Tips To Help You Force Bulbs For Blooming Indoors

Summary: Forcing bulbs to add a splash of spring color indoors during winter needs to be “planned.” This article will help you get started in the world of forcing color with bulbs.

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Hyacinth blooming in decorative potted | sanddebeautheil-DepositPhotos

Forcing bulbs needs to be a “planned event.” Late summer is the time of blue skies, russets, golds, and reds, dreamy, hazy, lazy air, and foliage still in the landscape.

How can we remember at such a time next February’s with a low temperature, drab, sunless, short days – flowerless days, too – unless we prepare ahead for a window bulb garden?

Perhaps the glory of autumn steals our forward-thinking, so make a note on your October garden calendar right now – “forcing bulbs time.”

Start planning now for a window of red tulips rising from blue-green leaves, golden daffodils drinking in the distant sunlight, and fragrant hyacinths, white, pink, and many shades of blue.

Forcing Blub Disappointment

For a number of years, I tried varied methods of bulb forcing, gained by hearsay and bits of information gleaned from seed catalogs, magazines, and other sources, only to be disappointed when the hour of promised fulfillment arrived.

A course in “Bulb Forcing for Beginners” offered at a Botanical Garden was the answer to long-sought know-how.

The next February was a resplendent month in our house, as I “forced” a pot of six pale blue hyacinths on the hall table, darker blue spikes rising from hyacinth glasses in the windows, red and yellow tulips and tall-stemmed, golden daffodils in the sunroom, ‘Paper White’ and Gold narcissus perfuming the rooms from their pastel bowls of pebbles and creating a wonderful mix of fragrance.

Select Good Bulbs

Perhaps our earlier failures were due in part to the use of inferior bulbs or those ill-suited to indoor culture. Therefore the choice of bulbs is of utmost importance.

Select prime or specially prepared bulbs for forcing from a reliable vendor; try to order direct and avoid the middleman if possible.

Hyacinths are the easiest to force indoors and the most satisfying in their display and length of blooming, but over recent years crocus in attractive decorative containers have been high on my list.

The Hyacinth is a fairly early bloomer and rewards the grower with more than one spike to the bulb. These may be started in late August or early September, as soon as available.

The large Dutch varieties produce one large spike per bulb and are adapted to pot or glass culture. They are usually on the market in late September and should bloom ten to 12 weeks after planting. 

The indoor gardener would do well to obtain the hyacinth bulbs prepared especially for forcing.

They mature earlier and produce better flowers. They can be started in pots of loose, loamy soil, in gravel pans, or hyacinth glasses-vases with constricted necks that hold the bulb above the water. 

Hyacinth glasses are made of various shades of glass, from very dark blue and amber to ice blue or clear, placed in an east window when the hyacinths bloom, these glasses of lovely flowers bring cheer to the drab, wintry days.

Tulips for Forcing

Tulips best suited for forcing are the early doubles or singles. Snatch up the longest-lasting varieties, but a succession of plantings of several varieties keeps the house ablaze with color over a long period of time.

The best of daffodils are the tall, stout-stemmed selections.

A succession of flowering bowls of “Paper White,” Gold and Narcissus Orientalis, or Chinese Sacred-Lily, may be had by planting these easiest to grow “tender” bulbs every week or so.

Those started in August or September should mature by Thanksgiving, but the December and January potting will bloom in three or four weeks, for the flower bud matures within the bulb as time elapses.

Soil culture of all hardy bulbs is essentially the same. New or well-scrubbed and soaked “pans” (shallow clay pots) are used, although plastic pots work as well.

Place a piece of broken pot over the hole, fill the pot to within an inch and a half of the top with loose, rich soil or bagged potting mix. No fertilizer is needed as the strength for this year’s blooming is already stored in the bulb.

Cold Frame or Pit

Place five to seven bulbs, all the same variety, about an inch apart on top of the soil, and press and twist them down into the loose soil until they are buried just above the shoulder or greatest diameter.

If you have a cold frame, the potting container can be partly submerged in the soil to discourage sow bugs from entering beneath, and the space between the pots filled in with a potting soil of peat moss or leaves and leaves or other coarse material spread overall. Cover the cold frame with glass.

Or the pots can be buried in a pit about 18″ inches deep after an inch of sand has been poured over the bulbs. The sand facilitates removal from the earth later, for it can be lightly brushed off the sprouted bulbs before bringing them in. Water well, whether in cold frame or trench.

Another method of promoting root development is to place the potted bulbs in cool temperatures (55° degrees Fahrenheit ) dark basement room. Here they must be kept moist but not wet, watering every two weeks or oftener if the soil dries.

