Forcing Bulbs Over Water: A Project for the Whole Family

Forcing bulbs: as easy as 1, 2, 3! Source: www.homedepot.com

I already explained in a recent article how to force bulbs in a pot of growing media, but you can also force them with no soil at all, over a container of water.

A “hyacinth vase” is typically used for this purpose. It’s a transparent or ceramic hourglass-shaped container designed to hold one bulb. The constriction at the vase’s neck is designed to support the base of the bulb and hold it above the water so it won’t sit in water and rot. Hyacinth vases have been around since at least the 18^thcentury and are easy to find in garden center that sells bulbs as well as online.

However, you don’t actually need a hyacinth vase. You can use any container with a neck the right size to hold the bulb suspended above water: for example, a small jam jar might work.

A Great Project for Kids

Forcing bulbs over water is an easy project for children. Source: www.vancouversun.com

I first experienced forcing a bulb in water in kindergarten. I was absolutely fascinated to see the plant grow from roots to bloom in such a short time. And this is something you can do with your children or grandchildren. Also, a bulb is big enough that a child manipulate it and put it in the vase. From about age six on, children are even mature enough to be able to water their sprouting bulb … under the watchful eye of a parent, of course, to remind them about regularly checking the water level.

The bulb traditionally used for forcing over water is the hyacinth (Hyacinthus orientalis). Garden centers sell them from September until near Christmas. Any bulb about the size of a hyacinth bulb could also be used instead, such as a large tulip or narcissus bulb.

Smaller bulbs, like crocus, squills and muscaris, would just fall right through the throat of a hyacinth vase, but if you look, you can find “crocus vases” online that are adapted to smaller bulbs. Plus there are lots of bottles with a constricted throat of an appropriate size. You can even grow an amaryllis (Hippeastrum) bulb over water … provided you find a container with a large enough mouth. And yes, there are amaryllis vases to be found online!

The Best Bulbs for Water Culture

Prepared hyacinths are particularly easy to force. http://www.waitrosegarden.com

The best bulb for a hyacinth vase is, of course, a hyacinth, but not just any hyacinth: a prepared hyacinth. They come in all the usual hyacinth colors and are just as deliciously perfumed, but have been, as the name suggest, pretreated by gradual cooling so that they have already undergone the “cool winter” needed to encourage bloom. As a result, they don’t absolutely need a chilling period (although cool temperatures—about 50 to 54 ° F (10 to 12 ° C)—are still best). Nor do they really need to be stuck in a dark corner: you can just put them on a window ledge and let them do their thing! And a prepared hyacinths blooms quite quickly: in as little as 6 weeks, although 9 is more likely.

Paperwhite narcissus. Source: strawberrydelivery.com

The Paperwhite narcissus (Narcissus papyraceus and its close relatives, such as ‘Grand Soleil d’Or’ and Chinese Sacred Lily) are the best narcissus to use for growing indoors over water, as they don’t require a true chilling period either. They will take normal room temperatures, although night temperatures below 65 ° F (18 °C) are best, and bloom in 5 to 8 weeks.

Other spring bulbs (crocus, squills, muscaris, tulips, other narcissus, etc.) need serious cold (33 to 40° F/1 to 9 ° C) day and night over quite a long period: usually about 14 week, preferably in the dark in a refrigerator, cold room or barely heated garage. (See Forcing Bulbs Without Twisting Arms for more details.)

And finally, there is the amaryllis (Hippeastrum) that needs no cold or dark treatment at all, just a really big vase, coming into bloom in only 5 to 8 weeks. But forcing amaryllis over water is expensive: they’re not cheap bulbs and forced bulbs bloom only once. I prefer to grow amaryllis bulbs in soil so they can be treated not as throw-aways but as true, long-lived houseplants.

So Simple!

The technique is incredibly easy.

Just add water and place the bulb in the vase. Source: http://www.gardenersworld

Fill the container with fresh water up to the neck and place the bulb, pointed side up, just inside the container, where the neck narrows. The base of the bulb should barely touch the water. Then set the container a cool, dark place.

