Acclimatizing tissue culture droseras


I just got some tissue cultures of drosera in the mail and planted them out. Given how little information there is on the internet on safely acclimatizing droseras and given how many plants I have killed till I stopped killing them, thought it may help people if I wrote the steps I took. Sadly, being alone at home and not able to find the tripod for my phone, I was not able to video the process or take pictures while I was working.

The plants arrive in plastic vials containing small plants in sterile tissue culture growing on agar based media. The vials are air tight and your race to acclimatize the plants basically starts the minute you crack one open and pathogens can enter the vial and rapidly multiply on the sugars in the growing media. The minute you have done this, the plants can no longer survive in that medium without being at severe risk of fungal infections in particular and must immediately be moved out to growing conditions or new tissue culture.

To transition the plants safely to growing conditions, it is important to ensure that they get intermediate conditions that allow them to adapt in a gradual manner. Here are my tips/learnings from several experiences of acclimatizing tissue culture plants to my conditions.

Growing conditions of plants in tissue culture

  • In tissue culture, the plants have a nutrient dense medium to grow on that allows them all the energy they need to grow rapidly.
  • This nutirent dense medium is indiscriminate – fungus can grow on it with as much joy as a plant (and kill the plant) if you allow it to be contaminated. Therefore, the tissue culture is sterile. The plants have no need to build defenses against normal microbial threats prevalent in the world, because they don’t need to face them while in the tissue culture.
  • The plants are growing in 100% humidity. As a result, the plants don’t need to develop any protection against losing moisture.
  • The plants are usually growing in much less light than normal growing conditions and in any case, they will have arrived after spending several days in complete darkness if they have been shipped to you.
  • The plants often have very few to no roots at all, because the growing media provides nutrition so effectively, the plant has no need to develop a root system while growing in the culture.

Precautions that need to be taken when acclimatizing delicate carnivorous plants from tissue culture

  • Acclimatize plants to increased light
  • Acclimatize plants to lower humidity
  • Acclimatize plants to normal microbial ecosystem in growing area
  • Encourage the plant to develop roots

Steps I take to ensure successful acclimatization of tissue cultured plants to growing medium before deflasking

  • Unless the culture seems to be infected in any way or the plants are in any immediate risk of damage from being left in the tissue culture, I prefer to wait for a week to remove the plants from the sterile flasks. In this week, I leave the plants undisturbed in normal growing area temperature and low light – never direct light – not even bright light. Just giving them a chance to recover from the travel and darkness to some light. I may increase the light they get gradually if opportunity presents, but I don’t stress about it – one week is a relatively short time for any major adaptations. If the plants are doing fine in the flask and growing, I’d probably leave them there for another week or two.
  • Try to deflask at a time when the temperatures are relatively “normal” and you aren’t getting any extreme highs and such (in our area, no question of low temperatures, but I suppose watch out for that too, if your area is prone to cold weather)
  • Mix the growing medium and keep pots ready before deflasking the plants.
  • Maintain a relatively pathogen free growing space. I don’t actually sterilize the growing media before planting the drosera onto it, but I do try to ensure that the growing medium is well rinsed and fresh and the pots are either new, or cleaned thoroughly to prevent fungal or insect infestations from whatever grew in it previously.
  • Keep plenty of distilled or RO water handy for rinsing. You will regret if you run short in the middle of the process. Also keep tools you may beed clean and handy. For me, these would be tweezers and a spoon or two. I also like to have a few clean bowls handy if I want to use them.

