Repotting an orchid is really quite simple. Photo: www.t-online.de
Like any houseplant, orchids need to be repotted occasionally, especially when their potting mix has started to decompose (notably, the pieces of bark it contains will seem spongy to the touch), probably after 2 or 3 years of growth. Another symptom that it may be time to repot is that the aerial roots, at first few in number, start to proliferate. And the fertilizer for the orchid that you add is not longer doing its job.
The best time to do repot an orchid is just before or as the orchid starts a new growth cycle, usually at the end of winter. If, however, your orchid is in bud or bloom at that season, delay potting until it finishes flowering.
The first step in repotting is … to obtain a suitable growing medium. Very few orchids can grow in a standard potting soil: you’ll need a mix designed for orchids, often composed of pieces of bark, coconut fiber, sphagnum moss, perlite, clay pebbles, charcoal, etc. You can find orchid potting mixes in any good garden center, but also at orchid shows and orchid society meetings, not to mention online.
Unlike many plants, you don’t always have to repot an orchid into a larger pot, unless the pot is really full of roots. This is especially true if your plant is a monopodial orchid (single stem orchid), such as the very popular phalaenopsis. Since sympodial orchids (orchids with pseudobulbs or multiple stems) produce offsets at their base over time, a larger pot may be needed in their case … unless you prefer to divide the plant, which is also an option.
There are many kinds of orchid pots. Decorative ceramic ones where once all the rage, but these days, most indoor gardeners use transparent plastic pots (often called inserts). The idea is that, when you water, you’ll better be able to see the state of the rootball with a see-through pot. Typically, these pots are then placed inside a more ornamental cache-pot. You only see the plastic insert when you take the orchid out of its cache-pot to water it (orchids are normally watered by soaking their rootball in tepid water).
Of course, you don’t need to use an orchid pot. There is nothing wrong with repotting orchids into a perfectly ordinary plant pot.
If you use the same pot, do clean it thoroughly before reusing. I just wash mine in the dishwasher, as the hot water sterilizes them perfectly.
Repotting a phalaenopsis
Since potting techniques vary slightly depending on the type of orchid, let’s focus here on phalaenopsis orchids (Phalaenopsis), which after all make up about 95% of all the orchids sold as houseplants. Therefore, your orchid is mostly likely a phalaenopsis.
The day before repotting your orchid, water it. That will make it easier to remove it from its pot. (Dry orchid roots tend to cling to their container.) Also pour a potful of orchid mix into a bowl or pail and soak it overnight so it can absorb some moisture. Simply let it drain before starting.
Remove the orchid from its pot without breaking the roots. To learn how, see How to Remove a Pot With Minimal Damage.
Now, with your fingers or a chopstick, remove as much of the old mix as possible. Don’t hesitate to cut off any dead, rotten or broken roots (they’ll appear brown or soft) with pruning shears, disinfecting them with rubbing alcohol between each cut to avoid spreading disease. Also remove any yellowing leaves or dead flower stalks.
Just before you repot, you can rinse the roots with clean water to remove any dirt.
Add some moist orchid mix to the bottom of the pot (no drainage layer is required). Center the plant in the pot, perhaps somewhat lower than it was in its original pot (in order to cover any bare stem that formed over the last few years), spreading out the roots as evenly as possible. This includes the aerial roots which were probably sprouting outside of the pot and stretching in all directions. You can now direct them into the pot and cover them with mix if you prefer.
Now work orchid mix evenly among the roots, filling the pot nearly to the brim, pushing and pressing down with your fingers or planting tool as you go so that the plant is firmly seated. Finally, spray the growing mix with warm water.
During the first weeks, go easy on the watering. Often a daily spritz of the mix is enough. When you see signs of recovery (usually after 2 or 3 weeks), begin watering as you did before.
You can start to fertilize the freshly repotted orchid in about a month.
And there you go: that wasn’t all that difficult, was it?
Article adapted from one published on February 28, 2015.
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Almost all of my orchids were the common cymbidiums, which grow like weeds. Many were planted in rotten stumps filled with raked up oak leaves. They were useful for accelerating the decay of the stumps. (I probably should have just cut the stumps low and buried them.) As the stumps rotted, I pulled and canned and groomed the orchids. I gave the good ones away when floral buds appeared.