Care of Flowering Potted Plants - Part I

[Bob Batson]

Agricultural publication G06511 - Reviewed October 1, 1993

Care of Flowering Potted Plants - Part I

Ray R. Rothenberger
Department of Horticulture, University of Missouri-Columbia
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Chrysanthemums

Potted chrysanthemums are the most popular year-round flowering gift
plant. They are available in a wide range of colors and forms.
Although chrysanthemums normally flower in November, newly developed
methods encourage flowering all seasons of the year. Potted mums last
several weeks to a month when given proper care in the home.

Care of the new plant:

1. Place the plant in a window where it gets bright light but no
direct sun.
2. Check each day to make sure that the soil is moist. Do not allow
the plant to wilt, but do not keep the pot sitting in water.
3. Keep the plant at temperatures between 60 and 65 degrees F at
night. Daytime temperatures may be 10 to 15 degrees higher.

Reblooming chrysanthemums

Chrysanthemum varieties used for flowering potted plants are not
usually suitable for Missouri gardens. However, if there is a desire
to keep the plant, it may be rebloomed with proper attention.

Florists often pot several plants together. Separate these plants
after flowering and repot them individually. Use a 5- to 6-inch pot.
Keep these plants well watered and at temperatures close to 60 degrees
F. When new shoots appear, move them to full sun and give plenty of
water.

In summer, sink the pots outside in a sunny area where they can be
given good care. Apply a complete liquid fertilizer about every two
weeks. Additional plants can be started by rooting cuttings from the
new growth.

To develop large, bushy plants, pinch out the tip of each new shoot
when it becomes about 5 inches long. Remove only the soft shoot tips.
Do not pinch the plants after August 15.

Keep the plants outdoors as long as possible in fall. When light frost
threatens, cover the plants or lift the pots and bring them indoors.
They often can be returned outdoors during periods of mild fall
weather. When cold, freezing temperatures persist, bring the plants
indoors to stay. Place them in a sunny south window. Night
temperatures around 60 degrees F are ideal. Day temperatures of 70 to
75 degrees F are best.

Chrysanthemums flower only in response to short days (long nights).
Until the color shows in the buds, plants must be kept where they will
not be exposed to any light at night from a light fixture. Even dim
light for short periods can disrupt flowering. When the buds begin to
open, light at night will no longer effect them.

Do not expect plants forced at home to be as perfect as those grown in
a greenhouse. Greenhouse conditions are difficult to provide in the
normal home.

Hardy garden mums also grow in pots. These are suitable for outdoor
planting. Set them out in a sunny, well drained location in spring
when the ground is warm. To keep these plants low and bushy, pinch out
shoots when they are about 4 to 5 inches long. Discontinue pinching
about mid-July.

Poinsettia

The red flowering poinsettia is by far the most popular flowering
potted plant for the Christmas season. White, pink and variegated
white and pink are also available. Many new, long lasting varieties of
poinsettias are now available. If properly cared for they may last a
month or more after Christmas.

Care of the new plant:

1. Poinsettias use a lot of water. Check daily. Make sure soil
remains moist, but do not allow water to remain beneath the pot in
the saucer or wrapping. Too much water will cause the roots to
rot, and the plant will deteriorate.
2. Keep the plant out of drafts. Excessively hot, dry air from
heating ducts will reduce the life of the plant. Also avoid cold
drafts. Poinsettias are semi-tropical and can not tolerate cold
temperatures or rapid temperature changes.
3. Keep the plant where temperatures remain above 60 degrees F.
Temperatures between 65 and 70 degrees F are ideal. It is not
necessary to move poinsettias into a cool room at night.
4. Place the plant in good light but not direct sun.
5. Do not allow the plant to wilt. Poinsettias are closely related to
many desert plants. Their first response to dry conditions is to
drop their leaves in order to cut down water loss.

Reblooming poinsettias

Poinsettias are perhaps the most difficult flowering potted plants to
rebloom in the home. Unless there is a special interest to try the
technique, discard the plant after flowering.

After blooming, gradually withhold water. The leaves will then yellow
and fall. Store the dried-off plant in a cool place with temperatures
50 to 60 degrees F until spring. Water only enough to keep the roots
from drying out.

In spring, place the plant in a warm room and prune the stems back to
about 6 inches. If there is more than one plant in the pot, divide and
repot them at this time.

For repotting, use a well-drained soil. House plant potting soils
available at garden shops are satisfactory. Or use one part garden
soil, one part peat moss or leaf mold and one part sand or perlite.

After repotting, place the plants in a bright, sunny south window
until frost danger is past. Sink the pot outdoors where it gets some
wind protection but where it gets sun most of the day. Light shade in
the hottest part of the summer afternoon is desirable. Lift the pot
occasionally to keep roots from growing into the surrounding soil.

As new shoots develop, cut them back to allow two nodes or pairs of
leaves to remain. Do not pinch back shoots after mid-August.

Plants may be started from cuttings, but rooting is fairly difficult
under home conditions.

