I would like to share my technique of re-potting a Phalaenopsis orchid with the novice phalaenopsis growers, and with some of the more experienced ones who may find it interesting.
I have been growing phalaenopsis for eight years successfully. I use to grow them outdoors under shade cloth, when I was living in a tropical environment, and since I have moved to a more temperate area, I am growing them indoors on a window sill.
My potting technique hasnít changed much and I always get good results and healthy roots growing on my orchids; at times wandering a little bit too much around the pots...
Healthy Roots growing on my Phalaenopsis
The plant to be re-potted
Today Iím re-potting a phalaenopsis hybrid that I purchased a few months ago.
I normally re-pot straight away if I see signs of root rot or the plant is not looking healthy. I feel more confident with the watering when they are in my preferred mix, and with experience I can tell when they need to be watered. Otherwise the best time for re-potting is in spring just after the plant finishes flowering.
The plant still looks healthy, but the roots inside the pot do not seem to be growing much compared to my other phals; I think itís time to give it a new start and at the same time Iím desperate to re-pot!
What to use?
I use the following ingredients for my re-potting:
For the potting mix I use 1 part pine bark, 1 part horticultural charcoal, and 1 part scoria. I find this mix ideal in terms of moisture retention, and air movement inside the pot. It has a relatively quick drying rate, which I found excellent to avoid root rot. I prefer my orchids on the dry side than being too wet for a long time.
From left to right: Pine bark, Scoria, and Horticultural charcoal
The pine bark should be of a coarse grade, and soaked in water before use, the charcoal should be of similar grade. Scoria can be substituted by natural stones like granite or any non polished stones, pebbles, or clay pellets. I find scoria a good addition to orchid potting mix as it remains sterile and does not break down, it holds some moisture, and provides good adherence for the roots. It also adds some color to the mix, which is good to cheer up the mood when re-potting!
I use Styrofoam nuggets, or polystyrene from packaging cut into pieces as a drainage material at the bottom of the pot. This assures that the mix above remains moist not wet, as the water drains more easily and does not accumulate in the mix.
Sphagnum moss is scattered on top of the mix mainly and around the roots to raise the humidity at the surface, as this area tends to dry up quicker.
Sphagnum moss and small pieces of polystyrene ready for use
Which Pot to use?
There are two choices of pot for phals: black plastic squat pots, and clear plastic pots.
Both pots are well adapted for phalaenopsis orchids, but Iíve noted that the medium in clear plastic pots tend to dry a little bit faster than that in the squat pot, probably because of the lateral slots; so the final choice might depend on the type of environment/humidity level, the size of the plant and/or pot availability.
First remove the plant from the pot by squeezing the sides of the pot with one hand and pulling the plant with another. Then tear all potting mix and inspect the roots. I am surprised to find that there are actually not a lot of roots growing in the pot, and some of them are rotten; this is probably due to the fact that the old potting mix has broken down too much and has turned sour. I'm quite happy that I've decided to re-pot it now.
Cut all dead, decaying, or broken roots with a disinfected secateurs or pair of scissors. Only leave live roots on the plant, greenish if wet or grey/white when dry. Donít be afraid to cut as much as possible, as new roots will grow much faster when the plant is clean and in a healthy medium.
I then rinse the plant and roots with water to get rid of the old potting residue. I donít use any fungicide as I donít normally have fungal problems, but one may do so if they are prone to root rot.
Prepare the pot
First put a layer, about an inch, of polystyrene at the bottom of the pot, then some of the mixture. Place the plant in the middle of the pot and wobble it with a little bit of pressure to get all the roots in. Roots which were growing outside before re-potting are left out as they are used to grow in the air.
Add the mix
Add more mix in the pot and around the roots, while holding the plant in its desired position. The base of the oldest leaf should sit just above the potting mix, below the pot rim.
Sprinkle a few pieces of sphagnum moss around the roots, this will keep the level of humidity high close to the plant, and make the pot look nice at the same time.
I water my newly potted orchid the same day, as this gives me instant satisfaction and my phals seem to like it.
I then wipe all leaves with a tissue or cotton pad and avoid any water sitting in the crown of the leaves.
The phalaenopsis orchid after re-potting
I write the date of re-potting on the existing tag with a permanent marker, and stick it in the new pot. I will leave the plant undisturbed on a tray of pebbles with some water at the bottom for at leas two weeks without watering. New roots should start to develop after three weeks to one month after re-potting.
Given the low decomposition rate of this mix, the plant would not need re-potting for two years, unless itís growing excessively fast and too big for the size of the pot, then I will re-pot it the following year.
Next time the phalaenopsis sends its flower spike, Iíll understand it is its way of saying ĎThank youí
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