So, you finally got your first tissue culture plant and now you're staring at a tiny plant growing in a bag filled with gel wondering what to do next. The process itself is fairly simple, especially if you have ever propagated a plant, or grown a plant from a corm or a seed. But there is a process, and skipping it is how you end up with a pile of mush instead of the plant you've been dreaming of.
What You'll Need
- Clear Humidity Dome, Cloche, or Cabinet
- Small Nursery Pot or Corm Cup (If your Humidity Dome Doesn't include one)
- A high humidity potting mix (Fluval Stratum and Perlite, Tree Fern Fiber etc)
- Distilled Water
- Physan 20 (optional)
Before You Start
First, let's clear up a common misconception. Your plant is not currently in a sterile environment. These plants were already exposed to the outside air when they were removed from their flasks and individually packaged. We aren't worried about contamination. Acclimating tissue cultures is simply taking a plant that was used to 100 percent humidity and slowly acclimating it to your home's ambient humidity. That's it!
Second, not every tissue culture survives. Some species and cultivars are easier than others. You're going to send some plants to the great compost pile in the sky while you learn how to do this (I did too). Over time you will learn what methods, substrates and processes work best for you and before long you'll be a master at this.
Note: There's no need to deflask your plant the moment it arrives. As long as it looks healthy, it can stay in its bag in a cool spot with low light for days or even weeks. Wait until you have everything you need and a chunk of time to do it right.
Step 1: Get it Out of the Bag
This is it! Time to get your plant out of the bag. Grab a pair of scissors or a knife and carefully remove your plant from its bag/vial. Your plant is likely a little bit more... slimy than you were expecting. We will deal with that next.
Step 2: Clean off the Agar
That slimy gel is called agar. It's been feeding your plant during its journey to you and is packed full of nutrients. Unfortunately, it's also really great at feeding and growing mold so it's got to go. Fill a small bowl with distilled water and remove all of the slimy agar from the roots, stem and leaves of the plant. Be thorough but be gentle. Losing a few or even all of the roots is fine here. You just don't want to snap the stem of your little plant. You will know you are finished when there is no agar remaining and the plant no longer feels slimy. This is also the time to remove any yellowing leaves or dead plant matter.
Step 3: Disinfect (optional)
Disinfecting your tissue culture plants after cleaning off the agar is optional, but I find that taking the time to do it has improved my success rate greatly. In a bowl, add 3 cups of distilled water and then stir in 0.1m to 0.2ml (roughly 4-8 drops) of Physan 20. Place your plant into the bowl, fully submerging it to start (it's fine if it floats up after that) and soak for 2-5 minutes.
After soaking, rinse the plant off with fresh distilled water.
Step 4: Pot it Up!
For most plants, a mix of 40% Fluval Stratum and 60% Perlite is the way to go. It's got nutrients in it and is designed for aquarium use, so high humidity isn't a problem. For plants that prefer to stay a little drier during acclimation (Anthurium, Begonia, finicky Alocasia such as Nobilis) we use Tree Fern Fiber mixed with a little perlite. When in doubt, start with the Fluval mix and if a plant melts, try Tree Fern next time for that plant.
Fill your pot 1/3 of the way up with your substrate of choice, place your plant in the pot and add more substrate until it almost touches where the lowest leaf connects to your plant. Be sure not to bury any leaves or petioles as these can rot, which will end your plant's journey before it even begins.
Step 5: Watering
It's time to water your plant for the first time. Your goal here is to water enough so that the substrate is lightly moist but not sopping wet. Remember, this plant is going to spend the next few weeks in upwards of 100% humidity. It is likely you won't need to water this plant for 2-3 weeks. I tend to use a squeeze bottle when I water tissue cultures as it slows me down enough so that I don't over saturate them.
As far as when to water next, wait until your substrate is mostly, but not completely dry. One of the reasons I love teaching and using fluval stratum is that it turns chalky and dusty when it starts to dry out. If you see that, it is definitely time to water again. But remember, we aren't rushing to water again. If you still see droplets on the lid of your humidity dome it's unlikely that your substrate is dry.
Note: I often use our corm cups when acclimating tissue cultures. However, I don't fill the self-watering reservoirs until the plant is acclimated. When in 100 percent humidity a reservoir isn't needed and will keep your substrate too wet for some plants.
Step 6: Acclimation
This is the step you can't rush or skip. Your plant has been in 100 percent humidity for its entire life. If you try to put your plant directly on the shelf it is unlikely to last more than a few hours.
Once you have a spot picked out, place your plant in a humidity dome, acclimation box, or cabinet that can maintain between 85-100% humidity. In a pinch, a clear Starbucks cup works when placed upside down over your plant.
During this process your plant needs light to grow. Place your plant somewhere with moderate indirect light. I place mine on shelves under Barrina T8 lights that are on for 14 hours per day. You can also use natural light by putting the plant a foot or so away from the glass.
This is the general timeline for acclimation but don't take the "weeks" as literal weeks. These are more like checkpoints. If your plant shows signs of stress after advancing to the next checkpoint, you need to stop, potentially go back a "week," and slow down.
- Week 1: Dome fully closed. Open briefly every few days to check moisture.
- Week 2: Prop the dome slightly open or poke a few small holes in the bag.
- Week 3: Leave the dome cracked or remove it for a couple hours each day.
- Week 4: Remove the dome entirely and continue monitoring for stress.
The key word is gradual. Pulling the dome off too soon is the most common reason TC acclimation fails. I often will not advance beyond "week 1" until I see new roots and my first new leaf hardens off.
Troubleshooting
- Leaves going translucent or glassy: Substrate may be too moist. Reduce humidity slightly and increase airflow to dry out the substrate a little.
- Leaves turning crispy: Humidity dropped too fast. Reseal the dome and slow down.
- Black or mushy stem at the base: Too much moisture in the mix with not enough airflow. Check that your medium isn't waterlogged. This is often not saveable.
- White fuzz on the roots or soil: This is likely mold. Increasing airflow will typically resolve it quickly.
- No new leaf growth after 4+ weeks: Not necessarily a problem, but can be an indicator that your plant isn't receiving enough light. As long as roots are white and firm and there's no rot, be patient and give your plant time to feel comfortable pushing growth.
Step 7: Freedom!
Once your plant is acclimated to your ambient conditions you can now start using self-watering reservoirs if desired. Don't rush your first repot. Wait until the plant is fully rootbound.