Transplant Shock: 10 Ways To Minimize Transplanting Shock

Growing vegetables, flowers, shrubs and trees from seeds and cuttings is so rewarding. But transplant shock can take the fun out fast, when a plant you just moved sits there and sulks, or worse, never recovers.

Plants are built to stay put. They send roots out deep or wide and stay there. When we move them, we tear some of those roots and drop the plant into new soil, new light and new wind all at once.

The good news? When care is taken to reduce stress during transplanting, plants are likely to recover rapidly. The steps are simple. Here’s what actually works, and the popular “shock tonics” you can skip.

What Causes Transplant Shock?

Transplant shock is the stress a plant goes through after it is moved. Montana State University Extension says compromised roots are the primary cause, and lists leaf scorch, wilting, reduced leaf size and chlorosis (yellowing) as symptoms, along with delayed growth. The University of Kentucky adds canopy thinning, branch dieback, poor leaf color, premature fall color and early leaf drop to the list.

Why the roots? The tiny root hairs do the work. Plants take up water and nutrients through root hairs, which are so small you generally can’t see them. Dig a plant and many of them stay behind in the old soil. Field-dug trees go into the ground with reduced root systems, and when a big share of the roots is lost, the plant’s ability to take up water drops sharply.

That’s why every tip below comes back to the same two things: protect the roots, and keep water coming until new ones grow.

10 Tips On How To Prevent Transplant Shock

1. Buy Healthy Plants

Start with a plant that is ready for the move. Before buying a new plant, look it over closely. Buy only healthy, hardy plants: weakness from earlier stress, insects or disease is one of the causes of transplant shock. Skip plants with obvious pests, spots, or wilting.

Check the roots too. Slide the plant out of its pot if the garden center allows it. A plant that is badly root-bound, with roots circling the pot, can keep circling after planting. If you do bring one home, see tip 5 for how to loosen those roots.

2. Harden Off Seedlings First

Seedlings raised indoors have never felt full sun, wind or a cold night. Move them straight to the garden and University of Vermont Extension says they would likely be scorched and shocked by the change.

The fix is to harden off your seedlings. Here are the steps:

• Start a couple of weeks before you plan to plant out.
• Begin with an hour or two outdoors in a sheltered spot, early in the morning or late in the evening.
• Leave them out a little longer each day. If they wilt or flop, bring them back in until the next day.
• Cut back slightly on watering during this time.
• If you must rush, give them at least one week.

Here’s why it works: lowering the temperature or holding back some water thickens the cuticle, the plant’s waxy outer layer. And the longer the flats have been outside, especially overnight, the less shock the transplants have to withstand.

3. Know When To Transplant

Timing has two parts: the season and the day.

The season. For trees and shrubs, the ideal times are during dormancy, after leaf drop in autumn and before budbreak in early spring. Autumn planting gives new roots more time to establish before hot, dry summer weather. Early spring may be preferred in very cold winters, and it is the recommended time for broadleaf evergreens such as hollies, boxwoods and rhododendrons. Plants grown in containers can go in through the growing or dormant seasons.

Here in Florida the rules shift. UF/IFAS Extension says the worst time to plant shrubs is when the weather is both hot and dry, and suggests planting at the start of your local rainy season if you can’t water regularly.

Some plants have their own calendar. Move conifers and deciduous trees in fall, but transplant cacti during their summer growing season.

The day. For vegetable transplants, pick a cloudy, wind-free day, or late in the afternoon as the sun begins to set. Avoid very hot weather and plant in the evening so the plants get a cool night; the best time of all is just before a stretch of rainy or overcast days.

4. Keep The Roots Intact And Moist

Every root you save is one less root the plant has to regrow.

• Soak first. The University of Georgia says to thoroughly soak seedlings in their flats before you transplant, so the soil and roots hold together.
• Keep the soil on the roots. Keep as much soil as you can around the root ball. This protects the root hairs and helps the plant get over transplant shock faster. Don’t shake the soil off.
• Handle by the leaves or root ball, never the stem. Grabbing a seedling by the stem is like holding someone by the neck.
• Dig the new hole first. Have the hole ready before the plant comes out of its container, to cut the time the roots are exposed.
• Never let the roots dry out. A root ball allowed to dry out before planting is a cause of transplant shock. For bare-root plants, soak the roots in water for up to 30 minutes before planting, but don’t leave plants standing in tubs of water.

