Bare-Rooting & Repotting Orchids
While orchids do not need to be repotted as often as regular houseplants, they do need attention every once in a while. For most orchids like Phalaenopsis, Cattleyas, Oncidium alliance and Dendrobiums you may only need to repot every 2-3 years, as the potting medium breaks down and the plant out grows its current container. For more moisture loving orchids such as Paphiopedilums, Phragmipediums and Miltoniopsis (Pansy faced type) repotting may be needed as often as every 12 months since more frequent watering may lead to a faster breakdown of the growing medium. One important factor is you should never repot an orchid that is currently blooming or getting ready to bloom. If you must repot an orchid with a flower it is recommended to cut the flowers off.
Selecting Appropriate Potting Medium and Growing Container
First, your new container should only be large enough for 2 years new growth and no larger. Using a container overly large will end up retaining too much water and you might end up with rotten roots before too long. Keep in mind the size of your most recent new leaf or lead. As your plant grows, each year’s growth will be as large as or only slightly larger than the previous year’s until mature size is reached. Most orchids only make one new growth per year so picking the right pot size is very important. We recommend plastic pots for most orchids since they are less expensive to use and also maintain water in the pot evenly. However, for most people clay pots vs. plastic pots is a matter of preference. Clay does dry out faster, so if choosing this be prepared to water 2-3 times as often as plastic. For most orchids in smaller pots, up to 3 ½” in diameter a fine grade fir bark or cypress media is best. We use our large grade Orchid Mix for most of the orchids that we transplant into 4” and larger pots. Always use pre-moistened medium when repotting or transplanting orchids, since dry medium can dehydrate tender root tips.
Trimming Roots and Removing Excess Debris
Repotting is an excellent time to not only remove any dead or unhealthy looking roots but also to remove excess debris such as old bloom stems and the dry sheath around mature pseudobulbs. (This dry sheath provides a wonderful home for harmful insects so we recommend removing this as a precaution.) The next step would be to trim your existing roots to encourage new root growth. (Do not cut roots on Cymbidiums, Ladyslippers or other terrestrial orchids). With most orchids, after roots have been disturbed they will not continue to grow and will in fact slowly die off as new roots grow and fill out your container. We trim the roots (this applies to most Cattleya, Oncidiums and other epiphytic sympodial growers) to reach a depth of about one-half or two-thirds of the new container selected. This is enough to steady the plant in its new home until new roots form. Cutting any plant tissue should always be done with clean, sterile scissors or shears. Cutting tools can be sterilized by exposing all cutting surfaces to the hottest part of a flame for 10-15 seconds or by soaking them in a 10% Clorox solution (3-5 minutes). Using clean cutting tools will reduce or prevent the spread of plant born disease such as orchid virus or fungal and bacterial problems.
When the plant is cleaned and ready to be planted, hold the plant upright in the empty pot with the roots spread out and fill between them with potting medium, shaking slightly to settle mix until roots are covered. Ladyslippers and Phalaenopsis should be held in the center of the pot while Cattleyas, Oncidiums and Dendrobiums should be placed close to edge with the new growth facing ready to grow across the widest portion of the pot. Slightly firm the mix around the roots using your fingers without packing it too tight. There should air pockets to allow for drainage, but the plant should be steady enough to hold itself upright
Watering and Fertilizing after Repotting
We often water freshly potted plants once with a solution of a root growth stimulant (either Superthrive or Dyna-Grow KLN). Thereafter, water should be held off for some time to encourage new roots. The following methods are recommended based on our current potting mixes.
For orchids grown in cypress based media or douglas fir bark (Roots trimmed)
Misting on bright, clear mornings should be more than enough until new roots appear. Simply use a spray bottle with fresh water and mist the foliage and the top of the new medium. This “shock time” as we call it, helps maintain some humidity in the pot but allows for new roots to start at the base of the plant. This may take anytime between 2-5 weeks depending on your conditions and the time of year. Increased watering should begin when new active roots appear in and around the pots. The roots will follow the water into the pots over time, so gradual increased watering is recommended. After new roots appear, young plants in small pots may dry more quickly and may therefore benefit from more frequent watering. After roots have reached the edge of the pot and gone down into the new medium you can continue your regular fertilizing schedule.
(For suggested watering of specific plants see our other culture sheets but remember everyone’s conditions are different and these are suggestions only.)
Orchids grown in Peat based media (Phalaenopsis, Jewel Orchids and Cymbidiums)
We do not suggest misting orchids grown in peat based media as this can promote fungal and bacterial problems. Instead, after using a rooting stimulant, allow the mix to dry out throughout the pot (This can take as long as 7-10 days for larger pots.) Water just enough to dampen the potting media and to start running through the drain holes. Continue this abbreviated wet-dry cycle as the roots follow the water into the pots. A gradual increase in watering is recommended. After roots have gone down into the new medium you can continue your regular fertilizing schedule.
Orchids grown in Sphagnum Moss based medias.
Orchids like Oncidiums, Phragmipediums, select Phalaenopsis and other moisture loving genus might do best in a media that uses sphagnum moss. The trick with this moss is to not over-pack and to replace every 18 months or so, as soon as it sours. You will not need to mist or withhold water when repotting into sphagnum moss. Instead, we wait until the mix has almost dried out and water again lightly. You can add amendments like spongerock, expanded shale, lava rock, or loose tree fern to the moss to help keep it 'open' and well draining.
Exceptions to the reduced watering are most orchids where the roots are not cut, such as Ladyslippers, some Phalaenopsis, Cymbidiums, Stanhopeas and material grown in baskets or on mounts. These can be usually watered and fed as prior.
Light, Humidity and Air Movement
Light and air movement are valuable components when it comes to starting and growing young plants. Bright, indirect light exposure is what should be provided for good, rapid growth habit. If you have adult plants in the same growing space, remember, that newly potted plants can be stressed under adult conditions. Even mature plants need more moderate temperature and light when being re-established to avoid extreme shock. (Remember, you are withholding water to help those roots grow so excess temperatures and light may be harmful.) Try to maintain a higher humidity (about 70% to 80%) and moderate conditions around the new plants. (68o-74o) If you are growing under artificial lights, maintain 16 to 18 hour days. Gentle moving air can help in the growing environment. This will help prevent bacterial or fungal problems from the extra misting you are supplying.
**Since root-trimming is a matter of preference to some growers, we do not remove any live roots before shipping orchids to customer’s bare root**