Transplant shock, what it is and how can you minimize it

Transplant shock is actually a combination of three factors. The plant undergoes a certain form of physical abuse, is reduced in size, and ends up in a new environment.

It’s important to know that each of these factors contribute to transplant shock. Let’s take a look at how to lessen the negative impact of this and protect plants from transplant shock.

Symptoms of transplant shock

A plant that was newly dug up and moved from one place to the another may show signs of wilting or falling leaves, dying branches, abrupt fall of flowers or it might die altogether. This is called transplant shock.

A new growing environment

First of all, the most important factor is the change in growing environment. When a plant is displaced, the following usually change radically:

  • soil type – even in the same garden, soil may be clay on one side and humus-rich on the other, with “spots” of different soil types embedded.
  • drainage – drainage and availability of water differs both because of different soil types and different rainfall patterns (overshadowing trees, differences in gusts of wind, etc…)
  • exposure – unless you’re moving from one corner of an open field to another, there will always be a different pattern of exposure to the sun and shade.
  • companion plants – to a lesser degree, the neighboring plants will also influence the newcomer. A relationship is always established between a plant and its neighbors, so having new neighbors influences this, too.

A plant, as it grows, responds intimately to its environment, to “bloom where it is planted“. The shock of change can be overcome, but in some cases proves to much to cope with, and the plant dies.

Physical abuse

Transplanting cannot be performed without some degree of damage to the plant. This is typically caused by the cutting with the spade, the pruning, parts of the plant dying off due to mishandling, transportation and such.

Part of it is directly related to how hastily work is done. Being goal-oriented is good, but being careful is good, too!

Downsizing

Parsley seedlings show the spread of roots to leaves to demonstrate how losing roots induces transplant shock.A plant that has been transplanted from the where it used to grow in the ground typically loses half or more of its root system and production system: leaves, branches, etc.

Since it had evolved to meet the needs of an increased circulation of sap, water, nutrients, etc, the vessels that channel all these aren’t adapted anymore. Their size isn’t optimized as it used to be. It costs the plant more to shift nutrients around than it used to.

This is the main logic behind the practice of evening out what is removed: if half the root system is lost in the transplant, then it’s important to reduce leafage by half as well. It’s important to ensure that the proportion of roots stays relatively the same to that of live branches and leaves.

Also, remember that the bulk of the “active” roots are around the circumference. Roots around the trunk are still good, but usually they’ve already depleted the soil around them and aren’t as important. When transplanting, they’ll have to start getting to work again, which takes a while!

How to minimize transplant shock

For each of the three factors listed above, an appropriate response can minimize the transplant shock.

Countering the downsizing

For an unpruned plant, the roots usually extend to the same extent as the branches do. This is called the drip line. Since encasing the entire root system is often impossible for shrubs larger than two or three feet (½ to 1 meter) tall, a rough rule of thumb can serve as a guide:

  • prune back the branches in proportion to the root clump.

For example, if the shrub was three feet across and the root clump that is left is only one foot across, cut the branches back by two-thirds.

  • It’s safer to cut too much away from the branches than to not cut back enough.

In other words, better to prune more than not enough.

In some cases, it’s even recommended to cut individual leaves in half, too. A small stub remaining attached to the stem keeps the branch alive while not demanding too much from the smaller root clump. This is especially done to protect species that don’t react well to pruning like Prunus species (cherry tree, plum tree, ornamental plum trees, etc).

  • Lastly, remember to water often for the entire next season.

Countering the physical abuse

First of all, it helps to handle the roots and plant delicately.

  • Avoid tugging in a jerky fashion.
  • When you uncover a root, cut it cleanly with sharp, sterilized pruners or loppers.
  • Don’t twist the plant around.
  • Better spend time digging around to form a complete circle rather than only cutting half-way through.
  • Use a sharp spade to mark the circumference, and follow-up with pruners to make nice clean cuts out of torn roots.

Integrating the new environment

Let it sit for a while – When transferring a plant to a pot, it’s good practice to sit the pot where the original plant stood for a few days, ideally for a week or so.

This ensures that many environmental factors remain the same (exposure, wind, moisture). Complement with water regularly during this period.

Don’t do this if you plan to transfer the plant to the ground in another place, because then you’re simply losing time that the plant can use to adjust to its new growing environment.

Bring friends along – When uprooting the plant, if there are any appealing or useful neighbors in the area, you can also add those to the transplant program so that whatever symbiosis they’ve reached can be maintained. If nice bulb flowers grow at the foot of your shrub, bring a few along, too. Spices interact a lot with their environment, too.

Mix in old soil – Use up to 50% of the old soil together with soil mix for backfilling or planting to a pot. You’ll be bringing beneficial fungus and microorganisms along for the transplanted plant.

Protect from too much light – If you’ve got a shading net that cuts off some of the light, use it for the first season to protect the transplant, especially in summer.

Performing these steps will ensure you minimize mortality and give every shrub the best shot possible. Even a fickle, delicate plant like Stephanotis can survive with such delicate attention!

Smart tip about reducing transplant shock

A study was conducted on young birch saplings that were transplanted: dousing the soil and watering them with sweetened water significantly reduced mortality and transplant shock. Why not try it out for your own shrub transplants? Add a cup and a fourth of sugar to one gallon of water (10 oz per gallon or 70g per liter) and use that for watering for the first season.


Credits for images shared to Nature & Garden under © CC0 1.0, all edits by Gaspard Lorthiois:
Spades and shrub shared by menita
Parsley root-to-leaf ratio shared by Hans

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