Perennials

Check perennials for frost heaving.

Frost Heaving Perennial

Later this week several days of snow-melting temperatures are in the forecast in the Midwest. Take advantage of this opportunity to check the perennials in your garden for frost heaving.

Frost heaving is caused by repeated periods of freezing and thawing temperatures. With each freeze the water in the soil expands; with each thaw it contracts. These alternating conditions may force plants up and out of the soil.

Frost Heaving Perennial in Rock Garden
Frost heaving exposes roots to freezing temperatures and drying winds.

Some roots are broken as they are heaved from the soil; more are damaged when they are exposed to freezing temperatures and cold, drying winds.

If you notice some plants have succumbed to frost heaving, take corrective action to minimize damage. Try to press plants back into the soil, but be gentle. Pushing too hard or treading heavily can cause soil compaction.

Boughs Covering Perennials
Evergreen boughs are an ideal choice for covering perennials.

After plants are back in place, cover them with straw, shredded leaves or other loose mulch. Evergreen boughs left from holiday displays are an ideal option.

If plants can’t be eased back into the soil and roots remain exposed, add soil or mulch to cover them. Be careful not to cover the crowns of plants with soil. Instead, use your choice of loose mulch as above.

Heuchera 'Paris'
Coral bells like this Heuchera ‘Paris’ are prone to frost heaving.

Some perennials are more apt to frost heave than others. Perennials planted too late in the fall for their roots to take hold are prime candidates for frost heaving. Plants with shallow root systems are also usual suspects. Some examples of these are pigsqueak (Bergenia), blanket flower (Gaillardia), coral bells (Heuchera), foamy bells (Heucherella), Shasta daisy (Leucanthemum), pincushion flower (Scabiosa) and foamflower (Tiarella).

Strawberry Plant with strawberries
Strawberries are shallow rooted and often frost heave.

Check the strawberry patch, too. Strawberries are also shallow rooted and known to frost heave.

When you are planting next season, take measures to minimize frost heaving:

  1. Add lots of organic matter to the garden to improve the drainage of the soil.
  2. Make sure there is a two to three inch layer of mulch around perennials. Mulch reduces temperature fluctuations in the soil.
  3. Be sure all fall-planted perennials are in the ground at least six weeks before the first frost so their roots have plenty of time to secure themselves in the soil.

Enjoy the winter walk through the landscape. Garden with me!

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