Roots start to form within days. Source: www.gardenersworld.com

Roots form quickly and reach down into the water. You can let the water level drop considerably once roots are present: they don’t have to be entirely in water, just at least dip into water. Still, take a look every three or four days, adding more water as needed, as bulbs are thirsty creatures and the container should never dry out completely.

When a healthy sprout has formed, the container is filled with roots and the minimum number of weeks has elapsed, the plant can be exposed to light and heat. Flowering then occurs quickly: often starting in barely a week.

When the bulb stops blooming, clean the container and put it away for next year, then drop the bulb into the compost. Being grown over water will have completely exhausted it and it won’t bloom again. Don’t even think of adding fertilizer to the water to “feed” the bulb for another flowering: it will be in no better shape … and your container will quickly fill with algae.

Forcing in Pebbles and More

You can use pebbles or the substrate of your choice. Source: linaloo.typepad.com

You can also easily force bulbs in pebbles or any other fairly inert substrate, such as gravel, clay hydroculture pebbles, seashells, marbles, etc. This is, in fact, still considered forcing over water, as the substrate provides only holds the plant up: it’s the water that makes it grow.

Any decorative container with no drainage hole will do, although a transparent container will make your life easier, because you’ll not be able to see the roots growing (fascinating) and also better monitor the water level. Just drop substrate into the bottom of the container to a depth of anywhere from an inch (2.5 cm) to 5 inches (13 cm) or more. Roots will grow into this layer.

Fill the bottom with substrate, then add bulbs. Source: www.younghouselove.com

Set the bulbs on the substrate. For the most beautiful flowering, fit as many bulbs into the container as it can hold and, although you’ll read otherwise elsewhere, yes, the bulbs can touch! For added solidity, fill the interstices between the bulbs with more substrate, leaving on the tip of the bulbs exposed. Now add water up to the base of the bulbs and place the container somewhere cold and dark. Soon roots will form and the forcing is underway!

All that’s left is to check every now and then, topping up with water as needed, then bring the pots into the light and warmth when the bulbs are ready (see above).

The Paperwhite narcissus is the most common bulb grown in pebbles. Here, in seashells! Source: www.dutchgrown.com

All bulbs suitable for forcing over water are also suitable for pebble forcing, but the Paperwhite narcissus is the most popular for this use.

There you go! A simple little fall project that will bring gorgeous (and often scented) bloom into your home or office during the dark days of winter and early spring. Why hesitate? Just do it!

Forcing Bulbs Without Twisting Arms

Forcing bulbs (here, Siberian squills) simply means getting them to bloom indoors before their usual season. Source: lindenhillgardens.wordpress.com

I don’t like the word “forcing.” Although, in a horticultural sense, it simply means stimulating a plant to bloom ahead of its usual season, it somehow sounds like you’re using some sort of nasty or painful process to get them to bloom. But you aren’t. And forcing is so easy to do.

You can force perennials and shrubs to bloom early indoors, but mostly forcing is used on hardy bulbs. These are the same bulbs you normally plant outdoors in the fall for bloom next spring, but instead of planting them in the ground, you pot them up and grow them indoors.

Fall is the season for forcing bulbs. You can force bulbs left over from your fall plantings or make a special trip to the garden center for a few more. Note that bulbs may be on sale in the late fall: a good excuse for trying your hand at forcing.

The How-To

Pack ’em in: the more bulbs, the better the show! Source: http://www.tesselaar.net.au

Forcing is pretty simple. Take a good-sized pot (at least 8 inches/20 cm in diameter) and fill it to ¾ of its height with your favorite potting soil (tip: potting soil will be easier to handle if you moisten it ahead of time). Place the bulbs on the mix, flat side down, pointed side up. Don’t be stingy: stuff as many bulbs in the pot as you can. And yes, in spite of what most references say, the bulbs can touch. The more bulbs you fit into the pot, the better the effect will be!

Can you mix different bulbs in the same pot? Sure… but don’t expect them to bloom all at the same time. That almost never happens!

