In general which Orchids are heavy or light feeders?

[ipv6ready]

Hi all, another simple questions but I am a little lost and would like some guidance.

I have read and learned a lot from this forum especially about weakly, weekly feeding methodology. But I want to feed every watering and I want to get it closely to ideal as possible to each group of orchids I have.

I have a varied collections of Orchids and have been feeding them all the same amount of fert.

Having just checked First Rays sites it seems I have been over feeding all my orchids way to much. though with no sign of damage

According to Ray's TDS calculator I am feeding my plants 450ppm N every feeding . Which in Sydney Australia is about every three days.

All are doing well but I realised there are things I don't know enough about orchids so I wanted to ask before I do any long term damage.

I have read Ray's reasoning for 125ppm, but I don't have as many plants as Ray so I can take the time to tailor my feeding accordingly for the each alliance.


My collections is

Aussie Dendrobiums
Dendrobium Nobile
Oncidium Alliance
Phals
Cyms

So what are heavy, medium and light feeders? Of course I will take dormancy into account at relevant times but in general, how much more or less?

For example, I read that Phals as light feeders so would I feed at 125ppm and does this mean heavy feeders should be fed 200ppm, 250ppm, 300ppm or 400pmm or some other amount?

Thank you so much in advance.

[Daemos]

I feed any type of plant according to an oldskool principle. Too much is bad and just a little is always good. For example if the bottle says 30 ml in 1 liter. I use half the amount. I use the prescribed amount when the plant is spiking and go back to half when it is done speed growing. I repot the heavy feeders every year and the ones that don't need much once in the 2-3 years. Phals don't need anything (I treath them just like my cacti) for the others I don't know but the oldskool rule works for me on any plant including orchids. Hope this will help you in advance.

[Ray]

I think you will ultimately kill your plants by poisoning the roots if you feed 450 ppm N at every feeding. Good thing you don't grow phrags, or they would likely already be gone.

If the conditions are such that your potting medium dries out that quickly, you'll have a pot full of stalagmites in no time.

You have to understand that the level of feeding you want to do is a combination of concentration and frequency. If you water that frequently, you will want to cut the concentration significantly.

Of the plants you listed, the phals are the least hungry. Dr. Yin-Tung Wang of Texas A&M University found that optimal growth in a bark-based medium was at 200-250 ppm N, but that was fed once a week, with clear water in between. (If you feed twice per week with no clear-water-flushing, as I do with S/H culture, that translates well to the 125 ppm N I recommend.)

The cymbidiums are likely your heaviest feeders - I'd go to 200 ppm N at most - but only when actively putting on vegetative growth. I would go so far to say that any sympodial plant will take advantage of the higher feeding level only while in active growth, and in the case of the nobile den, if you feed it at all during later fall and winter, you'll not see any flowers at all.

You might want to read this: Feeding by Mass