Bulbs for forcing indoors

The Gentle Art of Forcing Bulbs

Crocus, Hyacinth, Grape-Hyacinth, and Iris

These bulbs must be chilled. They can be forced, one bulb per jar or vase, in water alone without any soil; there are special forcing jars and vases for crocus and hyacinths, but a wide container with gravel (and dense planting) will also yield lovely results.

Crocus corms need to be refrigerated for 15 weeks. After chilling, place each corm in its own water-filled crocus forcing jar or vase at around 60°; flowers will emerge in about two weeks. Choose Crocus vernus in shades of purple, lavender, yellow, or white.

Hyacinth bulbs need to be refrigerated for 12 weeks. Then place each bulb in a water-filled hyacinth forcing jar or vase at around 70°; flowers follow in two or three weeks. Try fragrant Dutch hyacinths in shades of blue, purple, pink, or white.

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Bulbous Iris require about 15 weeks to chill, then force these bulbs in a vase of water. Expect blooms two to three weeks later. We love the clear, cobalt-blue Iris reticulata ‘Harmony’ and the black and white-detailed fall on ‘Purple Gem.’

Grape-hyacinth bulbs need 8-12 weeks’ chill time; plant as you would crocus, and expect faintly fragrant blooms in blue, purple, or white two or three weeks later.

Freesia and Tazetta Narcissus (Paperwhites)

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Forcing these bulbs technically doesn’t require cold stratification, but they do need cool night temperatures and plenty of time to root before they’ll flower. They’re powerfully fragrant.

Freesia corms take about 14 weeks from planting to bloom. Plant corms in a container filled with potting soil or sand, growing them in a spot that has daytime sun and nighttime temperatures in the 40s. Look for Dutch and Tecolote hybrids in shades of purple, blue, lavender, red, pink, orange, yellow, or white

Tazetta narcissus bulbs take five to seven weeks from planting to bloom. Use any type of container that’s twice as wide as it is high. Bulbs can be completely buried in potting soil or partially sunk in horticultural sand or decorative rocks or pebbles. Whatever medium you use, water well and put the container in a cool place (40° to 50° at night is perfect) until buds show color, then bring them indoors to bloom.

Many of these narcissus fall under the generic heading of “paperwhite,” and all produce lots of flowers from each bud. Among the best for forcing are Narcissus tazetta ‘Orientalis’ (light yellow segments, deep yellow cup), ‘Paper White’ (all white), ‘Grand Soleil d’Or’ (golden yellow), and an Israeli-bred series that includes ‘Galilee’ (white), ‘Nazareth’ (also sold as ‘Yael’; pale yellow segments, deep yellow cups), and ‘Ziva’ (white).

Daffodils and Tulips

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I hope these tulips can survive these hot spring days and super curious kitties. 🌷 #iloveflowers #tulip #laleh #forcedbulbs

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Daffodil bulbs need chilling for 16 weeks; bloom follows two or three weeks later. Try the strong-growing ‘Salome’ (pale yellow segments, apricot pink cup), the diminutive ‘Tête à Tête’ (all yellow), or ‘Mount Hood’ (all white).

Tulip bulbs need chilling for 14 to 20 weeks; bloom follows about three weeks later. Choices range from low-growing species tulips to tall hybrids. Two of our favorites for forcing are red T. greigii (try ‘Orange Toronto’) and T. kaufmanniana, whose water lily-shaped flowers come in yellow or red (‘Showwinner’ is a superior red). Each holds its flowers about a foot high.

Forcing tips

Photo by germi_p / Getty Images

Daffodil bulbs in cans. Young narcissus growing.

Chilling. To cold-stratify bulbs in the refrigerator, just store them in a mesh or paper bag in the crisper section until they’re ready to be forced. Throughout much of the West (except mild-winter parts of Arizona and Southern California), you can chill bulbs after planting simply by putting the pots outdoors. In very cold regions, place them in your garage, greenhouse, or cold frame; in milder places, you can put them in a cool, bright part of the garden. Bulbs will root and sprout during chilling.

Containers. Shop for containers and special forcing jars and vases at garden centers and through mail-order catalogs. Tall glass vessels, like a hurricane-lamp chimney or the vase holding the tulips pictured above, do a good job of supporting spindly or extra tall flower stems; you can also buy wire supports that keep stalks from leaning.

Planting. Most bulbs and corms can be put into containers almost shoulder-to-shoulder–certainly not more than 1 inch apart. Plant so that most of the bulb is buried, with just the tip poking above the potting medium. The level of the soil or sand should start out an inch below the container rim. As the bulbs start to grow, they’ll push the soil or sand up and you’ll be glad you allowed for that expansion. If you grow bulbs in soil, fertilize once with half-strength liquid fertilizer as soon as you bring them indoors.

