction of ocean plant life. If high levels of phosphorus is not necessary - why use it? Will continue to look for where I read all that and post it if I find it. Note that I understant that phosphorus is necessary but not in high percentage. The old belief that high phosphorus levels promoted blooming (High phosphorus fertilizer is often called bloom buster) is not true according to the MSU experiments. I believe I found some of the information in Dr Argo's papers about the so called MSU fertilizer was on First Rays website. Have dropped the use of high phosphorus myself and found that I agree with Dr Argo.
Read the five articles at Plant Nutrition also excellent for understand fertilizer is
PDF Articles. The last link involves Paphs but the part about mineral nutrients, and limestone supplements is packed with information about fertilizer in general and both are available on the internet.