Forcing Bulbs Indoors: Winter Colour in 10 Weeks

Forcing is the practice of tricking spring bulbs into flowering months early, indoors. It requires no special equipment — a cool dark space and a windowsill will do.

The principle

Spring bulbs need cold to break dormancy, then warmth to grow. Forcing simply compresses that cycle into a controlled sequence: 12 weeks of cold, then 3–4 weeks of warmth.

Which bulbs force well

• Hyacinths — the best choice. Fragrant, compact, and reliably floriferous.
• Paperwhite narcissi — need no chilling at all; 4–6 weeks from potting to flower.
• Standard narcissi — need 12–15 weeks of cold.
• Crocus — 10–12 weeks cold; charming in shallow bowls.
• Tulips — 14–16 weeks cold. Slower, but worth it.

Avoid bulbs sold for outdoor planting that have already been pre-chilled for garden use if you want precise timing — buy forcing-grade bulbs where possible.

Potting

1. Use clean pots with drainage holes and free-draining compost.
2. Set bulbs close together, almost touching, with the tips just at the surface.
3. Top up with compost to the bulb necks, leaving a 1 cm watering gap below the rim.
4. Water thoroughly once.

The cold phase

Move pots to a dark, cold place: 5–9°C. A garage, cellar, unheated porch, or a refrigerator for small pots. Darkness matters — light during chilling produces pale, drawn stems.

Check every two weeks. Keep the compost barely moist, never wet. Roots should appear at the drainage holes within 6–8 weeks.

The warm phase

When shoots are 5 cm tall, bring pots into a cool, bright room at 15–18°C. Too warm, too fast, and stems stretch and flop. Full sun at this stage also bleaches the flowers.

Water more freely now. Turn pots every few days so stems grow straight.

Timing chart

• Flowers in late December: pot early October, chill 12 weeks, warm from mid-December.
• Flowers in mid January: pot late October.
• Flowers in February: pot mid November.
• Paperwhites for Christmas: pot early November, no chilling, keep cool and bright.

After flowering

Forced bulbs are exhausted. Most people compost them. If you want to keep them, plant outdoors after the last frost and accept that they may skip a season before flowering again.

Troubleshooting

• No roots after 8 weeks: too dry, or bulbs were stored badly.
• Long pale stems: too warm during chilling, or light too low during growth.
• Mould on compost surface: poor air circulation — increase ventilation and water less.

Choose forcing-grade hyacinth bulbs and narcissus bulbs from our shop.