A Beginner’s Guide to Forcing Bulbs

Almost everyone recognizes the daffodil and the tulip. They are superstars of the flower bulb world: the easy-to-grow, can’t-get-any-sunnier-in-springtime flowers. But before you rush out to add them to your outdoor garden, consider this: You also can have bulbs indoors in those not-so-warm months.

Forcing bulbs inside is a super easy technique that’s simply a sleight of hand—a trickster’s way to get blooms by faking out your flowers about what season it really is. It involves very little effort and few materials. The biggest exertion? Scheduling their arrival.

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Chilling Bulbs

Here’s the deal: Bulbs that grow indoors sometimes need a reminder that they’ve been through winter—however fake it is. In fact, all bulbs except amaryllis and paperwhites need a cold snap. What makes those two different? They don’t get cold at home in their native tropics, so they don’t need winter wherever you live. For other flower bulbs, though, you’ll have to chill them a little to get them to bloom inside; just how long depends on the bulb. Generally:

  • Chill in September, bloom in January
  • Chill in October, bloom in February
  • Chill in November, bloom in March
  • Chill in December, bloom in April

Amaryllis

Chill time: None

Bloom time: 6-8 weeks

Crocus

Chill time: 8-15 weeks

Bloom time: 2-3 weeks to bloom after chilling

Daffodil

Chill time: 2-3 weeks

Bloom time: 2-3 weeks to bloom after chilling

Grape hyacinth

Chill time: 8-15 weeks

Bloom time: 2-3 weeks to bloom after chilling

Hyacinth

Chill time: 12-15 weeks

Bloom time: 2-3 weeks to bloom after chilling

Iris

Chill time: 13-15 weeks

Bloom time: 2-3 weeks to bloom after chilling

Paperwhite

Chill time: None

Bloom time: 3-5 weeks

Snowdrop

Chill time: 15 weeks

Bloom time: 2 weeks to bloom after chilling

Tulip

Chill time: 10-16 weeks

Bloom time: 2-3 weeks to bloom after chilling

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Forcing Chilled Bulbs

  • Choose a pot deep enough that you have a couple of inches below the bottoms of the bulbs for soil and roots but that is tall enough you can cover the bulbs up to the necks.
  • Fill the bottom of the container with potting soil.
  • Use enough bulbs to fill the container. You can crowd them or give them some air. Cover with potting soil just to the necks of the bulbs.
  • Chill the bulbs for the recommended time period. The crisper drawer of your refrigerator is just fine for a handful of bulbs. An unheated basement, cold space, or inside a cold frame also works as a cool spot to keep your bulbs. Keep the soil just damp—not wet.
  • Start waking up your bulbs by giving them a few weeks of warmer (but not too warm) temps and some indirect sunlight.
  • Once the bulbs shoot up and are a couple inches tall, give them more sun and a warmer spot.

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Forcing Bulbs That Aren’t Chilled

  • Soak the roots of the bulbs in a shallow pan of lukewarm water for a few hours.
  • Fill a pot with potting soil or garden pebbles; insert the bulbs but leave the top two-thirds exposed.
  • Gently tamp down the soil or pebbles around the bulbs. Water until damp, then place in a sunny, warm spot.
  • By BH&G Garden Editors

Forcing Tulip Bulbs Indoors

Tulips are a welcome, colorful sight in spring. However, it’s not necessary to wait until April or May to enjoy these spring-blooming favorites. Tulip bulbs can be forced indoors to brighten the cold, gray days of winter. If properly planned, tulips can be enjoyed indoors from January through March.

To enjoy tulips in winter, gardeners must begin the forcing process in late summer or early fall. Good quality bulbs, a well-drained potting mix, and containers with drainage holes in the bottom are needed to successfully force tulips indoors.

For best selection of bulbs, visit local garden centers in September as soon as the bulbs arrive. Select large, firm bulbs. Avoid small, soft, or blemished bulbs. Tulip bulbs can also be purchased from mail-order companies. The best tulip types for forcing include the Triumph, Single Early, Double Early, and Darwin Hybrids.

Containers for forcing can be plastic, clay, ceramic, or metal. Almost any container can be used as long as it has drainage holes in the bottom.