Keep the plant in good growing condition by watering and feeding
regularly during the summer. Add a complete liquid fertilizer about
once every two weeks.

Watch carefully for insect or disease problems and control
immediately. Discard diseased plants.

Before the weather becomes cool in fall, bring the plant indoors and
place it at a bright, sunny south window. Night temperatures for
flower development should be between 60 and 62 degrees F. At higher
temperatures flower development will be poor. Day temperatures may be
70 to 75 degrees F.

The poinsettia is a short day (long night) plant. Make sure that it
receives no additional light at night while flowers are forming. This
critical period begins about October 1 and continues until colored
bracts and flower buds are visible. Even short periods of dim light
can prevent flowering. If the plant is kept in a lighted room, cover
it every night at dusk with a light-tight bag or cover. Remove the
cover at about 8 a.m. each morning.

If these procedures are followed carefully, the plants should flower
by midwinter.

Azaleas

The popularity of potted azaleas has increased rapidly since they have
become available throughout the year. Several types are used for
forcing, but the care of all of them in the home is similar.

Care of the new plant:

1. Although azaleas can tolerate normal room temperatures, they will
last much longer in cool conditions. Place the plant in the
coolest part of the house where temperatures remain from 60 to 65
degrees F.
2. Keep the plant in a well lighted location, but avoid full sun
while in bloom. Sun directly on the flowers will fade them and
decrease their life. After flowering is finished, the plant should
be moved to a sunny window.
3. Never allow an azalea to dry out. Water the plant by submerging
the pot in a bucket or pan of deep water. Remove it when bubbles
stop rising. Allow excess water to drain out before returning the
pot to the saucer. Never allow the plant to wilt.
4. Use a complete, soluble liquid fertilizer about once every two
weeks if you plan to keep the plant after flowering is finished.
5. Keep faded flowers removed to prevent the development of disease
problems and maintain a good appearance.

Reblooming azaleas

Reblooming azaleas in the home is not a simple matter. After flowering
has finished, remove withered flowers and keep the plant in a cool,
sunny location. Shift the plant to a larger pot if it appears to be
potbound. Azaleas need shifting only once every few years. It is
unlikely that a newly purchased plant will need immediate repotting.

A good mixture for repotting can be made from three parts acid peat
moss and one part soil. With careful fertilization and watering,
azaleas can be grown in peat moss alone.

Submerge the potted plants outdoors in May in a semi-shaded, protected
spot. Don't neglect it during the summer. It will need water and
fertilization regularly. Watch for insect pests.

If foliage becomes yellow or chlorotic, iron uptake may be limited.
This can mean root loss from too much or too little water. It can also
result from a pH that is too high (soil too alkaline), or it may
actually be a lack of iron in the soil. Apply a chelated iron or iron
sulphate to correct the situation. Ammonium sulphate fertilizer also
helps to lower the pH and maintain the acidity of the soil. Apply
about one half teaspoon each of iron sulphate and ammonium sulphate to
one quart of water. Apply this to the plants about every two to three
weeks. About every third fertilization use a complete house plant
fertilizer instead of the above combination.

Before July 1, shape the plant by removing the tips of rapidly growing
shoots. Keep the plant outdoors as long as possible in the fall.
Protect it on the first cool or light frost nights, but bring it
indoors when hard frost is likely. Place the plant in a sunny, cool
room. It needs 40- to 50-degree temperatures from November 1 to
January 1. Do not fertilize during this period and water only enough
to keep the plant from wilting.

Buds should develop and swell. In January, move to a sunny window in a
room where temperatures are near 60 degrees F at night. In a few weeks
flowering should begin. If temperatures are excessively high during
this period buds often develop poorly and new shoot growth begins.

In warmer areas of the state, some of the Kurume varieties may be
planted outdoors. None of the Indica, or Belgian, hybrids are hardy
here.

Hydrangea

The potted hydrangea is popular for Easter and Mother's Day. With good
care it should last several weeks in the home.

Care of the new plant:

1. Water is the most important factor in caring for a potted
hydrangea. The large foliage and flower clusters use large
quantities of water. Never allow the plants to dry out. Check the
soil several times a day. If you plan to be away for a day or two,
cover the plant with a transparent plastic bag so that it will not
lose water so fast. This should not be done frequently or it will
weaken the plant and increase disease problems. Do not allow the
pot to sit in a pan of water for long periods of time. If the
plant wilts severely, submerge the soil and pot in a pan of deep
water, and allow it to remain until the soil ball is thoroughly
wetted. Drain and replace.
2. Bright light will help to keep the plant in good condition. Place
it near a sunny window but not where it gets direct sun which will
fade or burn the flowers.
3. Hydrangeas like cool temperatures. Move the plant to a cool room
at night (50 to 60 degrees F).

Reblooming hydrangeas

Outdoors: In warmer areas of Missouri, the potted hydrangea can be
planted outdoors in a protected spot after flowering has finished and
the weather has warmed up. After mild winters the plant may flower,
but after severe winters it will often be killed back and will not
bloom. Never prune hydrangea in late summer or fall. At that time
flower buds are set, and pruning will remove buds that would produce
flowers next year. Mulch the tops with straw or Styrofoam covers to
protect from being killed during the winter.

