Forcing bulbs indoors: winter blooms from hyacinths, tulips and more

Two kinds of bulbs

Before you start, check which group your bulb belongs to. It decides whether you need a cold period at all.

How long a cold spell each bulb needs

Keep chilling bulbs at 40–45°F, in the dark, with the soil just moist. Suggested cold periods:

• Snowdrop: 10–12 weeks
• Hyacinth: 12–15 weeks
• Squill: 12–16 weeks
• Crocus, daffodil, grape hyacinth, tulip: 15–17 weeks
• Dwarf iris: 16–17 weeks
• Amaryllis, paperwhite: none

Keep bulbs in the fridge away from ripening fruit, especially apples: the ethylene gas they give off can stop flowers from forming.

Planning the bloom date

Count back from the day you want flowers. Cold period plus 2–4 weeks of indoor growth means starting 14–19 weeks earlier. Roughly: pot by early September for flowers in mid-December, and by mid-October for flowers in mid-February.

For a longer show, pot several containers and bring them out of the cold one at a time, every 1–2 weeks.

Pots, soil and how many bulbs

• Use pots with drainage holes, at least twice as deep as the bulbs are tall.
• Use a well-drained potting mix with at least 2 in of mix below the bulbs.
• Set bulbs so their tips are about level with the rim, and about half a bulb's width apart.
• In a 6-in pot: 3 hyacinths, 3–5 daffodils, 5–7 tulips or 10–12 crocuses.
• No fertilizer is needed at potting; the bulb already holds the food for this year's flower.

Potting and chilling, step by step

1. Choose large, firm bulbs and label each pot with the bulb type and the date.
2. Put mix in the pot so the bulbs will sit with their tips near the rim.
3. Set the bulbs in, pointed end up. With tulips, turn the flat side toward the outside of the pot so the first big leaves face outward.
4. Fill around the bulbs with mix, leaving the tips just showing.
5. Water thoroughly and let the pot drain.
6. Move the pot somewhere dark at 40–45°F: a fridge, an unheated garage or a trench outdoors at least 1 ft deep, covered with mulch.
7. Check every couple of weeks and add a little water only if the mix is dry.
8. When the cold period is over and shoots are showing, bring the pot indoors.

Hyacinths in a water glass

Hyacinths (and some crocuses) can be forced in water with no soil, in an hourglass-shaped forcing glass.

• Fill the glass so the water only just touches the base of the bulb; a bulb sitting in water rots.
• Keep it dark and cool (about 45–50°F) for 8–12 weeks, until the roots fill the glass and the shoot is 3–4 in tall.
• Top up or change the water once or twice a week.
• Then move it to a cool, bright window; flowers usually open in 2–4 weeks.

Amaryllis and paperwhites: no cold needed

Amaryllis: use a pot about 1 in wider than the bulb and twice as tall. Leave one-third to one-half of the bulb above the mix to reduce the risk of fungal disease. Water well once, then about weekly when the surface feels dry. Flowers appear in about 6–12 weeks.

Paperwhites: set bulbs close together but not touching in a pot or bowl 3–5 in deep, on mix or on gravel with water just below the bulbs. They flower in about 4–8 weeks. Keep them cool and sunny; warmth and low light give tall, floppy stems.

From shoots to flowers, and afterwards

• First days: after the cold period, keep pots at about 50–60°F in low to medium light for 4–5 days, until the pale shoots turn green.
• Growing on: then give bright light at about 60–65°F.
• In bloom: move out of direct sun and away from heaters; cool nights make the flowers last longer.
• Afterwards: forced tulips and hyacinths rarely flower well again and are usually discarded or planted in the garden with no expectations. Daffodils can be kept: water until the leaves yellow, let them dry, store in a cool, dry place and plant outside in autumn. If you feed the plant after flowering, follow the instructions on the product label.

⚠️ Hyacinth, daffodil (narcissus), tulip and amaryllis are toxic to cats and dogs, and the bulb is the most toxic part. Keep bulbs and pots out of reach and never store bulbs where they could be mistaken for onions. If a pet chews one, contact your veterinarian straight away.

Common problems

Frequently asked questions

Bulbs you can force indoors

HyacinthDaffodilTulipAmaryllisIris