Bare-root versus container stock: does gel change the transplant shock number

Three hundred and forty bare-root hawthorn whips went into a windbreak in late November. By the following August, 61 were dead: 18 percent. Two hundred metres away, 340 container-grown whips of the same species, planted the same week by the same crew, lost 11. Both blocks had gel in the backfill at the same rate. The interesting number is not the gap between 18 and 11. It is what happened in the sub-block where the crew dipped the bare-root roots in gel slurry before planting, which lost 27 percent.

That result runs against the way most people think about transplant shock, and it is worth unpacking before anyone else buys a bag of powder to make a slurry.

The two stocks lose water in different places

A container plant arrives with a root system that is intact but circular, sitting in a media that holds water far better than the surrounding soil. Its shock comes from the interface: the roots do not want to leave the pot-shaped media, and water movement across that boundary is poor for weeks. Bare-root stock arrives with no media at all, a root system that has been lifted and stored, and a desiccation clock that started at lifting.

Gel placed in the backfill addresses the interface problem well. It keeps the surrounding soil at a moisture level closer to the root ball, which encourages roots to cross out. That is why container stock responds consistently, and why the response is biggest in the first six weeks.

Bare-root stock has a different problem. The fine roots that do the absorbing are the ones most easily killed by exposure, and they are already dead or dying by the time the tree reaches the hole if the chain from lifting to planting has gaps.

Where the slurry idea goes wrong

The gel dip sounds sensible: coat the roots, keep them moist, plant. In practice, a slurry tank becomes a place where roots sit in the sun while a crew works through a bundle, and where the coating dries on the roots within minutes once they come out. A dried gel coating on a fine root is a film. It does not rehydrate quickly, and it does not help the root absorb anything.

In the block that lost 27 percent, the bundles were dipped at the trailer, stacked in the shade for up to forty minutes, then carried out on a barrow. The gel on the outer roots dried to a crust before the trees reached the hole. The control rows, planted dry with gel only in the backfill, did better. That is the result that surprises people: a step which looked like extra care made the outcome worse.

If you do dip, the rules are strict. Dip immediately before planting, one bundle at a time, keep the bundle covered, and never let a coated root see sun. Most crews cannot hold that discipline across a long day, which is why I usually recommend against dipping as a standard practice.

What actually moved the number

In both blocks, the strongest predictor of survival was not the stock type and not the gel rate. It was the number of days between lifting and planting. Trees planted within 48 hours of lifting survived at 94 percent regardless of type. Trees planted on day five or later survived at 79 percent, and no amount of backfill gel closed the gap.

The second predictor was planting depth relative to the original nursery line, and the third was whether the hole was watered at planting. Gel that is dry when the tree goes in does not help a tree that is also going in dry; the first irrigation has to serve both.

A fair way to compare the two

If you want to know whether gel changes the shock number for your own stock, set up four rows rather than two: bare-root with gel, bare-root without, container with gel, container without, twenty plants each, same day, same crew, same soil. Record survival at 6, 12 and 26 weeks, plus the date of each irrigation. Twenty plants per treatment is small, but four treatments on one site in one season will tell you more than a supplier demonstration ever will.

Expect the container rows to show a modest, consistent benefit. Expect the bare-root rows to be noisier, because their outcome depends heavily on handling before planting, which is the variable you are least able to control once the trees leave the nursery.

For container stock: gel mixed through the backfill at the label rate, hole watered at planting, and no reduction in irrigation for the first six weeks. For bare-root: skip the dip, mix the gel through the backfill, plant within 48 hours of lifting if you can, and spend the money you saved on a shade cover for the bundles.

If you are specifying both types on one contract, the application guide sets out the mixing method for each, and the difference in the first irrigation matters more than most people expect.

Send us the species, the lifting date and the soil type before your next bare-root order and we will tell you whether gel in the backfill is likely to earn its cost on that block, or whether your money is better spent on cold storage.