In the fourth episode of Down the Garden Path's "Houseplant Chat" series, Joanne discusses the basics of fertilizing houseplants.

Topics Covered

• When to start fertilizing
  • Wait until days are noticeably longer (sometime after daylight savings time) when plants begin active growth again.
• How to read fertilizer labels (N-P-K)
  • The three numbers represent Nitrogen (N), Phosphorus (P), Potassium (K).
  • Leafy plants may benefit from higher nitrogen; flowering plants often need more phosphorus.
• Choosing an "all-purpose" fertilizer
  • Balanced blends (e.g., 10-10-10) can work for many houseplants, especially as a baseline.
• Three common fertilizer formats
  • Water-soluble liquid: mix into watering can; easy to apply while watering.
  • Granular: sprinkle on the soil surface; dissolves as you water (Joanne notes it can feel less precise).
  • Slow-release pellets: dissolve gradually; may only need reapplying every few months.
• Frequency & control
  • Liquids are immediate and routine-friendly; granular and slow-release can be less frequent but require awareness of plant needs.
• Start gently
  • Use half-strength for the first few feedings at the start of the season to ease plants in.
• Organic vs. big-box options
  • Joanne prefers organic options (often lower N-P-K numbers) and mentions the appeal of local/smaller brands, while acknowledging "use what you have" if it's already in your cupboard.
• Check expiry dates
  • Expired fertilizer is usually not harmful—just potentially less effective.
• Know your special plants
  • Spot-check care requirements for "can't-risk-it" plants: heirlooms, cuttings, orchids, sentimental favourites (she shares the example of a long-loved rubber tree).
• Homemade fertilizer recipes (with caution)
  • DIY approaches (tea/coffee grounds/fish emulsion) exist, but beginners should stick to products with known N-P-K values.

Takeaways and Tips

• Don't rush it: Start fertilizing when daylight increases (typically after daylight savings), not in the dead of winter.
• Half-strength first: For the first few fertilized waterings, go 50% strength to avoid shocking plants waking up from slower winter growth.
• Match fertilizer to the goal:
  • Leaf growth: consider a more nitrogen-forward option.
  • Flowering: look for a higher middle number (phosphorus).
• Pick a method you'll actually remember:
  • If you're consistent with watering, liquid can be easiest.
  • If you forget steps easily, slow-release may be safer; just add a reminder so it doesn't get missed.
• Follow the label (seriously): Package directions matter more than brand debates.
• Research your "VIP plants": If a plant is sentimental or pricey, do a quick care check so you're not guessing at feeding needs.
• Use what you have, smartly: If you find old fertilizer, check the expiry date; it may still work, just a bit weaker.
• Keep it measurable: If you're newer to houseplants, prioritize fertilizers with clear N-P-K numbers over DIY mixes until you've got a baseline routine.

Other Houseplant Chat episodes

Getting the Light Right

Soil and Watering Tips

Propagation Made Simple

Have a topic you'd like Joanne to discuss?

Email your questions and comments to [email protected], or connect with Joanne on her website: down2earth.ca

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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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