Alli (neugotik) wrote,
Alli
neugotik

Research for today: forcing bulbs

Forcing daffodils for indoors

They have 100 'King Alfred' type daffodils at Costco right now for $4+change; this is listed as an acceptable type for indoor 'forcing'; which is how you get indoor flowers in the middle of winter; it's really cheerful. I might be starting too late but we'll see.


Q: I love daffodils and want to be able to enjoy them during every season. I've heard you can "force" bulbs to bloom. Can I do this with daffodil bulbs?

A: The answer is yes. The problem is finding them in the off-season. You may need to refrigerate planted bulbs six to eight weeks ahead of time.
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1) The bulbs must be planted, rooted, and given a cold-moist treatment for a minimum of 13 weeks with temperatures ranging from 35 to 48 oF.
2) After being rooted and cooled, they should be placed in a well lighted 60 to 63 oF area in the home. On the average, the bulbs will take about 3 to 4 weeks to flower.
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Daffodils are not difficult to force in the home. Begin the forcing process about October 1. Large bulbs will force best. Soaking the bulbs in a rooting hormone for 24 hours before planting helps develop good root growth. Use a 6- to 8-inch pot with drainage. Use a well-drained soil and fill the pot to 2 inches from the top. Add the bulbs close together and fill the pot with soil. About 5 bulbs may be planted in a 6-inch pot. The noses of the bulbs should be exposed. Water plants thoroughly. Fertilizer will not be needed.


Place the pots in a trench outdoors and cover with soil or soil and leaf mold or peat moss so the pots are covered about 6 inches. The pots may be taken indoors for forcing when they show good top growth and flower buds are clearly visible. This usually takes 10 to 12 weeks. When the pots are first taken indoors, they should be kept in a cool room where temperatures are about 50 to 55 degrees F for about two weeks. During the next two weeks, they should have temperatures about 60 degrees F. By this time flowers should begin to open and plants may be moved where desired. Keep the plants well watered. Not all varieties force well. In general, the earliest bloom for plants forced in this way is Valentine's Day. Some cultivars that force well are Abba, Avalanche, Beryl, Bridal Crown, Cantitrice, Carbineer, Carlton, Cragford, February Gold, Fortune, Geranium, King Alfred, Peeping Tom, Printal, Saint Keverne and Silver Chimes.

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Materials Required

Bulbs -- The selection of the proper cultivars for the desired period is very important (Table 1). It is strongly suggested, since some cultivars may be in short supply, that bulb orders be placed with your bulb dealer in the spring to ensure that they will be ready to begin the forcing process in the fall.

Planting Medium -- The purpose of the planting medium is to anchor the bulbs and to supply moisture. Thus, the planting medium must be well drained and yet retain sufficient moisture for growth of the bulbs. A good mixture would be 1 part loamy soil, 1 part peat, and 1 part sand. Fertilizer should not be added to the mixture. The pH should be 6 to 7.

Containers -- Use only clean pots with adequate drainage holes. Six- to 8-inch diameter pots can be used. If they have been previously used, clean and rinse the pots thoroughly. If they are new plastic pots, be sure the holes in the bottom or sides of the pot are open. When clay pots are to be used, it is advisable to soak them overnight prior to planting so they will not draw moisture from the planting medium.

Forcing Procedures

Handling of bulbs prior to planting -- It is extremely important that all flower bulbs be handled with care at all times. They are living plants and should not be dropped or subjected to extremely high or low temperatures. After purchasing, keep the bulbs in well ventilated area. If they are in paper bags, open the bag to allow maximum air movement. If possible, store them in open trays. Keep the bulbs in a room with a temperature between 45 and 50 oF. Bulbs can be stored for several weeks at these temperatures. Temperatures above 63 oF should be avoided at all times.

Planting -- Planting can take place any time from mid-September to December, depending on the desired date of flowering, and the type of storage used. As a general rule, for early flowering, plant early, and for late flowering, plant late. For flowering in late December, the planting must be done in mid-September. For February flowering, the bulbs should be planted in mid-October and for March and April, in mid-November. Remember the minimum length of the total cold treatment should be 13 weeks, and 15 weeks is preferred.

If the bulbs were held at 45 to 50 oF (pre-cooled) prior to planting, count this time in the total weeks of cold given. Thus, if the bulbs were precooled for 3 weeks they only need 10 additional cold-weeks after planting.

When planting, the pot should be loosely filled with enough medium so the nose of the bulb will be even with the top of the pot. Place 3 to 4 daffodils in a 6-inch diameter pot and more in larger pots.

Do not press the bulbs into the medium! The medium under the bulbs should be loose so rooting will take place quickly. When covering the bulbs, do not fill the entire pot. Fill only to within ¼-inch of the top so the plants can be more easily watered.

