A cool down period is a night time temperature of 10 to 15 degrees cooler than what they receive during the day.
The length of the cool down is usually two to three weeks in the fall. If you are like me, you will give this to them without trying. I wait until the last minute to light those furnaces in the greenhouse.
If you are growing your orchids indoors, you can meet this requirement for most orchids by simply turning your heat down at to 55-60 Fahrenheit degrees at night (According to the power company, you should do this anyway to save money).
If you try and grow your orchid at 70 oF degrees day and night, chances are you will get beautiful foliage but no flowers.
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) promotes general plant growth
Phosphorus --(P) promotes flowering
Potassium -- (K) 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 medium 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.
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.
You may notice that when the three numbers are added up, they don't total 100%. The missing percent is composed of inert ingredients.
Fertilizers are distributed in many forms, granules, liquid, spikes, etc. I recommend you use a water soluble orchid fertilizers 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.
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 (bark and 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 over feeding. 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. When the tips of the leaves die, it could also be an indication of too much fertilizer.
To prevent this condition, you should practice a 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.
What should I do if I have been over fertilizing?
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.
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 lukewarm, don't use cold water.
Pour the fertilizer through 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.
Linda's Orchids on CDs 
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: 