Next, cover the bulbs with potting mix. It doesn’t matter in the slightest if the tip of the bulb pokes through, but the bulbs will be sturdier if the lower, rounded part is well covered. Finally, water well.

Forcing hyacinth bubs over water.Source: www.thriftyfun.com

You can also force bulbs over water alone if you want to, using a hyacinth vase or a decorative cachepot with no drainage hole and stones or marbles. Just make sure the base of the bulb barely touches the water below. I’ll write more about this is an upcoming blog.

Your bulbs will need a prolonged period of cold. Source: Clair Tourigny, Les 1500 trucs du jardinier paresseux

Now comes the important part: the bulbs have to undergo a prolonged period of cold temperatures in order to bloom. That’s because they come from climates where there is a long, cold winter and, without a pronounced cold period, they won’t know when to flower. So, pack your pot of bulbs into a plastic bag (so it doesn’t dry out too quickly) and place it in a refrigerator, a barely heated garage, a cold room or other location where the temperature will remain above freezing, but below 50˚ F (10˚ C).

In fairly mild climates (zones 6 to 8), there is another option. You won’t need a plastic bag this time: just place the pots of bulbs in a trench 12 to 15 inches (30-40 cm) deep, filling it with mulch and mounding up a further 6 inches (15 cm) of mulch on top. Thus, you can easily dig them up whenever you need to.

I just know I buried the pot around somewhere around here! Source: frydayfunstuff.com

This could theoretically work in cold climates too, but it’s very awkward when the mulch is frozen and the ground covered with snow. Also, in any climate, beware that voles and other rodents may discover bulbs buried in a trench. That’s why I prefer keeping mine safely indoors.

In truly warm climates (hardiness zones 9 and above) or anywhere else winter soil temperatures don’t remain below 55˚ F (13˚ C) for months at a time, you won’t be able to put potted bulbs outdoors either. You really will need a refrigerator to get your bulbs to bloom!

The Long Wait

Patience is required. Source: techflourish.com

Bulbs need a long period of cold. 14 weeks is the norm (mark it on your calendar!), although some bulbs, such as crocuses and grape hyacinths, only need 10 weeks, hyacinths are usually fine with 9 weeks and a few of the later tulips prefer more: 15 to 16 weeks.

Of course, that’s a minimum. You can prolong the cold treatment if necessary, pretty much as long as you want to (I once forgot a pot of tulips in my fridge and pulled in out in July: they bloomed beautifully!)

During this time, water as needed: the bulbs are not actually dormant, but growing in preparation for their upcoming bloom. So you may need to give them a good watering after a month or so. Do let them drain well, though.

20181105I reallifegardensolutions.com.jpg

When new sprouts appear and the pot is full of roots, you can start exposing the bulbs to light and warmer temperatures. Source: reallifegardensolutions.com

When new pale yellow shoots appear and the pot is filled with roots, your bulbs are probably ready, especially if you have patiently waited the required 14 weeks. If so, remove the bag if there is one and put the pot in a cool but sunny spot: an east-facing window, for example. Leaves and flower stems emerge very quickly and the bulbs will soon be in bloom. Give the pot a quarter turn every three or four days to keep the stems growing straight and keep on watering them as needed. Cool temperatures are not absolutely essential and if you place the bulbs in a warm room, they’ll bloom anyway, but the stems may etiolate (stretch) and will then need staking.

Muscari (grape hyacinths) in bloom on a window ledge. Source: 20181105J danfennell.com

The show will be spectacular, but fairly short: a week or two. Ideally, you’ll have potted up plenty of other bulbs so you can pull out a pot or two every week and thus ensure continuous bloom.

Afterwards, you can simply compost the bulbs if you want, but you can also try planting them in the ground once the soil has thawed. They will bloom again in coming years, although they may need a year or two to adjust. Tulips are an exception: they don’t recuperate well from forcing and it is rarely worth doing anything but composting them.

It’s not worthwhile forcing the same bulbs a second time: forcing exhausts them. Instead, use fresh bulbs every year. Grape hyacinths (Muscari) are an exception: you can force them year after year.

Which Bulbs to Force?

