Being sympodial type of orchids, Cattleyas produce several new pseudobulbs that rise vertically from a horizontally extending rhizome. Within a year or two, they begin growing out of the pots, which is why most hobbyists resort to dividing their cattleya into back bulbs and newer growths. Both divisions can be repotted in newer and larger pots.
As a rule, I do not encourage dividing your orchid, unless warranted. A conservative attitude serves best in growing them into large specimen sized plants. So repotting into a larger sized pot would be the obvious choice.
But when you have space constraints and do not want to have an overgrown, unruly plant, then it is best to take a more practical approach and consider dividing your plant into two divisions. The reason being that leaving the plant to put out further new shoots will only put the plant at risk, as all the new growths will grow outside the pot. Not only does this jeopardise the plant by way of getting bruised or tender new growths snapping off, but an unruly lopsided growth also looks aesthetically unappealing.
Recently, I was faced with this situation, wherein my Caulocattleya Chantilly Lace had some old pseudobulbs taking prime space in the pot, while the newer growths were extending awkwardly out of the pot. Going in for a bigger pot was out of question as my balcony grow space does not cater for larger pots.
Secondly, given that most of the pseudobulbs were done blooming, and that the plant is a vigorous grower, putting out four-five new pseudobulbs in a year, I took the call on dividing the cattleya, and repotting it, so that it grows well, and is safe from the risk of getting bruised or broken. The section with the older pseudobulbs that were potted separately, would also subsequently develop new pseudobulbs.
With this in mind, I set about dividing the plant and repotting the divisions as follows:
- Preparing the plant for dividing and repotting
At the outset, I prepared the plant for dividing and repotting it, by fertilizing it two days prior to the project. Doing this ensured that my orchid absorbed nutrients and would be able to better withstand the shock of dividing it and repotting it.
Secondly, once I repot the orchid, I usually fertilize it only after two-three weeks. Doing this slows down the metabolism of orchids and leads it to a temporary state of dormancy. This slowdown in activity will allow the orchid to redirect its energy into recovering from the shock and subsequently put out new roots and shoots once fertilization is resumed.
- Sterilizing the work surface and equipment
I began the project by sterilizing the work surface by swabbing it with 10% bleach. I sterilized the equipment such as cutters and tweezers by rubbing them with surgical spirit.
The steel tweezers and cutters can be flamed for extra effectiveness, as this eliminates any microbes that may survive. Always ensure extreme caution while doing this. Also, keep the surgical spirit away from the flame as it is inflammable and could lead to accidents.
I then lay down all the sterilized equipment, as well as the stakes and string/wire-ties neatly, so that it becomes convenient to pick and use the right tools for the process.
The tweezers are especially useful to reach into nooks and crevices and remove dried sheaths, tease out roots and separate them from the plant before eliminating the dead roots. This easy accessibility also prevents us from accidentally cutting off good roots or sheaths.
With its great value-for-money offer, I bought this set of four tweezers from Amazon and highly recommend the same for your orchid maintenance kit. You can check out the same here.
- Unpotting the orchid and inspecting it
In order to understand where to divide the orchid, you can make a rough assessment by checking out the plant.
However, do not rely on this method alone, as it could be misleading. A better way would be to unpot your orchid, remove all the old media and check out the rhizome of the plant. For all you know, the rhizome will give you a completely different perspective on the growth direction of the orchid.
On inspecting my orchid, I decided on dividing the plant into two sections, one with old canes and the other with the newer growths. However, this was not to be.
- Assessing the plant and dividing it
Upon unpotting the orchid, I found that the rhizome was dark and moldy in two places. Apparently, it was suffering from rot issues due to the continued exposure to dampness and inadequate air drafts. This happened because the older pseudobulbs were at a lower level than the newer growths that were successively placed higher than the older pseudobulbs.
To know more about rot issues in orchids and their treatment, read my post, How to save your orchids from pests and diseases.
I quickly removed all the LECA (Light-weight Expanded Clay Aggregate) pellets, except for the ones stuck to the roots. I rinsed the rhizome and roots with mild liquid hand wash soap.
Doing this superficially removes dirt and also removes mold and other microbes/pests. It also helps in better assessment of the orchid’s condition and planing the best course of action.
When faced with a similar situation, if your grow space allows it, you could pot two of the best divisions together to get a specimen sized plant with multi-directional growth or you could exchange it for another plant or; even better, you could either sell it or gift it to a friend.
In order to treat the same, I improvised my plan and ended up cutting the rhizome in three places and eliminating one old decaying pseudobulb. This gave me four divisions instead of two, each having two to four pseudobulbs. I wasn’t pleased about this development, but nonetheless, decided to repot all four of them separately and give them a chance to grow into four different plants.
- Prophylactic treatment of the divisions
First things first, I needed to treat the diseased parts. Since the rot was superficial, I congratulated myself on discovering it in the nick of time, before the rot spread to the other sections of the rhizome. I scraped off the blackened rotting tissue from the rhizome until healthy tissue began to show. I again rinsed the sections and placed them in a shallow dish.
I then poured 3% hydrogen peroxide on the rhizome and roots of all four sections and allowed them to fizz for a good ten minutes. Doing this effectively kills the bacteria and fungi that were causing the rot. Spot application of powdered cinnamon at the cuts would further ensure the wounds dry up fast and reduce chances of reinfection.
- Repotting the divisions in suitable media
I chose four medium-sized pots for planting the divisions. Since, the orchid was already growing in semi-hydroponic medium, I used pre-sterilized LECA pellets to repot three of the divisions.
Using semi-hydroponics pots with a reservoir to hold water and nutrients, I positioned the plant appropriately, so that the new divisions that would arise, would have plenty of space to grow. I filled the pot with LECA pellets, all the while patting it to pack the medium in as compact a way as possible.
I decided to experiment with organic medium and so repotted the division with the oldest pseudobulbs in organic bark mix, along with strips of synthic, which is a moisture-retentive medium used in place of sphagnum moss.
I positioned the oldest cattleya division in the centre as I have no idea, where the new growth will emerge. I layered the pot with synthic strands at the bottom and topped it with a layer of bark chips. I repeated this layering till the top and finished off with a layer of bark chips. This will ensure there is a good balance of air and moisture in the medium, which will encourage healthy root growth. I placed a stake to support the division, and ensured it is held in the desired position by tying it up with a string.
For more details on choosing pot size and the right organic potting media, read my post, Everything you wanted to know about organic media for growing your orchids, which discusses the topic at length.
- Post repotting care of the divisions
I placed the newly potted division in my grow space and have been checking on them to ensure they don’t dry up. I will begin fertilizing them after two-three weeks, since this quiet period of inactivity will help them recover and establish themselves better.
To begin with, I will begin fertilizing with half the recommended strength of NPK 20:20:20 (100 TDS), calcium nitrate and magnesium sulphate. I will also add seaweed kelp once a month to the fertilizer.
Watch out this space for updates on how each of these sections develop.
Until my next, happy growing!