Transplant shock is a natural occurrence whenever a plant is uprooted from its former home and moved to a foreign environment.
Moving a plant from one place to another is not as simple as digging it up, plopping it in the ground and hoping it will be fine. Plants that undergo too much transplant shock can be open to diseases, pests, and can weaken them to the point where they never fully recover. If they are food plants, you may notice a smaller harvest, or no harvest at all.
While plants that have already established a good size root system have a better chance of recovering from the transplant process than young plants or home-grown seedlings, there are certain steps you can take to ensure success.
Although you can transplant plants any time of the year that the soil is workable, the best time to do this is generally the beginning of Spring and the Fall.
It's possible to transplant in the summer, but more watering and care will be needed as the plant will respond much more slowly as it battles both the transplant and the heat.
As a general rule, perennials that bloom in the spring are best moved in late summer or fall. These include plants like Bleeding Hearts, Astilbe and Peonies.
Fall bloomers, like sedum, asters and coneflowers, are best transplanted in early spring.
Since it takes six weeks for perennials to become established in their new home, if you transplant in the fall, do so at least six weeks before the first hard frost.
The best time of the day to transplant a plant is in the afternoon when the sun is not as direct or bright. A cloudy or rainy day is ideal.
If it's a sunny day, a tented piece of cardboard draped over the plants will give them some respite from the sun.
Choose a location that fits the plant's needs. The amount of sun versus shade is always the most important consideration.
The soil in your new spot should be ready before the plant is dug up. Remove any perennials weeds that will rob the transplant of space and moisture.
New plant growth can be stimulated by an application of macro nutrients including phosphorus, calcium, potassium and nitrogen which are important in the formation of new tissue. It is best to supply these nutrients at the time of transplanting.
A detailed article about soil amendments can be found by clicking here.
If the soil has not completely warmed in early spring, you can place some black plastic over the top of the area and let the sunshine warm it before planting.
One of the biggest causes of shock to transplanted plants is lack of water. Good, steady watering over the first few weeks after transplanting will help the plants to settle in and allow the roots to grow down and spread out.
And since you will be watering more often, this is a great chance to make sure that your soil is draining well. Stagnant non-draining water will do more harm than good.
If drainage is a problem, add Perlite or Vermiculite to the new planting hole.
A topping of 2-3” of mulch will help to protect the plant roots from temperature variations.
To read an article about organic mulch choices for your garden, click here.
A good practice is to soak the root ball before planting it in the new spot and water regularly for the next few weeks.
Digging up the Plant
As you dig, take care to disturb the roots as little as possible. Dig up a generous amount of soil around the plant roots to keep the root ball in tact.
A bit about roots
While the thickest roots are closest to the root ball, the most important roots are the furthest from the plant. These smaller roots are the roots that take up nutrients. If too much of the root system is taken off, the plant may suffer a nutrient deficiency shortly after transplant and no amount of nutrients added after that may be able to counteract that damage.
If damaged or diseased roots need to be removed before replanting, it's a good idea to remove some of the plant's top growth also which will give the roots less leaves to support as it recovers.
A good rule of thumb is to cut back the perennial by one third. For most plants, you can generally cut back as much as half of the leaves without causing damage.
Since plants with dense foliage or large leaves are more likely to suffer from transplant shock, it is advisable to cut these back. This is a good time, too, to remove any dead branches, stems or dried leaves.
- Plant at the same depth as it was growing at.
- Space the plant appropriately to allow for good air flow. Consider the size of the plant's mature width and add 4-6”.
- After being transplanted, a plant's growth will naturally slow down temporarily and the leaves may wilt until the plant recovers. The plants at this stage are not only struggling to repair any damage caused by being transplanted, but are also trying to put on new growth.
- After your transplant is in the ground, don't forget about it. It still needs four to six weeks of care until the plant visibly bounces back. When they do, you can then treat it as you would a mature plant.
Transplanting Seedlings Into the Garden
When it comes to transplanting seedlings into the garden, the method is a bit more time consuming. You are moving seedlings or young plants that have been babbied and coddled indoors under controlled conditions and now they're going out to the unsheltered world.
Because it is the most stressful time for the plants, it is imperative that you harden off the seedlings, meaning acclimate them to the outdoors slowly.
This process is explained in detail in our hardening off article. To read it, click here.
Whether you're transplanting to grow your supply or adding new comers to the garden, a little extra effort will ensure your best chance for transplant success.