Begin by partially filling the container with potting soil. Then place the tulip bulbs on the soil surface. Adjust the soil level until the tops of the bulbs are slightly below the rim of the container. The number of bulbs to plant per pot depends on the size of the container. Generally, 4 to 5 bulbs are placed in a 5-inch-diameter pot, 6 to 7 bulbs in a 6-inch-diameter pot. When placing tulip bulbs in the container, position the bulb so the flat side of the bulb faces the wall of the pot. When positioned in this way, the large lower leaf of each bulb will grow outward over the edge of the container forming an attractive border around the edge of the pot. Once properly positioned, place additional potting soil around the bulbs. However, do not completely cover the bulbs. Allow the bulb tops (noses) to stick above the potting soil. For ease of watering, the level of the soil mix should be ½ to 1 inch below the rim of the container. Label each container as it is planted. Include the name of the cultivar and the planting date. After potting, water each container thoroughly.

In order to bloom, tulips and other spring-flowering bulbs must be exposed to temperatures of 40 to 45 degrees Fahrenheit for 12 to 16 weeks. Possible storage sites include the refrigerator, root cellar, or an outdoor trench. When using the refrigerator for cold storage, place the potted bulbs in a plastic bag if the refrigerator contains apples or other ripening fruit. Ripening fruit give off ethylene gas that may impair flower development. During cold storage, water the bulbs regularly and keep them in complete darkness.

Begin to remove the potted tulip bulbs from cold storage once the cold requirement has been met. At this time, yellow shoots should have begun to emerge from the bulbs. Place the tulips in a cool (50 to 60 degree Fahrenheit) location that receives low to medium light. Leave them in this area until the shoots turn green, usually in 4 or 5 days. Then move them to a brightly lit, 60 to 70 degree Fahrenheit location. Keep the plants well-watered. Turn the containers regularly to promote straight, upright growth. On average, flowering should occur 3 to 4 weeks after the bulbs have been removed from cold storage. For a succession of bloom indoors, remove pots from cold storage every 2 weeks.

Forcing bulbs indoors

Forcing bulbs indoors is one of the best things to do in December to liven those monochromatic winter months. The bleak December winds and days of incessant rain drive even the hardiest gardener inside.

Like making jam, planting indoor bulbs can feel like a chore, but you’ll be glad you made the effort. It isn’t difficult, but there are certain questions to consider.

  • What are the best bulbs to force?
  • Should you buy prepared forcing bulbs?
  • Can you plant outdoor bulbs indoors?
  • What regime of cold and dark will they require?
  • How much food and water?

Preparing bulbs

I ask myself these questions every year. This year, I’ve decided to abandon educated guesswork and find out for certain. With many bulbs, ordinary garden varieties are fine. All that the bulbs grown inside need is protection against the worst of the wet and cold. This is true for crocus bulbs, fritillaries, anemones, tulips and narcissi bulbs.

Prepared bulbs have been pre-chilled to force them to flower at Christmas or early in the New Year. This is commonly done to hyacinths. If you can get hold of ordinary garden hyacinths early enough in autumn, you can prepare them yourself. Put them in a paper bag in the bottom of the fridge for four to six weeks.

Most other bulbs for forcing indoors need 10 to 15 weeks in the cold to flower well. Ideally, keep them at a temperature between 1.5C and 10C (at a pinch, 12.5C) in a cupboard, shed or garage. This cold period makes the bulb think it is winter, stimulating a biochemical response to make it start flowering. Amaryllis are the exception and do not require a cold spell.

Once they’ve had their cool period, you can bring them in somewhere warmer, above 15C, and they will quickly sprout, then bloom. As far as they are concerned, spring has arrived.

Most bulbs also need a period in the dark, to give the root time to develop before the light pulls the flower and leaves from the bulb. Again, amaryllis is an exception, as is freesia, ‘Paperwhite Ziva’ narcissus and all Tazetta narcissi, but for most, the dark spell is as essential as the cold one. This is often what goes wrong with cheap indoor hyacinths: they have had a cold spell, so they begin to bloom when brought inside, but the flower is tightly enclosed in the bottom of the leaves. If you knock them out of their pot, you will see that the root has hardly developed, so it can’t push out the flowers and leaves properly from the bulb.

Planting

All bulbs need to be grown in a well drained but moist medium with a soil structure strong enough to anchor them. Again, that’s often a problem with cheap bought bulbs: they are planted in peat-based compost, which becomes as light as dust when it dries and can’t begin to hold the elongating stem and top-heavy flower-head of chunky bulbs such as hyacinths and amaryllis.

A loam-based soil lightened with some grit is ideal. Because it is a mineral soil, it also has a good combination of drainage and water retention.

I use the perfect, crumbly, fine soil from the molehills scattered annoyingly over the lawn. This is the only time of year that I feel triumphant when a few more emerge each morning. Most bulbs hate sitting in the wet, so for each bucket of molehill soil, I add just under half a bucket of grit. But my soil is quite heavy: use half as much grit if you have a freer-draining loam.