My deflasking process for tissue culture droseras

  • As soon as the flask is open, the race against time starts on various fronts. My main objective is to reduce shock (can’t be prevented, altogether, of course), prevent dehydration and prevent contamination.
  • I keep two bowls of water handy. I open the flask and drop the plants into one bowl of water. If the plants are growing well in the medium, this may take slight encouragement to dislodge/scoop them from the agar using the handle of a spoon.
  • Rinse the plants as best as possible without getting brutal about it. The goal is to get any of the agar medium that may be on the plants off. This is one stage I am never really certain of, given that the agar is transparent in water, so it is hard to make out if you have got it all off. Swirling the plants in the water a bit helps.
  • I pick individual plants and check them for remaining agar medium as best as I can before putting them in the second bowl of clean water. I have found that adding a touch of fungicide to this water gives me better results, but I have had plants grow successfully without the fungicide too. Trichoderma viride works too, though I have heard that some droseras don’t like it. I haven’t had problems so far. I suppose you could play safe and use sulphur or Mancozeb or something.
  • This is also the time I separate plants that may have got tangled with each other. I do as little of this as possible, and only for plants that are tangled with roots facing in the opposite directions, so that if I planted them as they were, one root would be in the media and the other in the air – those must be gently pulled apart. For plants tangled with roots facing in the same direction, I don’t bother to separate them, unless they fall apart on their own while swirling in the water or handling. This is because i want to keep the mechanical damage to the plants to a minimum – the goal at this stage is not to have as many individual plants as possible, but to get as much of the living plant matter to survive the transition. I can always separate those that survive later if need be when they are well acclimatized and growing robustly.
  • I never ever break apart plants growing as a clump. This happens quite often with tissue culture plants, where several plants grow out of a “blob” of plant matter base (callus, it is called properly, I think), often with few or no roots between the whole blob. If the plants are connected at the base, I don’t break them apart, I treat them all as one plant.
  • This whole thing takes longer to type than do. Put them in the water, swish them around, separate what separates readily, move to clean water.
  • The plants can rest here for a bit in the water, if there is anything you need to prepare for the next steps. The water will prevent them dehydrating.

Planting newly deflasked tissue culture droseras

  • Growing medium for the unflasked tissue culture droseras should be whatever you use for normally growing your droseras.
  • Before you touch the plants floating in the water, make sure you have something to cover the pots with as soon as the plants are planted. Putting them into a plastic bag, as I have done works. Putting a transparent cup on top of the pot works too. Whatever you choose to give the plants 100% humidity after planting should be ready to deploy as soon as the plants are planted into the medium – I can’t stress this enough.
  • This is not the time to toughen them up. They are used to 100% humidity. Give them 100% humidity – I have found this to have direct impact on survival rates – though strangely I haven’t read too much stress on this on the internet. Probably because a lot of the instructions are for tougher plants – orchids, bananas and so on. Drosera are way more fragile, I think. Minimizing potential for dehydration in the deflasking and planting process is important.
  • Keep them in water till the point of being planted. Cover them immediately after planting. Yes, this means covering each pot up as it is ready instead of waiting to cover all after all the planting is done. At least I have done it like this on the times I have had better success.
  • Sometimes, when planting the blobs, it is hard to make out what to plant and what to keep out, because the plants may not be formed well enough to make sense of as “this is root, plant this in media”. For plants like this, I make a shallow depression and put the whole base into it and sort of nestle the growing media some way up around the plant. So it gives the base media to root into, and also sort of cups the plant lovingly in case it wants to root from other places.
  • When done, put the plants in a place where they get moderate light – not too bright and definitely not direct. Make sure they have water – whether in the plastic bag you put pots into – as I have done in this case below – or whether standing in trays. This can’t be stressed enough. If the pots dry out, your plants are history.
  • Click a photo of how your plants look at this stage. You will see why later.
  • Now for the acclimatization.

Acclimatization of tissue culture plants in growing media

If you did everything right, at this point, you will have plants planted into moist growing media, full humidity and low to moderate light. If you look back to the week of letting them sit and recover from travel, you will notice that their conditions now have changed growing medium and a lack of sterile conditions, but other conditions remain what they are used to – low light and 100% humidity. So in essence, we are breaking down all the things they will have to adapt into small, doable chunks.

