Repotting a Phalaenopsis Orchid
By Hedy Koski
Orchids belong to a group of plants called epiphytes (air plants that don’t grow in soil). Repotting your phalaenopsis orchid (also known as a moth orchid) in a new orchid mix is required every couple of years, as the old orchid mix will start to decay and could make it too acidic for the plant to thrive in. Let’s cover some repotting basics. An ideal time to repot is when your phalaenopsis has finished blooming. Water your orchid well, as this will make it easier to remove all the old mix from the roots. Gently remove the plant from the pot. Get rid of all the old orchid mix, and rinse off the roots. Now it’s time to inspect. Good roots are firm and plump—they can be silvery-white, yellow, or green. Silvery-white roots are typically ones that grow out of the mix, yellow means they haven’t seen sunlight, and green contains chlorophyll because they have received sunlight. If roots are mushy or shrivelled they need to be cut off, with sterile clippers, just up to the healthy part (not in the healthy part). The healthy plump part of the root is called the velamen— it is the sponge for the fine root in the centre. If the velamen has completely rotted away from the root, you’ll see strings (the actual root). You can cut those stringy roots off if there are lots of other healthy plump roots, but if very few roots are left you can leave the stringy roots to help stabilize the plant in the orchid mix. If the roots can still fit in the same pot, there is no need to “pot up” (planting into a larger pot). But if your roots have outgrown the old pot it’s time for a new one, just slightly larger. Aerial roots (typically those silvery-white ones) don’t grow down in the pot, but sideways and out. Do not bury or cut off these roots. Bottom drainage in your pot is important—the addition of holes or slits in the side of the pot helps with airflow so the roots don’t stay wet for long periods. Add a layer of new, moist orchid mix to the bottom of the pot, place the roots in the pot, and fill with the mix. Tapping the side of the pot helps the orchid mix settle between the roots, eliminating any gaps. Wipe the leaves clean and you’re done! Wait a month before you fertilize after repotting. Watch for signs of transplant shock, such as yellowing or soft leaves. It is a possibility, especially if many roots have to be trimmed. Another reason for transplant shock can be changing the type of orchid mix—switching from straight sphagnum to a bark mix, for example, as sphagnum moss stays wet longer than bark mixes. To help eliminate shock when switching, it is advisable to water a little more frequently for a few weeks than you did with sphagnum moss, then ease into your normal routine. Phalaenopsis orchids are resilient and will adapt to their new routine quickly. Enjoy your phalaenopsis orchid. They are beautiful plants to have.