Tulips tend to etiolate when forced, so grow early varieties that are naturally shorter. Source: martagon.blogspot.com

You can force any spring flowering bulb, but in a given category, early-flowering varieties usually give the best results. That’s because they tend to be shorter and therefore, even if they become a bit etiolated (which is often the case when you force bulbs at room temperatures), it doesn’t show as much.

Here are some examples of bulbs that are easy to force:

Anemone blanda
Chionodoxa: any variety
Crocus: ‘Yellow Giant’, ‘Joan of Arc’, ‘Remembrance’
Iris reticulata ‘Harmony’, ‘J. S. Dijt’
Hyacinth: ‘Blue Jacket’, ‘Delft Blue’, ‘Innocence’, ‘Queen of the Pinks’
Muscari: any variety
Narcissus: ‘Carlton’, ‘February Gold’, ‘Peeping Tom’, ‘Tête à Tête’, ‘Unsurpassable’
Snowdrop: any variety
Squill: any variety
Tulip: single early, double early and triumph tulips are best, including ‘Brilliant Star’, ‘Christmas Marvel’, ‘Couleur Cardinal’, and ‘Diana’.

Special Cases

Paperwhite narcissus: the fastest bulbs to bloom. Source: www.diy.com

Paperwhite narcissus (Narcissus papyraceus, syn. N. tazetta) don’t need a cold treatment to bloom and are the fastest of all bulbs to bloom. Plant them in early November and you’ll have flowers for Christmas!

There are also “prepared hyacinths” whose bulbs were specially treated so they can bloom without a cold period, but plant them fairly early (certainly before Christmas), as the treatment “wears off.” Note that they cost more than regular hyacinths.

Forcing bulbs: so easy to do. Why not give it a try this winter?

What to Do with Forgotten Bulbs

What can you do with the fall bulbs you forgot to plant?

So, you bought a few packs of spring-flowering bulbs (tulips, daffodils, crocuses, hyacinths, etc.) last fall, intending to plant them right away. Except it’s now winter and it’s apparently too late to plant them, what with the ground is frozen or covered with snow. It looks like you missed the boat. So, can you keep bulbs over the winter and plant them in the garden next spring?

In general, that’s not a good idea. Most of these bulbs will not bloom unless they undergo a long, cold winter. But there are several other options:

Extra-Late Planting

The most logical thing to do with fall bulbs is still to plant them outdoors, even though it’s later than normal.

If the soil is not yet frozen (that will depend on your local climate), there is no problem in planting tulip bulbs, narcissus, crocus, etc. as late as December or even January.

So what if the ground is covered with snow? Just brush the snow aside and dig a hole.

If there is snow on the ground, sometimes you can just brush it away before planting and still dig.

If the ground is frozen, but only on the surface, it’s easy enough to break through the frozen crust thus formed. Then just plant as you usually would, digging a hole three times deeper than the bulb is high (for tulips, a depth of 1 foot/30 cm is preferable) in rich, well-drained soil somewhere that receives spring sun. There is even an advantage to planting a bit late: often the surface soil refreezes quickly after planting, keeping the bulbs safe from squirrels.

No-Dig Planting

With no-dig planting, just dump packaged soil over the bulbs and let Mother Nature do the rest!

If crunching through a crust of frozen soil is not your idea of easy gardening, here’s an equally effective, but faster method.

First remove the snow, if there is any, then set the bulbs on the ground. Now, here’s the neat part: you don’t really have to dig a hole at all. Just cover them with a bag or two of garden soil or potting soil. Again, strive for a depth three times the height of the bulb. The warmth of the fresh soil will thaw the ground below, allowing the bulbs to root well… and they’ll be buried deeply enough that they won’t freeze until they’ve rooted in, which is what you want.

I’ve used the “no-dig planting” method during a January thaw and had great success.

This is the ideal method for planting bulbs where there is root competition too, such as in a wooded spot, even when the soil isn’t frozen.

