How to Overwinter Your Annuals

If your summer containers still look surprisingly lush, don't toss them out just yet. This week on the podcast, Joanne discusses how, with a little care, you can enjoy them again next year.

Tune in to learn how to overwinter your annuals.

Topics discussed:

• Many annuals are still looking great in mid-October — don’t toss them yet!
• You can successfully overwinter several annuals to save money and enjoy them again next year.
• There’s no single foolproof method; success depends on the type of plant, growing conditions, and care.
• Joanne shares three main methods: bringing the whole plant indoors, taking cuttings, and storing tubers.

Method 1: Bring the Whole Plant Indoors (Treat as a Houseplant)

• Works well for mixed containers where some plants still look healthy.
• Steps:
  • Scoop out healthy plants, repot in fresh soil.
  • Use a tray or boot tray with gravel to create humidity.
  • Lightly water (avoid soggy soil).
  • Treat with Safer’s insecticidal soap, diatomaceous earth, or Bios Nutrients herbal plant soap to remove insects.
  • Keep in a cool location with indirect light (e.g., basement or bright garage that doesn’t freeze).
  • Reduce watering through winter; keep soil barely moist.
  • Trim plants back slightly.
  • Begin fertilizing lightly again as days lengthen (Feb–March).

Examples:

• Coleus
• Geraniums (Pelargoniums)
• Million Bells (Calibrachoa) — heavy feeders; need more light

Method 2: Take Cuttings

• Ideal for plants like Coleus, Cigar Plant (Cuphea ignea), Geraniums, and others with soft stems.
• Process:
  • Take small cuttings (3–4 inches).
  • Remove lower leaves.
  • Root in water until roots form.
  • Pot rooted cuttings in small pots (3-inch) with fresh soil.
  • Use Ziploc bags or plastic covers to maintain humidity if needed.
  • Grow under indirect light or with grow lights.
• Benefits:
  • Saves space compared to bringing in full plants.
  • Allows propagation of multiple new plants.

Method 3: Save Tubers (Overwinter Dormant)

• Best for plants like Tuberous Begonias, Canna Lilies, and Dahlias.
• Steps:
  • Let the plant naturally die back (reduce watering).
  • After foliage dries up, gently remove tubers from soil.
  • Do not wash — just brush off soil and roots.
  • Allow to dry completely.
  • Store in paper bags, cardboard boxes, or vermiculite/newspaper.
  • Keep in a cool, dark, dry location all winter.
  • In late February/March, inspect tubers for rot or mildew.
  • Pot them up with fresh soil and water lightly until new growth appears.

General Tips & Insights

• This process helps extend your garden budget and reduce spring costs.
• Overwintering annuals is an experiment — expect variable results.
• Minimal maintenance: check occasionally for dryness or rot.
• Grow lights can improve success, especially for tropical plants.
• Try both full-plant and cutting methods to compare results.
• Share propagated plants with friends and neighbours!
• Think ahead when choosing annuals next spring — pick varieties worth saving.

Final Thoughts

• Overwintering annuals is low-cost and low-risk — a great winter experiment.
• Use it as a way to stay connected to your garden through the cold months.
• Even if you missed the window this year, plan to try it next fall.
• The reward: saving money, learning new skills, and keeping your garden thriving year after year.

Resources Mentioned in the Show:

Down the Garden Path: A Step-By-Step Guide to Your Ontario Garden

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Down the Garden Path Podcast

On Down The Garden Path, professional landscape designer Joanne Shaw discusses down-to-earth tips and advice for your plants, gardens and landscapes. As the owner of Down2Earth Landscape Design, Joanne Shaw has been designing beautiful gardens for homeowners east of Toronto for over a decade. She does her best to bring you interesting, relevant and useful topics to help you keep your garden as low maintenance as possible. 

In Down the Garden Path: A Step-By-Step Guide to Your Ontario Garden, Joanne and fellow landscape designer Matthew Dressing distill their horticultural and design expertise and their combined experiences in helping others create and maintain thriving gardens into one easy-to-read monthly reference guide.

Get your copy today on Amazon.

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