Keeping Petunias Through Winter: A Guide to Overwintering Petunias

Petunias are a classic summertime flower, gracing gardens and porch planters with their colorful blooms. But when cold weather hits, these warm-season annuals normally perish. With proper care, however, you can successfully overwinter potted petunias indoors and replant them the following spring.

Why Overwinter Petunias

Letting petunias die off when winter comes is common practice. But for gardeners who want to retain favorite plants from season to season, overwintering is worthwhile. Here are some key reasons to keep petunias through the winter:

• Saves money instead of buying new plants every year Some hybrid petunias can cost over $5 per starter plant,

• Maintains access to sentimental or rare varieties you want to preserve.

• Allows you to reuse large container plants. It’s wasteful to compost huge potted petunias still in their prime.

• Provides an early jump on spring gardens. Overwintered plants adapt quickly when moved outside.

• Offers mental health benefits of having living plants indoors during dreary winter

Best Candidates for Overwintering

Almost any petunia can be overwintered, but some are better choices than others:

• Potted patio plants vs. in-ground – Container plants are easier to move and care for indoors.

• Non-patented varieties – Propagating patented plants from cuttings is illegal.

• Premium plants worth the effort – Focus on saving expensive or special hybrids.

• Healthy, pest-free plants – Weak or infested plants may not survive indoors.

• Established plants from early summer – Older plants overwinter better than late plantings.

Transitioning Plants Indoors

To successfully overwinter potted petunias:

• Bring plants inside before the first frost, when temperatures drop below 40°F at night.

• Check for pests like aphids before bringing indoors. Treat with insecticidal soap if found.

• Prune back plants by 1/3 to 1/2 to remove dead growth and shape the plant.

• Water thoroughly and allow to drain before moving inside.

• Place in a bright, sunny window where temperatures stay above 55°F.

• Allow 1-2 weeks for plants to adjust before fertilizing or repotting.

Ideal Overwintering Conditions

Petunias need the following conditions for healthy winter maintenance indoors:

• Temperatures: Consistently above 55°F. Avoid drafty areas.

• Light: South-facing window or supplemental grow lights.

• Water: Allow soil to dry out partially between waterings.

• Humidity: Moderate 40-60% humidity. Mist leaves if too dry.

• Fertilizer: Use houseplant formula at 1/2 strength every 2-3 weeks.

• Pruning: Remove dead growth and shape occasionally. Don’t cut back hard.

• Pests: Watch for aphids, whiteflies, fungus gnats. Use organic controls if found.

Overwintering Special Considerations

• Petunias require 14+ hours of daylight, so keep grow lights on a timer.

• Repot rootbound plants in fresh potting mix to stimulate growth.

• Take cuttings in late winter to replace any plants that weaken or die off.

• Avoid overwatering during periods of dormancy when growth slows.

Moving Petunias Back Outside

In early spring after the last frost date, begin transitioning petunias back outdoors:

• Move to a sheltered, shaded spot for 1-2 weeks to adapt.

• Check for any pests before taking plants outside.

• Give plants a light trim to shape and remove any dead growth.

• Ensure potted plants have adequate drainage holes before placing outside.

• Gradually expose plants to more sun over a week or two to harden off.

• Transplant into beds or containers after 2-3 weeks of hardening off.

• Water thoroughly and feed with a balanced fertilizer to stimulate new growth.

Overwintering Petunia Cuttings

An alternative to keeping whole plants is taking cutting in fall and rooting them to grow new starter plants:

• Take 3-5 inch tip cuttings from healthy plants in late summer.

• Remove lower leaves and place in pots filled with sterile potting mix.

• Keep soil moist and cuttings will root in 2-3 weeks in warmth.

• Grow on windowsill over winter. Transplant outside next spring after hardening off.

Enjoy Continuity in Your Garden

While requiring some effort, overwintering lets you restart your garden with mature, vigorous petunia plants already adapted to your conditions. You can continue growing treasured varieties year after year. With the right indoor care, petunias can grace your indoor spaces through dreary winter months and return to the garden ready to thrive when summer comes again.