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By Carol Yaw
Bulb forcing (the art of inducing plants to bloom out of season), brings
a breath of spring cheer, color, fragrance and cheer to dark winter days.
Pots of bulbs about to burst into bloom, also make wonderful holiday gifts.
Miniature daffodils, tulips, hyacinths, crocuses, dwarf iris, scillas
and others can be forced indoors from December through March. After potting
up the bulbs are placed in the cold for 9-13 or so weeks, then brought
into the warmth of your greenhouse or home to bloom.
If possible hand pick bulbs from a reliable supplier. Choose exhibition
or premium, first- rate bulbs. They should be large, firm and unblemished.
High quality bulbs are recommended as the bulbs contain the immature flowers
and food required to produce flowering plants. Stay away from "Bargain,"
damaged, soft and sprouting bulbs. You'll save little and likely have
The type of container you choose is a personal preference. The only rules
of thumb are that it has one or more drainage holes and is twice as deep
as the bulbs you are planting. Bulbs will grow equally well in plastic
Plastic pots do not dry out as rapidly as clay, are easier to clean,
lighter in weight and generally cheaper. Bulb Pans and Azalea (3/4) pots
are good choices.
Clay pots are a traditional favorite for bulbs. The downside is
that they do dry out faster and more care needs to be taken so they won't
chip and break.
If you are reusing pots make sure they have been scrubbed clean and that
clay pots are soaked for several hours to saturate their pores before
The bulbs need moisture and good drainage. A good draining, commercial
potting soil is most commonly used. You can prepare your own medium by
mixing one part potting or garden soil, one part peat moss, one part perlite
If you are going to plant the bulbs outside after forcing, add 1 tesp.
of 5-10-5 dry fertilizer to every quart of soil mix -to give bulbs an
extra boost after flowering.
Mix well and moisten with enough water to obtain a damp consistency. (Later
while planting individual pots up you can add a pinch of bone meal per
Place a few pebbles, broken crockery or something similar over the
drainage holes to prevent soil from running out the bottom.
Fill the pot about half full of soil.
For the best show, don't intermix different kinds of bulbs in the
same pot as they need different chilling times and have different bloom
Use a 4-6" pot for smaller bulbs and a 6-10" pot for larger
Arrange bulbs on soil surface gently, with pointed end up, close
but not touching, so they have room for root development.
Fill the container with more soil until bulb tips show just above
Mark your calendar to help you remember when to bring the first bulbs
in to force.
The bulbs now need cold (approx. 36-45 F.) and moisture to develop strong
roots. Place them in a dark, cool spot. Possible suggestions are an insulated
cold frame, under a porch, an unheated garage, cool cellar, old refrigerator
or outdoor trench. You may need to set boxes, straw, or black garbage
bags over your pots to keep them dark. Don't let pots freeze.
Keep the bulbs moist, not letting the soil dry out totally-- watering
about once a month. To better hold in moisture you can cover pot surfaces
with peat or sand.
After 4-13 weeks of chilling,(depending on the kind of
bulb) you will see roots emerging out of the drainage holes. Yellow shoots
will also start to show from the top of the pots.
A basic rule of thumb is when you see the roots coming out of the bottom
of the pot and 2-3 inch shoots coming above the soil it's time to bring
the pots into your home or greenhouse.
Now you are ready to mimick the arrival of spring with increased temperature
For a succession of blooms during the winter bring in a few pots from
outdoors every 2 weeks.
Transition the pots to a cool location where the temperature is in
the 50's. Light and temperature make all the difference between lanky,
low flowering plants and robust plants with strong blooms. Caution:
temperatures above 60 F will cause fast growth and few flowers.
Give them low to medium, indirect light.
Water them with houseplant liquid fertilizer at one half strength.
. Keep them moist, but not soggy. Don't let them dry out.
After buds appear mist with a sprayer, as a substitute for moist,
When foliage and buds are well developed, approx. 1-2 weeks for most,
pots are ready to move to a brightly lighted, 60-65 degree F. location.
After the flowers begin to open, to prolong their blooms, move them
out of the direct sunlight and stake if needed.
Attempts at forcing the same bulbs a second time are usually unsuccessful.
However, if you choose to, you can plant them outdoors in your landscape.
Once they return to their natural bloom schedule, in several years, they
will start blooming again.
After flowering cut the flower stems back and place in a sunny window.
Water regularly until the foliage starts to yellow. A light feeding of
fish or seaweed liquid fertilizer is helpful. As foliage withers, resist
the temptation of pulling leaves off. Carefully remove the bulbs from
the potting soil and let them dry for 2-3 weeks, then store in a cool,
dry place until fall planting.
Bulbs generally flower in 3-4 weeks after they have been moved to a warmer
temperature. From time of planting to flowering you need to allow about
17-18 weeks. Remember it is easier to hold bulbs back than to speed them
to bloom faster. Thus when you know the date you want them to be in bloom,
calculate back to the best planting time.
Following are some examples. Times may vary dependent on the bulb type and
if they are well rooted before being forced.
To bloom in January-plant in September or early October
To bloom in February for Valentine's Day-plant early-mid October
To bloom later-plant in late October or early November