Growing Catnip from Seed: Thinning, Pot Size, and Cat-Proofing

A gardener plans to grow 3–5 catnip plants in a sunroom and asks whether to thin seedlings to one per pot, and what pot size (4–6 inches) is best.

Seed Starting and Thinning

1. Sow seeds on moist seed-starting mix in a shallow tray. Barely cover.
2. Cover with plastic wrap; keep at 70–75°F in indirect light.
3. Germination: 7–14 days. Remove cover immediately when sprouts appear.
4. Thin to one seedling per cell or 3-inch spacing. Crowded seedlings become leggy and disease-prone.
5. When seedlings have 2–3 true leaves, transplant each into its own 4-inch pot.

Pot Size and Up-Potting

• Start in 4-inch pots. This size balances root development with space efficiency.
• Up-pot to 6–8 inches when roots fill the container (usually 4–6 weeks).
• Mature plants thrive in 10–12 inch pots or larger if space allows.
• Ensure pots have drainage holes. Use well-draining potting mix with perlite.

Critical: Protect from Cats Until Established

Cats will destroy young catnip. Keep plants completely inaccessible (high shelf, closed room, wire cage) until they reach 12–18 inches tall with woody stems. Only then can they withstand browsing and regrow.

Sunroom Care

• Light: 6+ hours direct sun. South/west window ideal.
• Water: When top inch of soil is dry. Don't overwater.
• Fertilize: Monthly with balanced organic liquid fertilizer.
• Harvest: Cut stems above a node. Dry for cat toys or tea.

With proper thinning, potting, and cat-proofing, you'll have a thriving, sustainable catnip supply.