In nature, orchids grow on rocks and trees. They get by on a slim diet of organic matter that collects at their roots from the wind and rain. This can be anything from decaying tree bark to bird droppings.
Live bacteria, enzymes, and microbes break down this organic matter into a form the plant can use.
This process is almost impossible growing at home with potted plants. Potting materials are sterilized, killing the bacteria, enzymes, and microbes needed to transform organic matter into a form your plants can use. So, potted plants rely on you, the grower, to provide the nutritional elements.
Don't confuse "plant food" with "plant fertilizer or "plant nutrients". Plants manufacture their own "food" using a process called photosynthesis. With the power of the sun, they combine air, light, and water to make carbohydrates, which is the real food they use for growth.
"Plant ferilizer (or nutrients)", on the other hand, are the mineral elements collected by the roots to enhance photosynthesis. Plant fertilizer (or nutrients) cannot compensate for the lack of real food plants need for growth (air, light, and water).
So, before you give your plants that extra dose of nutrients (or fertilizer), make sure they're getting the the right amount of "real food" they need for growth - air, light, and water. Without them your choice of nutrients (fertilizer) won't matter.
Nitrogen is the primary ingredient in all fertilizers. Urea is an inexpensive form of nitrogen.
Orchids can't use urea until it is broken down by enzymes or bacteria. That's great for outside plants, but sterilized potting mixes don't contain the enzymes needed to convert urea into something the plant can use.
Unused urea turns to salt and actually harms the plant's roots because orchid roots can't tolerate salt. If you're using a plant food that has urea on the label you might actually be harming your plants! Look for nitrate nitrogen or ammoniacal nitrogen on the label, not urea.
Correct nitrogen source
Never use urea!
All plants need 16 essential elements for optimum growth. Look on the back panel of the package - are there 16 elements in your fertilizer?
To lower costs, most fertilizers skip elements - leaving your plants to rely on the potting material to provide what's missing. How do you know what your plants are really getting with this hit-or-miss approach?
Hydroponics doesn't rely on the potting mix for any nutritional value. That means hydroponic fertilizers always have all 16 nutritional elements plants need, in a form they can absorb immediately.
In nature, houseplants live on the forest floor where their roots grow in a combination of soil, decaying leaves, and animal droppings. They choose their nutrients from an "all you can eat" smorgasboard of mineral elements.
Orchids, on the other hand absorb their nutrients high up in the trees. The water and nutrients they get can be sparse but they're cleaner and more pure than the water and nutrients houseplants find on the forest floor.
Orchids are naturally more finicky than houseplants about what fertilizer (or nutrients) they get.
A good nutrition program for orchids requires a quality fertilizer that has all the elements plants need for growth - in a form the plant can use immediately - without complex biology.
Don't think there's a difference in fertilizers? Ask your plants! They feel the difference immediately.
More on plant nutrition -
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