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Transplant “Adaptation”

This article is in response to the often-asked question “How long will it take for my plant to get reestablished after repotting?” – especially when a plant is first moved into semi-hydroponics.  In fact, the phrase “transplant adaptation” is something of a misnomer.

Orchid roots grow tailored to the environment they are in, and once grown, cannot change. Because of that, whenever you are changing the local root zone conditions – whether that is by changing the medium (any, not just S/H-related), or drastically changing the overall conditions, as when a plant formerly grown in a Hawaii greenhouse gets to your windowsill – you have to be aware that the plant will need to grow new roots that are “right” for the new conditions.

If the old and new environments are similar, or the new one is an improvement (soppy sphagnum to moist LECA in semi-hydroponics, for example), there is no real adjustment necessary, and the plant continues growing as if nothing has happened, or in the case of the improved airflow of my sphagnum-to-S/H example, will take off and grow better.

If, on the other hand, the change in root zone environment is vastly different – coming out of dry bark and into moist sphagnum or semi-hydroponics, for example – the old root system may be virtually useless and an entirely new set of roots will need to grow before the plant has fully “adapted”.

Keeping those two extremes in mind, you can see:

  1. That the time period for a plant to become well-established in S/H is quite variable and dependent upon the particular situation,
  2. It is important to time the conversion to coincide with the formation of new roots, so that they can grow to function the most efficiently in the new environment, and
  3. One should go to the final state immediately, not try to do a “transitional” set of conditions in between the old- and new ones, as that sets the plant up to do a second round of adaptation.

I have found that the ideal set of conditions for a successful transition include all of these:

  1. The plant, and especially it’s roots are healthy and strong to begin with.
  2. The plant is actively growing brand new roots.
  3. The roots have been cleaned of all old organic matter.
  4. Mineral-free water is used to soak the medium and water the plant.
  5. The plant is kept very warm – in fact, I use bottom heat for all new plants these days.
  6. The plant is kept shady.
  7. The plant is kept in very humid conditions.

Those first five factors favor the stress-free growth of a well-adapted root system, while the last two minimize the stress on the plant while it does so.

So what about the situation in which new roots aren’t emerging, but the current potting situation is “guaranteed death” under your conditions, or – let’s be practical here – we have “jumped the gun” and made the move at the wrong time? In that case, we are dealing with a compromised root system that will be less able to take up water, while the plant continues to process its stored water and carry on its normal respiratory processes, so may be losing water faster than it can be replenished. My approach is this:

  1. Pot the plant up and water it in. Adding a growth stimulant like KelpMax to the water will help greatly.
  2. Invert a clear plastic bag over the plant and pot, but do not seal it. The idea is to maximize the humidity around the plant, slowing water loss, without setting it up more mold issues.
  3. Move the plant to a warm, shady location. The warmth will accelerate growth – place the pot on a seedling heat mat if your conditions are colder than the plant prefers – and the shade slows down photosynthesis which consumes a lot of water.
  4. Be sure to keep the medium constantly moist, as that’s what you want the new roots to be “tuned” to, and the moisture helps keep the humidity up.

In a few weeks, new roots will have emerged and begun to penetrate the medium, so you can remove the bag and transition the plant back into its preferred growing environment.