beginner’s corner
Pre-planting Bulb Treatment
“Bulbs need to be
‘vernalized,’ or cold
pre-treated, in cool,
moist conditions
(35-50˚F, depending
on cultivar) for a six-
to eight-week period.”
When lily bulbs are first harvested,
usually outdoors in the late summer, the
apical meristem is vegetative. These
bulbs need to be “vernalized,” or cold
pre-treated, in cool, moist conditions
(35-50˚F, depending on cultivar) for a
six- to eight-week period. Asiatic lilies
are usually given a chilling period of
six weeks and Orientals slightly longer
with eight weeks. The vernalization
treatment can be carried out artificially
under refrigeration or if season and
temperatures permit, naturally by
placing potted plants outdoors over
winter. (Note that bulbs can also be
bought pre-chilled.) The cold treat-
ment provided during vernalization
allows the bulbs to rapidly produce a
high-quality flowering shoot.
Once chilled, the bulbs can be stored
or planted out under warm growing
conditions in a moist substrate such
as sawdust, peat, or vermiculite. Once
planted, lily bulbs begin a rapid growth
phase and the central bud contained
within the bulb will produce a leafy
stem that will eventually terminate
in flowers. Unlike other bulbs such as
tulips and hyacinth, a lily’s floral initi-
ation does not occur during the cold
treatment, but during this subsequent
growth phase. Lilies begin shooting in
one to three weeks after planting out,
depending on variety and growing
conditions. Meanwhile, one of the buds
at the base will develop into daughter
bulbs, which can later be used to propa-
gate more plants.
Asiatic lilies produce some roots from
the stem base and it is these, rather
than the basal roots, that provide
nutrients for the flower stalk. So, the
bulb must be planted at a depth that
allows sufficient room for stem roots to
develop. Standard spacing of hybrid
lily bulbs in hydroponic media beds is
usually around 4x4 inches, with a plant-
ing depth of two to four inches.
The bulbs need to be watered well
and provided with sufficient warmth
to promote bud growth and stem
development. The ideal temperature
range depends on the type of lily
being produced. Asiatic lilies produce
best within a range of 66-70˚F in
the day and 52-55˚F at night, while
Oriental hybrids need warmer daytime
conditions of 69-78˚F.
Lilies need reasonably high light
levels. The use of artificial lighting
to provide “night interruption” will
increase the rate of flower produc-
tion and help prevent bud loss due
to low light. If provided with suffi-
cient warmth and light, most lilies
Left: Dwarf varieties of lilies make great potted plants. Right: Hy droponic lily plants in bud,
grown in scoria substrate.
104
grow cycle