Plant Age - Starting from seed, certain plants
have to reach a minimum age before they start to produce
flowers and seeds. Plants go through a juvenile phase in
which they cannot form seed and, in some cases, bloom.
Some trees may take up to 15 or 20 years to reach
Male or Female - There is a category of plants
that are called
dioecious. These species have separate
male and a female plants. Common examples in the
landscape are hollies (Ilex), bittersweet vines (Celastrus)
Ginkgo trees. In order to form fruit on these
plants, you must have both a male and a female plant in
close proximity. Of course, the fruit will only appear
on the female plant so the mixture is usually one male
plant for three or four females.
Cold Weather - Most shrubs and trees that bloom
in the early spring set their flower buds in the fall.
These must survive the winter cold in order to bloom.
Even though a plant is rated as hardy for your climate
zone, the flower buds are generally the least hardy part
of the plant. They may sometimes be killed because of
extreme, unusually low temperatures or by the
combination of temperatures and winter winds.
Pruning - For early flowering plants that set
their buds in the fall, a major problem can be pruning
during the winter. This essentially cuts off the flower
buds for the following season. It does not hurt the
plant but decreases the bloom display.
Fertilizer - Over applications of
lead to poor bloom. Nitrogen encourages development of
foliage and this may be at the expense of flower buds.
Although rare, a deficiency in
phosphorus may lead to
Light Conditions - Each species of plants needs a
specific minimum amount of sunlight in order to set
flower buds. Obviously this varies considerably from
plant to plant but each on has its own requirement.
Insects - Certain insect pests such as
Japanese beetles feed on flower buds and may cause
reduction or elimination of blooms.
Disease - A number of fungal diseases such as
Botrytis blight will cause abortion of flower buds. The
fireblight, may also cause loss of
bloom in members of the
Rosaceae Family such as