Moving an established tree or shrub? Root prune ahead of time. Start root pruning six months before the move: mark a circle the size of the root ball you want, dig a trench just outside it, then backfill and water the trench to provide moisture for new root development, and move the plant at the right time of year. Smaller stock is also less susceptible to transplant shock.

5. Plant At The Right Depth In The Right Spot

No matter how careful the move, poor planting adds stress. Start with the right plant for the site. Check your plant’s mature size, soil, pH, water and light needs, and if the site doesn’t match, don’t plant it there.

Then plant it well:

• Dig wide, not deep. Dig a shrub hole at least one and a half times wider than the root ball and an inch or two shallower; for trees, two to three times the width of the root ball. Advice varies, though: some guides say twice as wide as the root ball, at the same depth.
• Find the root flare. That’s the point where the top root joins the trunk. It should sit even with or slightly above the soil surface, and most people plant shrubs too deeply. Excessive planting depth is a major cause of transplant shock and plant death. More on why in our article on a buried root collar.
• Loosen root-bound roots. For a root-bound container plant, cut or pull the circling roots apart, or make vertical cuts about one inch deep in 4 to 6 places around the root ball. If the plant isn’t root-bound, there’s no need to disturb the roots. For trees, you can shave off the outer inch or so of the root ball.
• Remove wrappings. Remove nursery tags and wire, containers, wire baskets and burlap, since synthetic burlap does not decay and roots can’t break through.
• Backfill with the soil you dug out. Don’t add compost or other amendments to the planting hole. If the soil needs help, amend the whole bed instead.

Vegetables follow the same idea. Set a seedling at about the same level it grew in its tray. Tomatoes and peppers are the exception: they can be planted much deeper, and roots will grow along the buried stem. See our tips on transplanting tomato seedlings.

Related: You may like our article on Dividing Transplanting Tips.

6. Water Plants Carefully

This is the big one. Supplemental watering is the single most important method for preventing transplant shock, and plain old water is often the most important factor in transplant success.

At planting. Put back about half the soil, water, then finish filling the hole, so the water reaches the root zone rather than the surface. Make sure the root ball and surrounding soil are very wet, and add soil if it settles. Saturating the root ball and some of the native soil around it encourages new roots to spread out.

After planting. How often depends on the plant and your climate, and the sources differ:

• Vegetable transplants: young transplants need watering for the first three or four days until they become established.
• Shrubs in Florida: Light, frequent watering is more efficient and effective than large, infrequent soakings. A shrub from a 3-gallon pot can be established with as little as one gallon every eight days north of Orlando and every four days south of Orlando, applied right to the root ball. Even a single guide can give two establishment times for shrubs: about 5 to 7 months in one section, and about 20 to 28 weeks in another.
• Trees in Florida: Water trees planted in spring or summer two to three times a week, then weekly after the first few months until established, using 2 to 3 gallons per inch of trunk diameter.
• Trees and shrubs in Kentucky: new transplants need at least 1 to 2 inches of rainfall per week. Give the whole root zone a thorough soak every 7 to 10 days during dry periods, and skip frequent light sprinklings, which encourage shallow roots.

Don’t overdo it either. Daily watering can amount to “killing the plant with kindness,” and heavy soils drain poorly, so take care not to overwater them. Cacti are their own case: trim off damaged cactus roots and let the cuts dry and scab over for two or more days before planting.

How long should you keep it up? One year of supplemental watering is common for transplants to re-establish, and longer for plants that are not drought adapted.

7. Mulch, But Keep It Off The Trunk

A layer of mulch holds moisture in the soil around new roots. Mulch reduces evaporation around new transplants and keeps the soil cooler.

