How much osmocote?
 

How much osmocote are you using for your catasetums? Anyone have a volumetric measurement? Like 1 TBSP, per 500 mL of media?

I have to admit that I dispense the time release fertilizer (I use Nutircote, pretty much the same) the way I add salt when cooking... A big pinch in a small pot (maybe a teaspoon), what fits in the palm of my hand for a big pot (maybe a tablespoon). Not precise, I just go for what seems like a reasonable top-dressing.

I do the same as Roberta.

How much is going to depend upon the formula, and to a lesser degree, on the release profile.

I also eyeball it, with similar amounts described by Roberta.

ah ok, looks like everyone is pretty much just eyeballing it, and adding it onto the top of the media. No one is mixing it into the media?

Also, it seems osmocote is heat activated, and Nutircote is more time released? So in the icy north of NJ, maybe Nutircote is a better option?

Ray, what formulation would you recommend for carasetums, which are very high-demand for nutrients? This past season I was using a ridiculous amount of the K-lite fertilizer....

Nah, no need! If the fertilizer starts at the top, it should have more residence time in the pot (and therefore have more chance of being used) if it has a longer way to travel before it gets dumped out the bottom.

I recall reading Ray's (and others) comments about osmocote dumping its nutrients in a short period in hot weather. I use nutricote here in Texas with great success.

All "controlled release" fertilizers are controlled by temperature. The fertilizer powders are encapsulated in a porous polymer coating that has a known thermal expansion. As the coating gets warmer and expands, the pore size enlarges, allowing more water in and fertilizer solution to escape.

Manufacturers use different polymers based upon the intended application. For example, the stuff I use on my shrubs, annuals and herbs here in southeastern NC has the following profile:

https://firstrays.com/wp-content/upl...ife-300x50.jpg

When I was in PA, where the ground is cooler, I used one that had a 5-6 month expected life span at 70°.

Also keep in mind that the published "longevity" numbers are assumed to be at a constant moisture content.

People who see Osmocote as "dumping" too much nutrition are probably just using the wrong one, but if they water more often - due to hot weather, or whatever - that also accelerates the extraction (dumping) rate.

I don't grow them, so cannot recommend, but generally, I think K-Lite's formula is appropriate for most orchids.

Remember that it is the mass of applied nutrients that is important, so whether you use a mix-and-apply formula, or a slow release one, the amount (of nitrogen, particularly) applied should be the same.

I don't know what you consider to be "a ridiculous amount", but if you water well, flooding the pot, doing so with a fertilizer solution and with plain water on pots containing slow-release fertilizers, the losses to drainage should be similar.

I don't use it. I just water with full strength fertilizer and whatever nitrates come with rain water. It obviously doesn't hurt the plant, but I think it is over kill if using full strength fertilizer and nuticote/osmocote. Yes, these plants love fertilizer. However, I feel there is an overabundance just using full strength. It is more of an issue on keeping fertilizer cost down for me.

I also only repot every 2 to 3 years in PET. I don't feel like the osmocot/nutricote is helpful in the second year.

Small handful on top of the media on any plant I don’t water often. I have a lot of rain-maintained plants so they don’t get the super soup as often. They have the time release just to make sure they aren’t deficient