Keep them like this. They should be able to grow like this indefinitely if need be. There is no hurry. Hurry before the plants are ready will kill them. This is a good time to remember that the most destructive pest in a garden can be an eager novice gardener. Leave them alone to do their thing. Don’t even look at them if it will tempt you to touch. For a week at least, no matter what the plants do, short of getting an infection and dying, ignore it. Some may wilt. Leaves may die on occasion. Resist the temptation to interfere and do something to save – it will only add to the shock. There isn’t much you can do at this point apart from ensuring they have humidity and some light but not overwhelming. Remove any plants that die, of course. But if you did things right so far, and began with a healthy culture and removed most of the agar, there shouldn’t be any dead.

After two weeks, you can begin thinking about acclimatizing them to the other things they need to adapt to. This is the riskiest part of the process.

  • I like to follow an individualized process instead of putting all the plants through the same acclimatization regardless of their condition.
  • I examine all the pots and compare with the photo I took when I planted them out. What I am looking for is signs that the plant is well adapted so far, before adding to their stress.
  • Signs I look out for include new growth and dew formation on leaves. The new growth is self explanatory. It means the plant is adapted from the stress and back to its main business of growing. In well adapted plants, this growth can seem dramatic. From the ragged clumps of green that get planted, you have miniature plants glistening with dew. This also usually indicates root development. These guys are ready. The rest get more time to wait and get there.
  • There is no hurry. If some plants in a pot seem to have adapted, while the others are still struggling, it is a good idea to wait till they are all doing better, because of course what steps you take will happen with all the plants in one pot, unless you potted each plant up separately – which I rarely do for lack of space.
  • With plants that are well acclimatized, this is a good time to take off or open whatever you have been doing for humidity and take a moment to admire your plants. Maybe a few photos. Then close it back up and let it be. Do this a couple of times over the next few days. What you are doing is letting the humidity drop for a bit before returning it to 100%
  • You can do the same with light. Move them to brighter light – particularly when they are open – bright light encourages dew formation, and helps the plant not lose dew outside the humidity cover. Avoid direct sunlight too soon, but once the plants are open several times a day without suffering, it should be fine to expose them to early morning or late evening direct light.
  • After a few days of opening them briefly, you can open them up for a while carefully and away from direct drying breezes like a fan. You can leave them open for say half an hour or so before returning the humidity. You can mist them a bit on occasion if needed to delay covering them up. Don’t overdo it. Misting is not watering.
  • Once you have your plants in the open for over half an hour several times a day, you can try feeding them with very small insects to boost speed of growth. Be very careful while doing this. High humidity encourages mold
  • Then I change tactics and leave a small opening in the bag or if using a glass/dome, I lift it up a bit from one side. And leave it like that after leaving the plant open for a while. The humidity will be high, but not 100% – there will be some ventilation. Other ways to reduce humidity can be poking holes in the cover or leaving the cover open from the top while still protecting from breezes from the sides.
  • If at any point the plants look like they are wilting or they lose their dew, increase humidity a bit.
  • Basically, you then increase this exposure to low humidity slowly till they are finally in open pots and growing normally.

This is a time consuming phase. I have done it over a month and still lost plants to shock. This time I’m planning to take two months.

I have found that I start feeling ambitious as the plants do better and tend to skip precautions and make drastic changes thinking the plants can take the shock. Invariably I am wrong and end up losing plants. A plant doing better means they are adapting well to the conditions I have already given them – not the conditions I will be giving them. This means that small steps are working. Not that large steps will work. This is important to remember, because if you are like me, you want the plants to be growing normally already and want to interpret all observations to mean that they can handle more and more. I cannot overstate the importance of understanding that this is a stressful adaptation for a plant and a plant doing well is definitely a call for celebration, but not a call for increasing stress on it.

Just like a school child scoring well in exams doesn’t mean they should be made to study 24/7.

This time, I am hoping to not lose any plants at all. I am planning to give the plants an extra few days when I see them thriving before adding a new stress.

 

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