Too Late, the Soil is Frozen Solid

The two previous methods only succeed when the soil is not frozen or only frozen on the surface. If the ground is frozen so deeply that a shovel can’t penetrate it, then it really is too late to plant your bulbs outside this season. But there are still other possibilities.

Forcing to the Rescue

Forcing bulbs is easy: just pot up your bulbs and keep them moist and cool.

You can also force bulbs indoors for spring bloom in pots and in fact, this is the most logical solution to apply when the ground is thoroughly frozen.

Just pot them up and water well. Seal the pot inside a plastic bag (to prevent evaporation, as you’ll want the roots to remain moist at all times) and place it in a refrigerator, a heated garage or a cold room. It takes about 13 to 14 weeks (three and a half months) of cold for the bulbs to get ready to bloom (a bit less for hyacinths), then in late March or early April, set the potted bulbs on a bright windowsill… and fill your home with blooms!

Forced bulbs just starting to bloom on a windowsill.

You will find more information about forcing in the article Forcing Bulbs without Twisting Arms.

Pre-chilling

It is also possible to store the bulbs dry in a cold spot over the winter, thus giving them the cold period they require for blooming… before you plant them. This technique is called “pre-chilling” and is commonly used to make tulips, hyacinths, narcissus, crocus, etc. flower in regions where they normally wouldn’t bloom because the winter isn’t cold enough for them (spring bulbs are cold climate plants: without a cold winter, they won’t flower). If you see tulips or hyacinths blooming at Disneyworld, on the French Riviera or in Australia, their bulbs were probably pre-chilled.

Store your bulbs cool but well-aerated.

For pre-chilling, store your bulbs bare (i.e. unplanted) in the refrigerator, a barely heated garage or in a cold room over the winter. The temperature should remain between 34˚ and 40˚F (1˚ and 5˚C) at all times. They can be stored loose in an open box or container or placed in a mesh bag, a paper bag or a nylon stocking, but never inside a plastic bag (under plastic, there is too much risk of condensation and during pre-chilling the bulbs must remain dry).

Now, where spring comes around, plant the pre-chilled bulbs outdoors as soon as possible, while the soil is still cool too cold. There is then a very good chance that not only will they bloom beautifully this first spring, but that’ll they adapt and come back to flower again and again for many springs to come… that is, if you live in a cool to cold winter area. (In warm-winter climates, such bulbs will not come back and are best treated as annuals.)

So, to resume the situation: the very best way to ensure that spring-flowering bulbs bloom beautifully not only the following spring but also perennialize well still remains planting them outdoors in the autumn according to the traditional method. But at least you now know what to do if you miss that opportunity!

Laidback Gardener Tip of the Day

Forcing Bulbs for Winter Bloom

Forcing bulbs such as hyacinths, crocus, tulips, and narcissus is not rocket science: just the pot them up in the fall, barely covering the bulb with potting soil (in fact, if the tip of the bulb still shows, that’s not a problem), then water well and seal the pot in a plastic bag, putting it in a cool but frost free place, such as a fridge, a barely heated garage or a cold room. You want cold conditions, but above freezing. Check the condition of the bulbs occasionally, watering if necessary, because bulbs, unlike other plants, actually grow and use water when stored in the cold and dark! When the bulbs are ready to bloom, remove the bag, place the pot in a well lit location, water it as needed and your bulbs will be in bloom in as little as two weeks!

Forcing bulbs takes more time than people imagine, though. Even if the bulb looks “ready”, with a well-developed shoot and many roots, it needs to have been in cold conditions for the equivalent of a winter. For most bulbs, figure 14 weeks of forcing before it is time to expose them to heat. Hyacinths are the fastest bulbs to force, usually requiring only 8 or 9 weeks of cold… at least, they’re the fastest among traditional bulbs.

There is a subcategory of narcissus, the Paperwhite narcissus (Narcissus papyraceus), that comes from a Mediterranean climate where it never gets very cold. This narcissus is not hardy in many areas (USDA zones 8 to 11) and is generally sold as an indoor plant. Just pot up Paperwhite bulbs, water them and they will be in bloom in time for Christmas!

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Forcing Bulbs for Winter Bloom

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