Orchid plants require repotting for two main factors: when potting media breaks down or decomposes and/or plant is getting too big for its present pot or planter.
Re-potting with a fresh potting mix will do if the case is potting media breaking down.
In the case, plant is getting too big for its present pot, a slightly larger pot is required along with fresh potting medium.
The thumb rule for selecting a larger pot for re-potting is, the new pot should be only 1-1.5" larger than the present one.
I'm too lazy. Why can't I just get a big pot and allow my orchid to grow in it for years? Isn't that easier?
Epiphytic orchids in nature are found growing with their roots exposed to the various elements.
They are fertilized by bird droppings and washed by the rain. The old bark is stripped off and replaced with new bark and they are in a symbiotic relationship with various other living organisms in their environment.
In effect, they grow best in a dynamic environment compared to the static environment in a pot.
Beyond 2-3 years, this static environment in the pot can become intolerable to the plant due to the buildup of toxic fertilizer residue, extremes in pH, decaying roots as well as decaying soggy media. This can only be set right by repotting.
I have a lot of algae and moss growth on my orchid roots. How can this be controlled?
Algae and mosses grow in an acidic and moist environment. Orchids like to dry out between waterings while algae and mosses like to be constantly wet all the time.
Whenever you water your orchids remember to water them thoroughly once or twice a day as climatic conditions demand rather than several halfhearted mistings spaced out several times during the day.
If this doesn't solve your problem especially during the monsoons, then you can top dress with Dolomite or Calcium Carbonate(Oyster Shell). Remember that Oyster Shell generates a lot of heat and is not to be used during hot weather.
This raises the pH making it impossible for the algae and mosses to grow. Never use bleaching powder to kill algae as it can also be detrimental to your orchids.
I've visited a lot of orchid sites and each one has something to contradict what I've previously learned. How do I know if I'm reading the right thing?
You must remember that what works for you might not work for another person, for the simple reason that there are various parameters involved when it comes to growing orchids successfully.
Different orchids come from different regions of the world and have evolved to adjust to that particular climate. There are orchids that come from regions where it rains most of the year and there are others that will not bloom unless there is a remarkable dip in temperature.
Before buying your orchid, read well about their requirements and see if it will be possible for you to provide similar conditions. Talk to our Orchidists at Orchid Tree and gradually you'll learn how to grow your orchids to the best.