A Heave and a Ho: Protecting Plants from Frost Heave

Early spring, when the earth is beginning to warm again, I love walking in the forest behind my house. Underfoot the ground is squishy. It feels like...

  • Topic: Winter Care
  • Author: Cindy Bellinger
  • Keywords: frost, winter, soil, freeze, thaws, heave, temperatures, roots, winter damage
  • Date: January 1996

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Early spring, when the earth is beginning to warm again, I love walking in the forest behind my house. Underfoot the ground is squishy. It feels like walking on foam.

But this soft foaminess is because of frost heave, a condition that occurs when water remains in the soil and freezes. It brings submerged rocks to the surface and leaves the soil powdery. It’s nature’s way of aerating the ground.

The same process takes place in our gardens and if we don’t take care, frost heave can kill some of our favorite plants.

When soil repeatedly freezes and thaws, the pushing and turning can fracture roots—taproots as well as lateral roots. The heaving activity can also result in elevated crowns, pushing a plant up slightly, making it dry out. Plants subjected to any of this will either die or be severely stunted.

Drain Soil

To prevent damage from frost heave both surface and subsurface drainage is essential to plants for winter survival. Adding organic matter helps loosen soil and loosened soil drains water. Our clay soil in the Santa Fe area retains water so loosen it up, let it drain. Roots of xeric plants that sit submerged in water will rot. Set plants slightly above the soil level in low-lying areas.

Moderate Temperatures

Frost heave occurs when temperatures are inconsistent, especially as we approach the dead of winter. When the ground remains frozen, heave doesn’t occur. It’s when the ground starts to thaw that problems occur.

Mulch often helps take care of temperature inconsistencies. But keep mulch away from the crown of plants, where the stems and stalks grow. The crown needs to breathe and be free to dry out.

Watering

Though it’s important to continue watering during the winter, excessively wet soil can decrease winter hardiness in some plants. When surrounded by standing water, plants will wilt. It sounds like a paradox but water-laden roots are unable to gather water, which therefore starves the plant for oxygen and other nutrients.

Freezing is the most common cause of winter damage in a garden, and the plants most susceptible to heaving are newly planted ones because their roots aren’t sufficiently anchored. If a plant does pop out, just push it back in. And, of course, hope for the best.

The difference between noticing the result of frost activity in a forest and in my garden is tremendous. In a forest I marvel at all that takes place. With my garden, I fret. Guess it’s all part of this thing called gardening.