After planting, label each pot with the name of the cultivar, date of planting, and the date to be placed in the house.

Cold Treatment -- After planting, water the medium thoroughly and place pots in a refrigerator at 35 to 45 oF. The medium should be kept moist through the rooting and cooling period. After 5 to 6 weeks, the roots should emerge out of the bottom of the pots. The shoots will subsequently emerge from the bulbs. Do not place fruit or any other ethylene-producing products in the refrigerator used for flower bulb storage and rooting.

Forcing the bulbs -- After a minimum of 13 cold-weeks, the first pots may be placed in the house. Longer cold storage will result in taller flowers, while storage shorter than 13 weeks will result in smaller plants and sometimes aborted flowers. If the first planting was made on October 1, the first plants may be taken into the house just before Christmas. For a continuous supply of flowers, bring in a few pots at weekly intervals.

In the house, place the plants in an area with a temperature of approximately 63 F. For best results, place them in direct sunlight. The plants will flower in about 3 to 4 weeks. Once the flowers begin to open, take the plants out of direct sunlight. The flowers will last longer. Since the bulbs contain enough plant food, it is not necessary to fertilize them.
Table 1. Daffodil (Narcissus) cultivars for forcing.

Yellow:
Carlton
Dutch Master
February Gold
Peeping Tom
Tête a Tête
Unsurpassable
Dutch Master
Osiris
Prizewinner
Unsurpassable

Bicolor:
Barrett Browning
Flower Record
Fortunte
Jack Snipe
Juanito
Las Vegas
Accent
Barrett Browning
Fortune
Magnet
Salome
Jules Verne

White:
Cassata
Mt. Hood
Ice Follies
Printal
Cassata

Double:
Repleat
Bridal Crown

Reference for this list (each --- represents a dif. source): De Hertogh, A. A. 1996. Holland Bulb Forcer's Guide, 5th ed. International Flower Bulb Centre, Hillegom, The Netherlands.

A container of sunny daffodils, or cheery tulips, blooming on your windowsill in February, can be a treat. In order to enjoy these beautiful blooms in winter you must make plans in late fall. All hardy bulbs must be placed in a cool, dark place for a number of weeks after you pot them up. This mimics winter conditions so that when you bring the bulbs into your home, they will behave like it is spring time!

Potting Up:

* Select a container that is at least twice as deep as the height of the bulbs. Shallow, heavy containers will not topple as readily as high containers. If you are planting your bulbs in potting mix, your pot must have drainage holes.
* Fill pot with mix (at least 2" for root growth). When bulbs are placed on this layer, their tops should be even with the rim of the pot. Use several bulbs for an attractive display. Cover with potting mix and water in to settle. Do not compact soil. Label pot with date and variety.

Cooling/Rooting Period:

* Place pots in a cool (45 ºF/7 ºC), dark place for 6 to 15 weeks, depending on the variety. Soil must be kept moist and should not be allowed to freeze during this time. A refrigerator, root cellar, or cool basement is fine. Remove pots from cold storage when the appropriate time has passed. The time recommended varies greatly so root and shoot growth can be a good indication of when the bulbs are ready. When white roots are showing through drainage holes or stems are 2" high, they are ready to force.

Forcing Blooms:

* Most types of bulbs will bloom 3 to 4 weeks after you bring your bulbs into a warm bright room. Pots should be kept at 60 ºF/15 ºC with indirect sunlight for one week. Move plants to a warmer room (68 ºF/20 ºC), with direct light and cooler temperatures to help blooms last longer. After blooming, hardy bulbs can be planted into your garden where they will bloom again in a year or two.

Easiest Bulbs for Forcing:

Hyacinths: Hyacinths are often forced singly in glass forcing vases using only water. They can also be potted up in groups. Either way, give them 10 to 12 weeks in a cool, dark place before forcing.

Iris: Dwarf iris bulbs are suitable for forcing, For top growth development they need temperatures of 55-65 degrees or they may not bloom. Bring them out for display when they bloom; they should last about two weeks. Then set the pots outside (but above40 degrees since they are not acclimatized) for later planting.

Tulips: Tulips need at least 12 -15 weeks of cold to force them well. Plant them with their flat side toward the rim of the pot so that the largest leaf will arch out over it. Bring them into a light, cool room until the leaves are up 4 inches and the buds are visible. Growth can be slowed by a cool environment or sped up by a warmer one. Plant bulbs in October to bloom in January, or slow them down to bloom later. After forcing, tulips are usually thrown away, as they do not recover well. Early, shorter varieties are the easiest to force.

Daffodils: Plant in larger, deeper pots to accommodate long, heavy roots. Place in cold treatment for 12 to 16 weeks. They need very bright, direct sunlight to bloom properly. 'Enriched, 'Dutch Master', 'Ice follies', and 'Rip Van Winkle' are good cultivars to try.