Lay an inch of pure grit in the bottom of each pot, then a shallow layer of the soil-and-grit mix. Place the bulb with its pointy tip just below the soil surface, and fill in around it.

If your container has no holes in the bottom, use bulb fibre. This is expensive, but contains charcoal and grit in the right proportions. The charcoal is porous and will help keep the soil damp but not too heavy, preventing rot and disease.

If you like the idea of planting bulbs in swathes in your best salad bowls, but don’t want to ruin them, there’s an easy solution. Find a plastic bowl or pot that just fits inside your bowl and plant bulbs in those. Don’t just go for one variety of bulb, but plant as many as you can find, so you will have a succession of flowers.

It is easy to find a plastic pot to fit inside most shapes of terracotta, but it can be tricky to get one to go in a large, round bowl. I’ve just bought some cheap, flimsy colanders. The holes aren’t a problem: they save you having to pierce the bottom of a solid container with a hammer and nail. I’ve lined them with newspaper, which will let the water through but keep the soil in place. I cut off the bases of the colanders, and the match of sizes isn’t exact, but I can fill the gap with a bit of moss or cover the whole surface with turf.

I cut turfs from an area of rough grass and clipped them with scissors to fit. I did this last year and the bulbs looked great.

Watering and feeding

Anemones

Anemone corms look like crinkly lumps of dried soil. When my first lot arrived in the post, I thought the supplier had sent a pile of earth and forgotten the anemones.

Varieties Anemone coronaria are the best anemones to force. Plant them inside now and they should be flowering by March. If you plant them in September, you can force flowers by mid-February. Single flowers of a single colour are the loveliest: Anemone coronaria ‘Mr Fokker’ (deep purple-blue), Anemone coronaria ‘Cristina’ (purple-crimson), Anemone coronaria ‘Sylphide’ (deep pink) and Anemone coronaria ‘The Bride’ (pure white). Mixed-colour bulb bags often include muddy, greyish tones, without the clarity and velvety texture of these named forms.

Buying The corms should feel hard, almost like a stone.

Preparation for planting To get them off to a fast start, soak them in water for a couple of hours before planting. Leave them in just long enough so that you can make a dent in the skin of the bulb with your fingernail.

Planting medium A loam-based soil lightened with some grit is ideal.

How deep to plant About 2.5cm (1in) deep, leaving the tips just exposed.

Temperature and light/dark They don’t need pre-chilling to flower, but many people think they grow more vigorously if you cover them after planting and chill them for six weeks, at about 5C. They will flower best with bright light, a cool location and consistently moist (not wet) soil.

Watering Regular watering is crucial. Don’t let the compost dry out.

Planting to flowering 10-12 weeks Keep or plant out? Leave them where they are to flower next year, or dry them off for re-planting in the autumn.

Iris

A perfect miniature iris is as intricate as any Fabergé egg, and all the better when examined close-up. Irises make ideal plants for pots and containers. I now grow them only in pots inside.

Varieties Iris reticulata, Iris histroides and Iris danfordiae are all lovely miniature irises, ideal for forcing. There is also an iris relative, Hermodactylus tuberosus, which looks magnificent growing indoors: I first saw this green-and-black-velvet wonder growing wild on an olive terrace in Corfu when I was five, and I’ve loved it ever since. It thrives in a well drained, sunny, sheltered spot in the garden, if left undisturbed, but in a pot, it will be safe from the weather and the birds.

Buying The bulbs should be firm and not sprouting.

Planting medium A loam-based soil lightened with some grit is ideal.

Pots These are small bulbs, so shallow bulb trays are ideal, but the bigger the better.

How deep to plant Just below the soil surface.

Temperature and light/dark These irises need a spell in the cold to flower well, with a temperature below 10C for 10 to 15 weeks. They require 15 weeks in the dark.

Watering Keep compost moist.

Planting to flowering 17 weeks.

Keep or plant out? Leave them in their pots undisturbed – against a wall, perhaps – or plant them somewhere in the garden where you’ll see them clearly next year. They are nice right beside a path.

Lily of the valley

These aren’t, strictly speaking, bulbs, but you can treat them in a similar way. There are few lovelier smells, and they grow well inside. Don’t keep them in pots from one year to the next.

Buying It doesn’t matter if they have begun to sprout.

Preparation for planting Soak in warm water for a couple of hours.

Planting medium A loam-based soil is ideal.

Pot These are small bulbs, but they have an extensive root structure. Tall, narrow pots are perfect.

How deep to plant Just below the surface of the soil.

