| Be careful... most fertilizers are pretty much the same, but not all of them.
Many fertilizers that are intended for outdoor plants and gardens don't contain the full spectrum of micro-nutrients that are needed for growing healthy orchids, especially if you're growing in an non-organic medium (like S/H), or a nutrient poor medium like CHC, etc. Most of the fertilizers out there now DO contain all of the necessary micronutrients, and some of the common garden variety fertilizers are much cheaper than the orchid ones, so it's worth checking labels.
Also, depending on what you grow, you might want a fertilizer that has extra calcium and magnesium. A lot of Paph growers will add epsom salts instead of getting a Cal/Mag fertilizer, and also add a calcium suppliment to the potting medium like oyster shell, etc (also to buffer the pH).
Finally, I think that a balanced fertilizer is good for general use on most orchids. Generally speaking, plants will take in as much of the nutrients as they need and leave the rest, so a 20-20-20 will have the same effect as a 20-10-20 if your plant only needs 13-9-12. However, for plants that are sensitive to water quality, you might consider using an MSU formula (my tap water formula is 17-9-18) just to reduce the risk of burning your plants' roots.
- Matthew Gore  |