Where you put it matters as much as using it. Use 2 to 3 inches of organic mulch such as bark, wood chips or pine straw over the root zone, kept back 2 to 3 inches from tree trunks, and no “volcano” piles against the trunk. Black plastic should not be used as mulch, because roots under it can be starved of oxygen. Trees can use more room: a circle at least 8 feet across, 3 inches deep, with a 12-inch gap between the trunk and the mulch. For shrubs, keep mulch at least 2 inches from the stems and off the top of the root ball. More in our guide to landscape mulch.

8. Prune Only Dead, Broken Or Diseased Wood

You may have heard you should cut back the top of a new transplant, by as much as half, to “balance” the roots it lost. Research under landscape conditions doesn’t back that up.

Washington State University horticulturist Linda Chalker-Scott says research under landscape conditions shows pruning at transplant is not necessarily beneficial and may even harm the tree. Her reasoning: cutting off growing tips triggers new shoots, which pull resources away from root growth, and fewer leaves means less photosynthesis. Her bottom line is that there is no need to top-prune landscape plants if they will be watered after transplanting.

It is usually not necessary to reduce canopy size at planting, because leaves make the sugars that fuel new roots. Excessive pruning of newly planted trees will increase stress.

What should you cut? Dead, damaged and diseased limbs, plus structural corrections on young trees, using thinning cuts rather than heading cuts.

9. Skip The Transplant Tonics

Garden centers sell plenty of products promising to “prevent transplant shock.” Here’s what the research says.

Vitamin B1. Applying vitamin B1 (thiamine) to the roots of whole plants does not stimulate root growth or reduce transplant shock outside the lab, and one study found more root growth with plain water than with thiamine. Healthy plants make their own. The University of Arizona reaches the same conclusion: studies on woody plants, annual flowers and crops failed to show any growth response.

Root stimulators. Some of these also contain auxins, plant hormones such as IBA and NAA. Auxins have had some success regrowing roots on transplanted trees, while vitamin B1 on its own does not stimulate root growth. Hard-to-transplant species may be helped by auxin-containing products, but read the label and don’t add unnecessary chemicals.

Epsom salt. A review of Epsom salt claims found no scientific research supporting mixing it into garden soil before planting, and there is no reason to add it unless the garden has been intensively cropped or a soil test shows a magnesium deficiency.

Sugar water. The evidence is thin. Two field trials on young birch trees, published in the journal Arboriculture & Urban Forestry, found that some sugar drenches increased root and shoot growth after severe root pruning. The researchers say further research is required for other tree species and for landscape-sized trees, and that the practicality of weekly applications still needs to be addressed. That’s a long way from a proven fix for your garden.

Fertilizer at planting. For trees and shrubs, it is not necessary to fertilize at planting time or during the first year, and excessive fertilizer at planting can cause root “burn.” Fertilizer at planting is generally not recommended for woody or native landscape plants. If you do feed landscape plants, a nitrogen fertilizer is adequate; avoid “transplant fertilizers” that contain phosphate.

Vegetables are treated differently. Watering in transplants with a high-phosphorus, water-soluble fertilizer can help them get off to a good start, especially in early spring when the soil is cool. If you use one, follow the label rate.

10. Keep An Eye On Transplants

A stressed plant is an easy target. Secondary insect and disease problems are among the symptoms of transplant shock, and stressed transplants are more vulnerable to disease and insect infestations.

Check new plantings every few days. Look for wilting, pests and dry soil, identify any bug before you treat it, and adjust your watering as the weather changes.

How Long Does Transplant Shock Last?

It depends on the plant. Young vegetable transplants need watering for the first three or four days, until they become established. For shrubs in Florida, there are two figures: about 5 to 7 months, and about 20 to 28 weeks.

Trees take much longer: woody plants may take as long as 3 to 5 years to establish and recover from transplant stress, and new leaves and shoots are not a sign of establishment. A transplant isn’t established until its roots grow out into the surrounding soil. Woody ornamentals can take up to five years, depending on the size of the tree.

So be patient. Keep watering through that first year, keep the mulch in place, and let the roots catch up.

With these ten tips, your plants will be on their way to less transplant shock, and you’ll keep the fun in growing! What’s the hardest plant you’ve ever moved? Tell us in the comments.

Recommended Reading

• Sorry! – This Is The Best Plant Tip I Never Shared
• Tips on When To Thin Seedlings