Temperature and light/dark They are often pre-cooled when you buy them, so there is no need for a cold period.

Watering Convallaria – Lily of the valley likes more moisture than most bulbs, so keep well watered. They don’t like bright light.

Planting to flowering Three to four weeks.

Keep or plant out? Plant them in the garden in a shady, moist spot and they will thrive. Do not cut off the foliage before planting. They may take a year to recover from the forcing process, but once they have settled in, they will last for decades.

Narcissi

If you’re forcing narcissi inside, go for powerfully scented forms with delicate flowers and leaves. These look and smell fantastic growing inside.

Varieties The classic ones to force are paperwhites such as narcissi ‘Ziva’and narcissi ‘Tête-à- tête’. One of my favourites is narcissi ‘Avalanche’, but almost any of the highly scented Tazetta varieties do well. ‘Ziva’ and ‘Avalanche’ are good for early flowers, while narcissi ‘Silver Chimes’ and narcissi ‘Double Pheasant’s Eye’ are good for later in the spring.

Buying These large bulbs need to be firm, but the shoots can be quite long and they’ll still grow well – it’s worth planting narcissi at almost any stage up to flowering.

Planting medium As with hyacinths, a loam-based soil lightened with some grit is ideal.

Pot Large, deep pots are ideal for their vast root structure.

How deep to plant Just below the soil surface.

Temperature and light/dark Narcissi need a spell in the cold to flower well, so keep below 10C for 10 to 15 weeks. They do not require time in the dark.

Watering Keep compost moist.

Planting to flowering Paperwhites take five to six weeks, others 16 to 18 weeks.

Keep or plant out? Paperwhites are not hardy, so leave them in their pots for next year, or dry them off and re-pot them again late in the summer. Other hardy varieties can be kept or planted out.

You may also like:

  • How to grow amaryllis (indoors)
  • Tips to keep your indoor bulbs straight
  • Amaryllis flowers for the Christmas table
  • How to plant and grow iris

Forcing Bulbs In Winter – How To Force A Bulb Inside Your Home

Forcing bulbs in winter is a wonderful way to bring a little spring into the house a little early. Forcing bulbs indoors is easy to do, whether you are forcing bulbs in water or in soil. Keep reading to learn about how to force a bulb inside your home.

Choosing and Preparing Bulbs for Forcing

Almost any spring blooming bulb can be forced to bloom indoors, but some spring blooming bulbs are more popular for bulb forcing. Some popular spring bulbs to force are:

  • Daffodils
  • Amaryllis
  • Paperwhites
  • Hyacinth
  • Tulips
  • Crocus

Choose flower bulbs for forcing that are plump and firm. The larger the flower bulb is, the bigger the bloom will be.

With the exception of amaryllis, unless you have bought flower bulbs that have been specifically prepared for forcing, you will need to prepare them. Place them in a cold place (between 35 and 45 F./2 and 7 C.) for 10-12 weeks. Many people use either their refrigerator in the vegetable drawer or an unheated garage to do this. This is called prechilling. Once your flower bulbs have been prechilled, you can start forcing bulbs indoors

in either water or soil.

How to Force a Bulb to Bloom in Water

When forcing bulbs in water, first choose a container to use for forcing. You can buy specific vases called forcing vases to grow your flower bulb indoors. These are vases that have a short, narrow necks and wide mouths. They allow the flower bulb to sit with only its roots in the water.

You do not need a forcing vase to force a bulb to bloom in water. You can also use a pan or bowl filled with pebbles. Bury the bulbs halfway into the pebbles, with the points facing up. Fill the pan or bowl with water so that the lower quarter of the flower bulb is in the water. Make sure that the pan or bowl always has water.

How to Force a Bulb Inside in Pots and Soil

Flower bulbs can also be forced inside in pots filled with soil. Fill the pot with a light potting mix. Do not use soil from your garden. Plant the flower bulbs you will be forcing half to three-quarters of the way deep into the pot. The pointy tops of the bulbs should be out of the soil. Water the bulbs and keep the soil moist.

Caring for Forced Bulbs

Keep your planted bulbs in a cool (50-60 F./10-60 C.) place until it starts to form leaves. This will help it to form a more compact flower stem, which is less likely to fall over. Once leaves appear, you can move the flower bulbs to a warmer location. They prefer bright, indirect light. Make sure to keep your forced bulbs watered. The roots should always have moisture.

Once your forced bulbs have finished blooming, you can cut the spent flowers off and plant them outside. You can find directions on planting forced bulbs outside here. The only exception to this is the amaryllis, which cannot survive outdoors year round. You can, however, force an amaryllis to rebloom. Learn how to make an amaryllis rebloom here.

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