Wind rock

What you are looking at

A shrub, a young tree or a tall brassica has a funnel-shaped hole in the soil around its stem, a few centimetres deep and wider at the top. Push the stem and the whole base moves rather than the top flexing.

After rain there is water sitting in that hollow.

Above ground the plant is yellowing, growing slowly and generally sulking on ground where everything else is fine.

Brussels sprouts and kale show it best. By midwinter on an exposed plot they are leaning at an angle, the sprouts have blown open, and there is a socket around every stem.

The hole is what does the damage

The rocking itself tears the fine roots that a plant needs to feed and drink with, which is enough on its own to check growth.

The hole is worse. It funnels rain straight down to the collar of the plant and holds it there, so the base of the stem sits in water through the winter. Collar rots and phytophthora both get in exactly there, and a great many plants recorded as dying of root rot were rocked first.

That is why filling the hollow matters as much as firming the soil. Two minutes with a heel and a spadeful of soil, done in November, prevents both the tearing and the puddle.

Staking, and how it usually goes wrong

A newly planted tree needs its root ball held still while the roots grow out into the surrounding soil. It does not need its trunk held still, because a trunk that flexes in wind lays down the wood that makes it strong.

So the stake goes in low, at about a third of the tree’s height, angled or vertical, with a single tie fitted loosely. That holds the roots and lets the top move.

The usual mistake is a tall stake with the tie near the top, left in place for ten years. The tree grows a slender trunk that has never had to support itself, the tie cuts into the bark as it thickens, and when the stake finally rots the tree goes over in the first gale.

Fit it low, check the tie annually, and take the stake out after two or three seasons.

What to do about it

Walk round after a gale and check anything tall for a socket at the base.

Tread the soil back firmly, fill the hollow so water cannot stand in it, and water it in.

Plant Brussels sprouts, kale and sprouting broccoli deep and firm them hard.

Earth up the stems of tall brassicas and leeks in autumn.

Cut leggy roses and buddleja back by about half in November, and do the real pruning in spring.

Stake new trees low, tie loosely, check yearly, and remove the stake after two or three years.

Support dahlias, sunflowers and sprouts before the weather rather than after it.

Keep mulch off the collar.

Plant a hedge rather than a solid fence where wind is the problem, since a hedge filters wind and a fence creates turbulence behind it.

What it gets mistaken for

Waterlogging affects the whole bed rather than producing a private puddle around one stem.

Root rot is frequently the cause of death and wind rock is frequently the reason it got in.

Transplant shock stalls a newly planted shrub that is nonetheless firm in the ground.

Vine weevil and other root pests stall a plant and leave the soil around the stem undisturbed.

Honey fungus kills from the base with white sheets under the bark and bootlaces in the soil, and a rocked plant is more vulnerable to it.