When you are fertilizing orchids, you need to remember that most orchids grow above the ground (usually attached to trees) and that they are fed and watered by rain runoff containing very diluted nutrients.

Because of their natural habitat, most orchids are not heavy feeders.

The old saying, "weakly, weekly" is a good rule of thumb (fertilize using a weak solution one day per week) when fertilizing orchids.

What kind of fertilizer should I use?
The correct type of fertilizer to use on your orchids is very important! Avoid using general purpose fertilizers designed for lawns and gardens.

All fertilizers consist if three main ingredients:

nitrogen (N) which promotes general plant growth

phosphorus (P) which promotes flowering

potassium (K) which promotes strong roots.

The ingredients are mixed in various combinations because plants have different needs.
The combinations are indicated by a three number code:

The first number is the percent of nitrogen (N)

The second number is the percent of phosphorus (P)

The third number is the percent of potassium (K)

A good balanced fertilizer like 7-9-5 (N-P-K) is good for all mediums you might be using to grow your orchids in. For years, it was thought that bark robbed nitrogen from the orchids and that a high nitrogen fertilizer such as 30-10-10 was needed. However, recent research in this area has proved this to be untrue.

You may notice that when the three numbers are added up, they don't total 100%.
The figures represent ratios, not percentages of the ingredients present in the mixtures.

To help promote flowering, you can use a special type of fertilizer called "blossom boosters."
This is used just prior to bud formation and is a 3-12-6 formula.

Do not use fertilizer containing urea on any orchid. Urea requires breakdown by soil microbes. A toxic salt build up can occur that can burn tender roots.

Fertilizers are distributed in many forms, granules, liquid, spikes, etc.
I recommend you use a water soluble (granules that are dissolved in water or liquids that are diluted with water prior to use) type orchid fertilizer which should be available in most garden centers.

How much fertilizer should I use?
The recommended dosage varies according to the manufacturer but is usually only 1/4 or 1/2 teaspoon per gallon of water. Follow the manufacturer's directions and remember, "weakly" is better! Less is better than more!

How often do I fertilize?
Some orchidists recommend fertilizing every week and others recommend every other week. I personally water every week and add fertilizer to my water every other week

How do I know if I am not fertilizing enough?
Smaller than normal growth or yellowish leaves is an indication of possible insufficient fertilizer. Most of the media used to pot orchids offer no nutrition to the plant.

Organic media (orchid bark and Sphagnum moss) will release small amounts of nutrients as they decompose.

How can I tell if I am over-fertilizing?
A salt buildup (which looks like white crusts on the media and around the pot) is a sign of overfeeding. The roots of your orchid will turn black if they come into contact with this salt buildup and if the buildup continues, the plant could die.

Excessive algal growth on the media and or in areas on benches or on the floor beneath orchids (originating from the runoff after watering) may indicate that the amount of fertilizer you are using is too much.

When the tips of the leaves die, it could also be an indication of too much or chemically unbalanced fertilizer.

To prevent this condition, you should practice an alternating watering and fertilizing routine.

Give fertilizer to your orchid at every other watering. This will allow the fresh water to flush your orchid of any leftover fertilizer, salts, and minerals that may have built up in the pot.

Learning to use a conductivity meter to use the properly diluted fertilizer solutions will pay dividents!

What should I do if I have been over fertilizing?
Leach out the medium, preferably with soft water (rainwater, deionized water).

Depending on the habit and size of the orchid, the simplest method is to immerse the whole plant in a large volume of water for several hours - then let it dy to the normal moisture level.
The process can be repeated if necessary, especially if the potting mix is rich in highly absorbent ingredients like peat or coconut husk chips are.

If visible salt accumulation occurred, leaching cannot help, because the salt accumulations in commonly used orchid potting mixes are poorly soluble or even absolutely insoluble in water.

In such cases the best thing to do is to re-pot your orchid in a new (sterilized) pot with new media.

Before placing your orchid into its new pot, flush the salt from the roots and around the growths with running water. Reduce the amount of fertilizer to the recommenced amounts.

And remeber the time-proven wisdom: prevention is better than cure ...

Orchid Fertilizing Tips
Water your orchid with fresh lukewarm water (never cold water) weekly.
Add fertilizer to the water every other week.

If the tips of your plants become dry and start to turn black, it could be a sign of over fertilizing. Be sure you are flushing the excess fertilizer out of your media between feedings.

Don't fertilize a sick plant.

Don't add extra fertilizer to your plants to help them grow. This will not help.

Make sure your water is luke warm, don't use cold water.

Pour the fertilizer thrugh the pot or over the media just like you were watering.

DO NOT "catch" the fertilizer runoff and then use it on another plant.
This practice will spread diseases.

Learn what kind of an orchid you have. Some have "rest periods" and do not require feeding during this time.