Keeping outdoor potted plants alive through the winter can seem daunting, but with some planning and care, it is very achievable. Here are some tips to help your outdoor potted plants not just survive, but thrive during the colder months.
Choose Frost-Hardy Plants
The first step is selecting plants that can withstand frosty conditions. Many tropical plants like hibiscus and mandevilla won’t survive outdoors once temperatures drop. Instead opt for plants like:
- Evergreen shrubs – Boxwood, holly, juniper
- Ornamental grasses – Carex, pennisetum
- Hardy perennials – Sedum, heuchera, hellebore
- Cold-tolerant annuals – Pansies, violas, ornamental kale
Choose plants rated for your specific USDA hardiness zone to give them the best chance of making it through the winter.
Use Insulating and Protective Pots
The materials and design of the pot play a big role in protecting the roots from freezing.
- Terracotta or ceramic pots allow moisture to evaporate from the sides, helping keep roots drier and less prone to rot.
- Plastic and glazed pots do not allow evaporation so are more prone to issues. However, you can insulate them by wrapping the outside in bubble wrap, burlap, or foam wraps sold for this purpose.
- Self-insulating pots are available like foam-cored fiberglass and internally insulated ceramic pots that provide a layer of insulation between the inner and outer walls.
- Elevated pots on feet or stands allow cold air to flow under, preventing root damage.
- Grouped pots provide shared warmth and protection like when overwintering in a cold frame or greenhouse.
Provide Winter Protection
Protecting the crown and roots from winter extremes goes a long way in keeping potted plants alive.
- Heavy mulching around the base insulates roots and prevents the soil from heaving during freeze/thaw cycles.
- Wrapping above ground stems with burlap secured with twine shields from winter sun and wind damage.
- Temporary cold frames or mini hoop houses maintain warmer temps and shelter from rain/snow. Ventilate on sunny days.
- Hot caps cloches, fabric row covers, and plastic sheets can be draped over plants for extra frost protection.
- For very cold regions, sinking pots in the ground or moving to an unheated garage or shed can get plants through the harshest weather.
Water and Fertilize Less During Winter
Plants grow slower and require less watering and nutrients during winter dormancy.
- Check soil moisture regularly, water only when the top few inches become dry.
- Reduce fertilizing but don’t stop completely. Apply half-strength, water-soluble fertilizer monthly.
- Avoid overwatering which can lead to root rot and leach nutrients from the soil.
- Consider using a moisture meter to avoid guessing water needs.
- If pots are wrapped, uncover periodically to check soil moisture.
Practice Good Hygiene
Prevent issues like mold, mildew, and pest infestations.
- Remove fallen leaves and other debris around pots to eliminate hiding places for pests.
- Prune away dead or damaged growth to improve air circulation and overall plant health.
- Treat any pest or fungal issues promptly before they spread. Disinfect tools after pruning infected plants.
- Keep the potting mix clean when topping off pots or moving plants.
Transition Indoors Before the First Freeze
If outdoor conditions become too extreme, be prepared to move vulnerable plants to a protected area:
- Start hardening off plants by moving them into a sheltered spot like a covered porch for a few days.
- Slowly transition indoor plants inside over 7-10 days to prevent shock.
- Identify possible overwintering places indoors near sunny windows or under grow lights.
- Repot into a slightly larger container if rootbound using fresh sterile potting mix.
With some preparation and care, it is possible to maintain healthy and attractive potted plants through harsh winter conditions. Consistent monitoring and protection are key to keeping outdoor potted plants alive and thriving into the next growing season.
Frequently Asked Questions About Overwintering Outdoor Potted Plants
What are the most important factors in overwintering outdoor potted plants?
The most critical factors are selecting cold-tolerant plants, choosing weather-appropriate pots, protecting plants from extreme cold and moisture, reducing water and fertilizer needs, and practicing preventive care against issues like pests and diseases.
How cold hardy do plants need to be for outdoor wintering in pots?
Most plants should be rated at least 2 zones colder than your actual zone to account for the extra exposure of pots. For areas with dramatic shifts like zones 5-6, choose plants rated down to zone 3-4 to be safe.
Should I wrap or cover my pots in winter?
Wrapping or insulating pots is highly recommended to regulate soil temperature and moisture. Foam wraps, bubble wrap, burlap, and other breathable materials work well. Be sure to allow for some ventilation and uncover periodically to check soil moisture levels.
When should I move outdoor potted plants inside for the winter?
In general, move tropical and semi-tropical container plants inside before night temperatures dip below 45°F. More cold-tolerant plants can stay out till around 35°F but monitor closely and bring inside before the first expected freeze.
What are good places to overwinter potted plants indoors?
A sunny window, enclosed porch, or under plant grow lights work well. Choose spots with consistent temperatures between 55-65°F. Avoid places with major temperature fluctuations or drafts. Basement and garages can work in milder climates if adequately lit.
How often should I water outdoor potted plants overwintered inside?
Check soil moisture regularly and water only when the top inch becomes dry. Water less in lower light conditions, allowing the soil to moderately dry out between waterings. Do not allow pots to completely dry out or soak from overwatering.
Conclusion
Caring for outdoor potted plants through winter’s harsh conditions is very doable with the right preparation and practices. Choosing naturally cold-hardy plants adapted to your zone and providing insulation, protection, reduced watering, and preventive care will allow most container gardens to endure and prosper. Pay close attention to your overwintered plants and be ready to shelter vulnerable ones as needed. With a little TLC, your potted plants can stay alive and come back thriving in spring.