Overwintering Plants: A Pacific Northwest Guide

Overwintering plants doesn’t get nearly enough attention, especially in spring, when we’re all thinking about summer. But once the rain and cold roll back in, those new plants you just put in the ground (or in pots) might need a little help to make it through. Here are some straightforward tips to get them ready before winter really hits.

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The PNW Problem: It’s Not Just Cold, It’s Wet

Around here, the bigger threat isn’t always the freeze, it’s the nonstop rain. Most plants, especially bulbs, while they’re dormant, hate sitting in waterlogged soil. That’s why well-draining soil is non-negotiable, especially in containers.

When you plant, break up that heavy clay soil and mix in compost or other organic matter. The goal? Let water move through. A little moisture is fine—standing water is not.

Potted Plants Take a Bigger Hit

Here’s the thing: a plant in a pot is 1 to 2 hardiness zones less tough than the same one in the ground. Pots just don’t insulate as well as soil.

So what can you do?

• Bring pots into a garage, shed, or greenhouse.
• Dig a hole and sink the whole pot in the ground—it’s like giving it a cozy blanket, and you can pop it out in spring.
• Wrap pots in burlap, bubble wrap, or frost cloth.
• Group them together and pile mulch or leaves around the base.

And about the pots themselves: Bigger is better—they hold heat longer. Clay or terracotta handles temperature swings better than plastic (though plastic won’t crack when it freezes and thaws).

In-Ground Plants? Mulch Is Your Best Friend

For plants in the garden, mulching is the easiest, most effective thing you can do.

Don’t use fresh grass clippings by themselves, they mat down and trap water. Mix them with leaves or chips if you want to use them. 

For extra-tender plants during a cold snap:

• Drape frost cloth or burlap over them.
• Use stakes or a simple wire cage so the fabric doesn’t touch the leaves.
• Keep it dry—wet fabric can freeze right onto the plant.

It All Comes Down to the Roots

Here’s what matters most: protect the roots. The top growth might die back—totally normal. It’ll come back in spring. But if the roots freeze solid or rot from too much water, the plant is done. Everything it worked for all season is stored in the roots, keeping it alive through winter.

Quick Winter Prep Checklist

• Use well-draining soil (especially in pots)
• Remember: potted plants drop 1–2 hardiness zones
• Mulch in-ground plants with 3–4″ of organic material
• Go for larger clay or terracotta pots when possible
• Cover tender plants—keep fabric dry and off the foliage

Do these few things, and your plants will wake up happy and ready to grow when spring finally shows up.