Orchids can actually live healthy without fertilizers, if you provide it with proper care, which means sufficient watering, exposing it to enough light and prune it the right way as needed. Fertilizers may be used if you aim to get a well built plant with stronger and healthy roots and more flowers. Since orchids need less fertilizer than any other plants, the use of a fertilizer should be applied with caution. Always bear in mind to use a well-diluted fertilizer mixture when trying to provide additional feeding to your orchid. Over-fertilizing can really harm your orchid.
Three major chemical components of a fertilizer are nitrogen (N), phosphorous (P) and potassium (K= Kalium). Those three components are usually labeled as N-P-K and printed as numbers on a commercial fertilizer label. These numbers represent the percentage of each component. A labeling of 20-20-20 for instance, means that it contains an equal content of 20% each. Other elements that are needed by a plant are calcium, magnesium and sulfur, which can be found in lesser amounts.
As there are many commercial fertilizers with various compositions, you may as well make your own orchid fertilizer using some unused kitchen stuff that may contain N-P-K like eggshells, chicken bones, rice water, tea bags and milk.
Eggshells are viable sources of calcium and potassium and can be used as fertilizer. Don't throw away eggshells, wash and collect them until you get 20 – 25 eggshells. Crush it with a mortar and let it boil in a gallon of water. Let it soak for about 8 hours. Filter out the eggshells and keep the water in a container. You can use it to water your orchids on a weekly basis.
Dried and crushed chicken bones are other good kitchen stuff useful as calcium and potassium source. Again, do not throw away chicken bones, but wash them and spread them out in the sun to dry or dry them in an oven. Crush the dried bones thoroughly and keep it in a jar. Sprinkle the dusty bones onto the potting medium on a monthly basis.
Rice water is a good source of vitamin, vitamin B in particular. What I mean by rice water is the water that is used to wash the rice prior to cooking as well as the water in which the rice is cooked. You can directly use it to water your orchid. But make sure that you cool down the cooked water first.
Tea contains non-toxic organic materials and is rich in nitrogen which is good for your orchids. Hence you can make use of teabags. Just open the teabag and pour the tea onto the potting media once a month.
Milk can be the source of protein, thus provide high content of nitrogen. You can make use of a milk bottle or carton which has just been emptied. Fill it with water and shake it well so that the milk residue will be diluted in the water. Use this to water your orchid.
Fallen oak leaves are naturally a good source for fertilizer. And since they are completely natural, there is no need to worry about the negative effects of chemical fertilizers. Collect dry leaves and put it in a 5 gallon container. Fill it with about 2 gallons of water. The portion should be 1/3 water and 2/3 of the leaves. Get it exposed to sunshine for about a week or until the water shows an ice-tea color. If you couldn't get the ice-tea color after a week, pour it with warm water and let it cool down. You can then use it to water your orchid on a 2-week basis.
Potatoes are another practical source of calcium and potassium. Cut an unpeeled potato into small dices and let it boil for a few minutes. To provide more potassium, you can add fresh banana cuts into the boiling potato mixture and stir it well. Let it cool down and keep the mixture in jar. Add this mixture to the potting media on a 2-week basis.
Last but not least a kitchen stuff to be considered as fertilizer is molasses as a source of potassium. Just take a teaspoon of molasses to be diluted in the water you are going to use for watering your orchid.
Epsom salt is a good source of magnesium.
Well, that concludes some common homemade fertilizers that can be easily made available using some kitchen trash. To us those may be garbage, but to our orchids it is good treat assuming you are not overdoing this fertilizing stuff. So, happy orchid caring!