Ideal Concentration (PPM) for Foliar Fertilizing Every 15 days or every month
 

Hello everyone, happy growing

I grow semi terrestrial (Anguloas, Cymbidiums, PHrags and Paphs and maybe Catleya or Dendrobium), however, I don't have much time to fertilize every week.

I fertilize with slow release, but I want to add a plus every month or 15 days, what concentration (PPM) of Foliar Fertilizer 20-20-20 could I use.

(Of course, I know that my idea is contrary to the “fertilize little, but constant” that is the must be).

Can you help me? D:

Most orchids don't take up fertilizer through the leaves. Some of the genera you mentioned have very thin leaves, but I don't know whether anybody has studied using foliar feeding on them.

Your slow-release fertilizer should be everything you need if you use enough. If you want to fertilize more, water the plants with a fertilizer - water mixture.

The reason that foliar feeding is rather useless on orchids is that they tend to have a water-repellant cuticle on the top side of their leaves.(For epiphytes - which most of these are - it's a way to conserve water when the rain stops) So any fertilizer on the leaves just rolls off, may end up in the medium where it is useful. Far more efficient to put it on the medium in the first place. Orchids only take in meaningful amounts of fertilizer (and water for that matter) through their roots. Of the orchids listed, really only Cymbidiums are heavy feeders since they grow fast and large (and the time release fert will take care of that) The others really don't need much because they grow slowly.

I would stick to the slow release.