Forcing Bulbs Indoors: Paperwhites, Hyacinth and the Alcohol Trick

Forcing bulbs is the cheapest luxury in floristry. A handful of bulbs, a bowl, some gravel, and six weeks later you have something in flower in the middle of a Washington January that would cost thirty dollars a week to buy cut.

It is also the only form of flower-buying that produces a plant your household watches. That turns out to matter more than the flowers.

The two categories

Everything divides on one question: does the bulb need a cold period first?

No chilling required — paperwhite narcissus, amaryllis. These are tender Mediterranean and South American bulbs that have no winter in their programming. Pot them and they go. This is why they dominate the December market.

Chilling required — hyacinth, tulip, crocus, muscari, daffodil, scilla. These are temperate bulbs that must experience a winter before they will flower. Twelve to sixteen weeks somewhere between 35 and 45°F, then warmth. Skip it and you get leaves and nothing else.

Pre-chilled hyacinth and crocus bulbs are sold in autumn specifically to save you this step, and they are worth the small premium. Otherwise: a paper bag in the back of the fridge from October, away from fruit — ripening apples give off ethylene, which will kill the flower bud inside the bulb while leaving the bulb looking perfectly fine.

Paperwhites, and the leaning problem

Paperwhites are the easiest bulb there is. Sit them in a bowl of gravel or glass beads with water just touching the base plate — not covering the bulb, which rots it — put them somewhere bright, and they flower in three to five weeks. Ziva is the standard variety, and it is intensely, divisively fragrant. Inbal and Ariel are milder if the classic paperwhite smell is not for you.

Their one flaw is that they grow tall, thin and floppy indoors, and by the time they flower they are lying across the table.

The fix is alcohol, and it genuinely works. Research out of Cornell established that a dilute alcohol solution stunts the stem growth by roughly a third without affecting the flowers at all. The method: start the bulbs in plain water. Once the shoot is one to two inches tall, pour off the water and replace it with a 4 to 6 percent alcohol solution — which is one part 40-proof spirit (gin, vodka, whisky) to seven parts water. Use that for all subsequent watering.

Do not use beer or wine; the sugars cause problems. Do not go stronger than about 10 percent, which damages the plant. The result is a shorter, sturdier paperwhite that stands up on its own, and it is one of the few pieces of folk horticulture with an actual controlled study behind it.

Hyacinth

The most rewarding of the forced bulbs and the most fragrant thing you can have in a house in February. One bulb scents a room; three scent a floor.

Forcing glasses — the hourglass-shaped vessels that hold the bulb above a reservoir — are the traditional method and are genuinely better than soil, because you get to watch the root system develop, which is half the pleasure. Fill so the water sits a few millimetres below the base plate, not touching it. Keep it dark and cold for the chilling period, then bring it into a cool bright room.

Bring it into warmth gradually. A bulb moved straight from a cold garage to a heated living room produces a short, stunted flower spike that barely clears the leaves. A week in a cool room first gives you a proper stem.

One practical note: hyacinth bulbs cause contact dermatitis in a lot of people — an itchy rash from the crystals in the papery skin. Handle them with gloves if you are potting more than a couple.

The others, briefly

• Crocus — fast, small, cheerful, and best in a wide shallow bowl planted densely rather than in ones and twos.
• Muscari — grape hyacinth. Excellent forced, and the blue is a genuinely rare colour indoors in winter.
• Tulips — forceable but the hardest of the group. They need the full chilling period and they still tend to come out shorter and less elegant than a bought cut tulip. Buy the cut ones.
• Amaryllis — no chilling, six to ten weeks, and the biggest visual payoff of anything on this list.

The schedule for Washington

Work backwards from when you want flowers.

• For Christmas: start paperwhites around 20 November, amaryllis in mid-October.
• For January: paperwhites started in early December. This is the better play — nobody needs more decoration at Christmas, and everybody needs something living in the second week of January.
• For February and March: chilled hyacinth and crocus brought into warmth in early to mid-January.
• Stagger them. Start a small batch of paperwhites every two weeks from mid-November through January and you have continuous flowers through the entire dead season for the price of about three bought arrangements.

Afterwards

Forced paperwhites are done — they exhaust themselves and will not flower again, and in this climate they will not naturalise outdoors either. Compost them without guilt.

Forced hyacinth and crocus can be planted out in the garden after the foliage yellows, and will usually flower again in a year or two, smaller. Amaryllis bulbs are genuinely perennial and can be brought back year after year with a summer outdoors and a dry rest in autumn.

If you want the winter flowers without the six-week lead time, our Mixed Tulip and Private Green World cover the same season, and the Biweekly Fresh Subscription is the low-effort version of the staggered-batch strategy above. But the bulbs are worth doing at least once, if only for the week in January when the shoot appears.