Now is the period of strong root development. Until good roots have formed, there will be no flowering. About 12 weeks after planting, the pots can be brought into a cool but light room.

Coolness now is the key to success. A breezeway, attic room, or glassed unheated sleeping porch should be an ideal location for this next stage of conditioning.

Remember, your bulbs in the garden mature and flower in the spring when the weather is very cool and the nights chill.

Do not place the pots in the sunlight. Soon the tips will become green and grow taller. The buds will appear before the leaves and foliage unfurl.

Blooming In Glasses – Draw Blooms Up

Hyacinths may need special treatment here. If the flower stalk has a tendency to remain low in the plant, make a cone of cardboard or stiff paper, leaving a hole at the top. 

Place this over the plant at the soil level.

The flower then reaches for the light and stretches up nicely. When the color begins to show in the buds, the pots can be brought into the desired location for the fulfillment of your dreams.

But avoid sunlight, unless you wish to rush the opening of the flowers for a special occasion. We kept our bulbs in bloom over a period of two weeks by giving them a cool night location and misting them with a water spray during the day if the house became too dry.

Let us not forget the hyacinths in the glasses. This is our favorite method of culture of these lovely queens of the spring bulbs.

In the fall, a bulb is placed over the collar of each glass with water barely touching the base of the bulb. The vase is placed in a cool dark area (a cold closet will do) until the glass is filled with long roots and the flower bud is just appearing.

No nutrient is added to the water, but it is replenished from time to time so that it just reaches below the bulb. When the bud and roots are developed, the treatment of the glasses is the same as that for pot culture, even to the paper cone.

The beauty and fragrance of these lovely flowers are a reward, indeed, for the painstaking effort spent.

The ‘Paper White’ or other tender narcissus bulbs are a bit easier of culture. They can be started at the end of September, if available, and in succession every two weeks or so thereafter, in shallow glazed ceramic or glass bowls.

Place a layer of clean pebbles in the bottom of the container, stand as many bulbs as will fit side to side on the gravel, water just to the base of the bulbs, and fill in up to the tips with more pebbles or gravel or small stained stones.

A collection of small shells would hold the bulbs just as well.

Potted Daffodils up closePin
Close-up of potted daffodils | Sandralise-DepositPhotos

‘Paper Whites’ to Bloom

Have you ever been disappointed by having your ‘Paper Whites’ sprout tall leaves but no flowers and then just fall over from the sheer weight of greenery?

The trouble has probably been in the early treatment of the bulbs. They do not require the same low temperatures for development as the more hardy bulbs, but they must be kept cool though not dark.

Place them out of doors on the north side of the house where they can remain until the nights approach frost temperatures, or in a screened porch or breezeway.

Of course, the later plantings must be kept indoors but cool and sunless until there is a mass of roots in the gravel bed. The buds should appear when the leaves are about an inch high.

If the leaves develop rapidly, however, and the buds have not appeared, you are keeping them too warm. When buds and leaves are about three inches high, the bowls may be brought into the room for forcing.

You can almost choose the time of blooming by temperature control. Sunlight will speed the development and the demise of the flowers.

Lilies of the Valley

Although not classified as a true bulb, the lily of the valley may also be forced for indoor blooming in February or March.

Most growers have “pips” that have been held in cold storage all winter. These may be planted in standard clay pots or azalea pots, as the roots are quite long.

Often some of the lower portions of the roots will need to be trimmed a bit to fit the pot. Good loose soil or a mixture of sand and peat will do quite well for potting.

The buds or points of the pips left about an inch above the soil will soon grow and develop leaves and flower buds at the same time if kept in the dark room at a temperature of about 50° to 60° degrees Fahrenheit for about ten to 14 days.

Then they should be watered with warm water and brought into ordinary room temperature to flower.

We have been fairly successful in digging up clumps of lilies of the valley from the garden in the fall, keeping them in a cold, dark basement, and watering them as necessary until about mid-February.

When the flower buds just show, we separate the clumps and pot them in containers of gravel, place them in our fluorescent lighted “Green Thumb Room” in the basement until leaves and buds reach the same size, then bring them into the sunroom for enjoyment.

An attractive container for lilies of the valley is a small strawberry jar, with wet sand just up to the first side hole, tips emerging from each hole, and space between the pips packed tightly with dampened sphagnum moss. Early treatment of this type of planting should be the same as the above.

Replanting Outdoors

After blooming, bulbs and pips may be allowed to dry until the leaves turn yellow, then planted outdoors for a spot of color the following spring. But new bulbs should always be obtained for the next year’s forcing.

Perhaps I have used the word “cool” too often in this article, but experience has taught me that correct temperatures, the use of prime bulbs, and patience are the essential ingredients to success in this fascinating form of indoor gardening.