Bulb | Flower | Winter | Spring |

Artificially speeding up a plant’s growth, flowering or fruiting, usually by manipulation of temperature and light. Rhubarb and chicory can be forced in late winter by covering with a forcing jar or bucket, or by placing potted plants in the dark, to produce earlier, paler, sweeter growth. Hyacinths and other spring bulbs are often forced, so they flower earlier indoors.

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Preparation

Most spring-flowering bulbs need a sustained period of cold temperatures to stimulate growth. Bulbs planted outdoors are naturally chilled by winter soil temperatures. Indoors, we can replicate these temperatures by chilling bulbs in a cold, dark place before moving them into the warmth. This technique is known as 'forcing' bulbs and it prompts them to bloom indoors during winter instead of spring.

You can either buy 'prepared' bulbs (pre-cooled by suppliers) or chill unprepared bulbs yourself in a fridge, unheated shed or sheltered dark outdoor spot. The location must be frost-free.

Here are our suggestions for easier growing:

• Hyacinth (Hyacinthus): 8-10 weeks of chilling in a cold, dark place, followed by about 3 weeks in the warmth to flower
• Paper-white daffodils (Narcissus): 6-10 weeks of chilling in a cold, dark place, followed by 5-6 weeks in the warmth to flower
• Amaryllis (Hippeastrum): Needs no chilling. Soak roots for 2 hours, plant in a snug pot and place straight into the warmth. Flowers in around 10 weeks

Health and safety

Equipment

• Bulbs of your choice (prepared or unprepared)
• Peat-free, multi-purpose compost
• Pots (15-20cm diameter) with drainage holes
• Saucers or trays
• Gloves
• Watering can
• Plant labels and pencils
• Support sticks or canes (for tall varieties like amaryllis or paperwhites)

1. Select your bulbs and check whether they are pre-cooled or need chilling
2. Check on the packaging how deeply the bulbs should be planted and add compost to the pot, up to the level where the base of the bulbs will sit
3. Place bulbs with the pointed shoots facing upward and the flatter base facing down. In pots, you can place them close together for a fully display - just ensure they do not touch each other or the sides of the pot
4. Cover the bulbs with more compost, leaving the growing tips exposed above the soil surface
5. Label your pots with the type of bulb and the date planted. For taller varieties, also insert support sticks around the edge, taking care not to pierce the bulbs
6. Place the pots on a saucer or tray and water until the compost is moist, ensuring all acess water drains away to avoid rotting the bulbs
7. If your bulbs require chilling, place the pots in a dark, cold (1.5°C-9°C), frost-free spot for the required number of weeks. Check occassionally and water lightly if the soil feels completely dry
8. Once shoots have grown 2-3cm tall and the chilling period is complete, move the pots to a warm, bright windowsill to trigger flowering

• Avoid overwatering. Bulbs store their own energy and moisture, and waterlogged soil causes them to rot quickly
• For festive classroom displays, start unprepared bulbs in September/October, or buy pre-cooled bulbs in November
• Once flowers fade, keep bulbs somewhere frost-free until the leaves die back naturally, then plant them into the school grounds for flowers in future years