How to Protect Perennials Through Winter: Mulching, Cutting Back, and Care

ByStephen Albert

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Perennials are some of the toughest plants in the garden, but winter brings challenges in every climate. In mild zones, plants face heavy rain, cool soil, and short cold snaps; in colder regions, they must withstand deep freezes, snow cover, and repeated freeze-thaw cycles. After more than 30 years growing perennials in both warm zones like Sonoma Valley and cold climates such as Iowa Zone 5, I’ve found that winter care doesn’t have to be complicated. With a few well-timed tasks—mulching, cutting back, and simple seasonal maintenance—you can keep perennial beds healthy, protected, and ready for vigorous spring growth no matter where you garden.

Know Your Perennials Before Winter Begins

Perennials respond differently to cold:

  • Herbaceous perennials (daylilies, asters, salvias) die back naturally.
  • Evergreen perennials (hellebore, lavender, heuchera) maintain foliage but may suffer winter burn.
  • Woody perennials (rosemary, lavender, shrubby salvias) need careful pruning and mulching.

Understanding your plants helps you give each one the right care.

Cutting Back: What to Trim and What to Leave

1. Cut Back Spent Herbaceous Perennials

Cut back after frost when foliage collapses.

  • Leave 2–4 inches of stubble to protect crowns.
  • This reduces pests and disease overwintering on old foliage.

Best candidates:

  • Salvia
  • Asters
  • Coneflowers
  • Bee balm
  • Daylily

2. Leave Standing Stems for Winter Interest or Wildlife

Some perennials provide:

  • Natural winter habitat
  • Seeds for birds
  • Structural beauty in frost

Plants to leave standing:

  • Rudbeckia
  • Echinacea
  • Ornamental grasses

Cut these back in late winter instead.

3. Evergreen and Woody Perennials

Avoid hard pruning in fall.

  • Lightly shape only if needed.
  • Save major pruning for early spring to prevent cold damage.

Mulching: Your Most Important Winter Protection

Why Mulch Matters

Mulch protects perennials by:

  • Insulating roots
  • Preventing frost heave
  • Conserving soil moisture
  • Reducing weed pressure

After decades of winter gardening, I’ve found that mulch is the single most effective shield against freeze-thaw cycles.

How to Apply Mulch

  • Add 2–4 inches around perennials after the first frost.
  • Keep mulch 1–2 inches away from the crown to prevent rot.
  • Use organic mulches: shredded leaves, compost, aged bark, or wood chips.

For borderline-hardy perennials, apply a deeper layer of mulch or add straw around crowns.

Additional Winter Care for Healthy Perennials

Watering

Perennials still need occasional water during dry winter spells.

  • Water deeply when the soil is dry and daytime temps stay above freezing.

Protecting Tender Perennials

Southern California natives, borderline-hardy salvias, and Mediterranean herbs may need:

  • Light frost cloth
  • Extra mulch around the base
  • Protection from cold winds

Managing Wet Winter Soil

In heavy winter rains:

  • Improve drainage with mounded or raised beds.
  • Avoid walking on wet soil to prevent compaction.

Checking for Pests

Slugs, snails, and rodents may shelter in perennial beds in winter.
Keep mulch tidy and check crowns occasionally.

End-of-Winter Tasks

As spring approaches:

  • Remove winter mulch gradually.
  • Trim remaining stems.
  • Feed beds lightly with compost.
  • Look for new growth and divide or transplant if needed.

These early-spring steps help perennials transition smoothly into their growth phase.

Winter care for perennials comes down to observing your plants, protecting their crowns, and insulating the soil. With simple mulching, thoughtful cutting back, and a few winter checks, you can keep your perennial beds healthy and ready to burst into growth when warmer days return.

Winter Care for Cold Zones (Iowa Zone 5 and Similar Climates)

Gardening in Zone 5—where winter temperatures can drop well below freezing and snow may cover the ground for weeks—requires a different level of preparation than milder climates. When I gardened in Iowa, I learned quickly that perennials need deeper insulation, more protection from freeze-thaw cycles, and careful watching through long winter stretches. Here’s how to adapt perennial care to harsher winters.

1. Mulch More Deeply for Reliable Protection

In cold zones, mulch is not optional.

  • Apply 4–6 inches of mulch in late fall, after the ground begins to freeze.
  • Use materials that insulate well: shredded leaves, straw, pine needles, or wood chips.
  • Keep mulch slightly pulled back from crowns to prevent rot.

In Zone 5, mulch is your best defense against deep freezes and winter heaving.

2. Cut Back More Thoroughly to Prevent Disease Overwintering

Diseases persist longer in cold, wet winters.

  • Cut back most herbaceous perennials in late fall.
  • Remove diseased or mildewed foliage completely from the garden.
  • Leave only the stems you want for winter structure or wildlife.

In my Iowa beds, cutting back early greatly reduced spring disease problems.

3. Protect Tender or Marginally Hardy Perennials

Some plants hardy in Zone 7 or 8 may struggle in Zone 5.

Provide extra protection for:

  • Lavender
  • Gaura
  • Tender salvias
  • Eucalyptus (young plants)
  • Rosemary (usually not hardy outdoors)

Use:

  • Deep mulch mounds
  • Frost blankets during extreme cold
  • Temporary windbreaks on exposed sites

In Iowa, I would often mulch borderline plants almost like roses—heaping protection over crowns.

4. Guard Against Freeze-Thaw Cycles

Zone 5 winters often cycle between freezing and warming, which pushes crowns out of the soil.

To prevent heaving:

  • Mulch heavily
  • Avoid disturbing the soil in late fall
  • Check beds periodically and gently press any lifted crowns back into place during above-freezing weather

5. Protect Against Harsh Winter Winds

Cold winds desiccate evergreen perennials and shrubs.

Use:

  • Burlap windbreaks
  • Temporary fencing on exposed sides
  • Extra mulch around evergreen perennials like hellebore or creeping phlox

Wind was often more damaging in my Iowa garden than snow.

6. Snow Is Helpful—Ice Is Not

Snow acts as natural insulation in colder zones.

  • Allow snow to blanket perennial beds—it protects crowns better than mulch.
  • Avoid removing ice from plants; wait for natural melting.
  • Brush off heavy snow only from brittle shrubs or evergreens.

7. Water During Winter Thaws

Even frozen climates have dry spells.

  • During a warm stretch (above freezing), water deeply if soil is dry.
  • Plants go dormant, but roots still benefit from winter moisture.

This was especially important during windy, snowless Iowa winters.

8. Spring Cleanup Starts Later

Patience is key in Zone 5.

  • Wait to remove mulch until buds begin to break.
  • Watch for late frosts—keep frost cloth handy.
  • Don’t rake or disturb soil too early, as it compacts easily when thawing.

Spring shifts later than you expect, especially after long winters.

How This Differs From Milder Climates Like Sonoma Valley

In Sonoma Valley:

  • I mulch lightly (2–4 inches).
  • I rarely worry about heaving.
  • Frosts are shorter-lived, and winter winds are milder.

In Iowa Zone 5:

  • Mulch is deeper and essential.
  • Winter preparation begins earlier.
  • Plants need real insulation to survive long freezes.

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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