Scilla and Grape Hyacinths: Cool for 12 -16 weeks. Fill pots full with bulbs almost touching.

NAME OF BULB WEEKS OF COLD WEEKS TO BLOOM
Amaryllis/Hippeastrum none 6 to 8
Chionodoxa luciliae 15 2-3
Colchicum none 2-3
Crocus chrysanthus 12 2-3
Crocus vernus 12 2
Eranthis hyemalis 15 2
Fritillaria meleagris 15 3
Galanthus nivalis 12 2
Hyacinth 10-12 2-3
Iris danfordiae 15 2-3
Iris reticulata 15 2-3
Muscari armeniacum 12-15 2-3
Muscari botryoides alba 14-15 2-3
Narcissus 15-17 2-3
Narcissus tazetta (paperwhites) none 3-5
Narcissus tazetta orientalis none 3-5
Scilla tubergeniana 12-16 2-3
Scilla siberica 15 2-3
Tulipa 12-15 2-3

Pot your bulbs right away if you have an appropriate location immediately available, such as an old (functioning) refrigerator, a root cellar or cool basement — or if outdoor temperatures are below 45°F. Vegetable or crisper drawers can be used, but don't store bulbs in the same drawer you keep ripening fruit or vegetables which give off ethylene gas which can harm the bulbs. (Also some bulbs are poisonous, so this storage method is not recommended for households with young children.)

Potting Bulbs for Cooling/Rooting Use clean pots with drainage holes (the depth will depend on the bulbs being grown). Allow for 2 inches of soil below the bulb and select a pot large enough to allow the top of the bulb to be even with the rim when placed on the soil.

Plain potting soil is fine. You can add some bone meal or special fertilizer formulated for bulbs, just a "pinch" per bulb, to the soil mixture.

Place 2 inches of soil in the pot, then place (don't push) bulbs into position. Add enough soil to fill the pot, firming the soil gently around the bulbs being careful not to bruise them. Water well in order to settle the soil around the bulbs. Bulbs can be planted very close together, even touching, and make the best show in "crowded" arrangements.

Different types of bulbs require differing periods of time to root well. For this reason it is not advisable to combine different types of bulbs in the same pot. Label each pot with the name of the variety, planting date, and the date you intend to bring it out of storage for forcing.

Bulbs will flower some 3-4 weeks after they have been brought into warmer temperatures. Thus, from time of planting to flowering, allow a period of 15 weeks, comprised of 12 weeks for rooting, 3 weeks in warmer temperatures to flower. (It is easier to hold bulbs back than to speed them up, so when you know the date you want them to be in flower, calculate accordingly the best planting time. (For Valentine's Day flowers, for example, plant bulbs in early- to mid-October).

The following timetable will help plan a forcing schedule in order to have bulbs in flower at a given date. Remember that these can vary, and in all cases, the bulbs must be well rooted before being forced.

* To flower in January, plant in September or very early October
* To flower in February, plant early- to mid-October
* To flower later, plant in late October or early November

There are exceptions: amaryllis and Paperwhite narcissus.

Other Dutch Bulbs for Forcing

Forced tulips do not do quite as well as garden planted tulips because they require a fairly long rooting period at even (non-fluctuating) temperatures to be successful. Allow at least 15 weeks.

Experiment with a few pots of different varieties. One to try is the distinctive 'Princess Irene'. This single early tulip is orange with purple flame markings. The bright yellow 'Monte Carlo' is a double early tulip, a cultivar that has twice as many petals as most tulips.

Tulip Tip: Plant bulbs with flat side facing the rim, this will position the larger outer leaves toward the pot rim, where they will drape gracefully over the edge of the pot.

Daffodils require very bright light, such as that found in a greenhouse, to flower well. Too little sun results in leggy growth and no blossoms. Only the miniature varieties (hybrid) daffodils are recommended for home forcing. Daffodils usually require a 12-14 week rooting period.

Once removed from the rooting area, daffodils must be placed in a location that receives lots of sun, say an enclosed porch or sun room or under a skylight.

Lily-of-the-Valley are often pre-cooled when you buy them, so they will bloom three to four weeks after planting. Ask your supplier.

Freesias don't require a cooling period; however they usually require a lot of sunshine and about three months of growth time before they bloom. These fragrant flowers do best in a very bright room with daytime temperatures of about 70°F and nighttime temperatures of about 50°F.



Unlike most flower bulbs which have been forced indoors and are usually of little value for outdoor plantings, forced daffodils (Narcissus) can be removed from the pot and placed outdoors in climatic zones 4 to 8. Do this in early spring. Most of them will flower 1 to 2 years later.


Ooh, and here's a neat way to present the flowers after they bloom with step by step photos:

Indoor Daffidol Project
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