Indoors: To rebloom the hydrangea indoors, cut the shoots back after
the plant has finished flowering so that two nodes or pairs of leaves
are left on each shoot. Repot in a mixture of equal parts of soil and
peat moss. If soil is very heavy, add coarse sand or perlite. Grow the
plant in full sun or a south window.

In May, move the plant outside and sink the pot where it gets full
morning sun but light shade during the afternoon. Water regularly and
fertilize with a complete liquid fertilizer about every two weeks. For
extra large flower heads, allow only about three stems to develop.
When removing extra shoots, take out those that grow toward the center
of the plant. Lift the pot occasionally to keep root growth from
moving outside the pot.

To keep shoots from becoming too long, pinch back shoots during the
summer. The last pinch should not be made any later than July.

Keep the plant outdoors as long as possible in the fall, but bring it
indoors before a hard freeze. Keep the leaves on until November 1 if
possible. Then pick off all the leaves by hand or put the plant in
total darkness until all leaves drop naturally. The leafless plant
must then be kept at temperatures from 35 to 40 degrees F for about
six weeks. Keep the plant dry during this period.

After the cooling period, bring the plant to a sunny, cool room, with
night temperatures of 55 to 60 degrees F. Water it well and fertilize
about every two weeks. It should flower in about four months.

Color: The color of hydrangea can be controlled to some extent.
Flowers are blue if grown in acid soil and pink if the soil is near
neutral. The color of white flowers can not be changed by this method.

For blue flowers, use a soil mix with liberal quantities of acid peat
added. Water the plant three times at 10 day intervals in late summer
with aluminum sulphate (seven teaspoons per quart of water). After the
cool dormant treatment, again add the aluminum sulphate solution about
four more times at 10-day intervals. When fertilizing, do not use
fertilizers that contain phosphorous.

To produce pink flowers, keep the soil more neutral (pH 6.5-7.0). If
the soil is naturally acid, water with diluted lime water made with
2/3 teaspoon of hydrated lime in a quart of water. Use a complete
fertilizer for regular fertilizations and add one teaspoon of
superphosphate to each pot. If leaves turn yellow (chlorotic) due to
this treatment, use chelated iron or iron sulphate to correct the
condition. Use 3/4 teaspoon of iron sulphate per quart of water.

Easter lily

The Easter lily is a popular holiday plant that needs little special
treatment. Well-tended plants should bloom successively for several
weeks in the home.

Care of the new plant:

1. Keep the plant moist, but be careful not to overwater. Check
moisture daily and be sure the pot never stands in water. Root
rots can be easily brought on by overwatering.
2. Place the plant in a bright location, but avoid full sun.
3. Keep the plant in a cool place and avoid drafts.
4. When a new flower opens, carefully remove the yellow anthers. This
will prevent pollen from smudging the petals.
5. Cut off flowers as soon as they have collapsed.

Reblooming Easter lilies

Outdoors: When all blossoms have faded, reduce watering so that the
plant will gradually dry off. Cut off the stem a few inches above the
soil after the top dries.

In May after danger of frost is past, plant the bulb in a protected
place outdoors at a depth of 4 to 6 inches. Often the bulb will
produce a few flowers again in late summer or early fall.

Easter lilies are not normally hardy in the Midwest but may persist in
the garden for several years if placed in a protected spot and covered
with a mulch.

Indoors: The forcing procedures seriously weaken the lily bulb. It is
not practical to repot them and bring them indoors to try forcing them
the following winter.

Potted bulbs

Spring flowering bulbs often forced into bloom in pots are tulip,
hyacinth, narcissus (daffodil), grape hyacinth and crocus. For maximum
enjoyment, these plants are best purchased in the bud or early stages
of bloom.

Care of the new plant:

1. Place the plants in a cool spot where temperatures at night are
about 60 degrees F.
2. Do not place them in a sunny location. The warm temperatures in
sunshine will speed flower development and shorten the life of the
flowers.
3. Keep the plants moist but not standing in water. Additional
fertilization will not be necessary.

Reblooming potted bulbs

Do not try to rebloom indoors bulbs that have been forced. They can,
however, be moved into the garden and will often flower the next
spring. Discard any bulbs that have been forced in water such as
hyacinths or paperwhite narcissus.

When the bulbs have finished flowering indoors, move the plant to a
sunny location. Keep them wet enough so that leaves are able to mature
and dry gradually. When the tops have died, remove the dry foliage and
soil from around the bulbs. Store them in a dry place until fall, then
plant them outdoors in the garden.
_________________________________________________________________

Use the following URL to retrieve this and other University of
Missouri Extension publications from XPLOR, Extension Publications
Library on Request:
http://etcs.ext.missouri.edu:70/0/publications/xplor
_________________________________________________________________

Issued in furtherance of Cooperative Extension Work Acts of May 8 and
June 30, 1914, in cooperation with the United States Department of
Agriculture. Ronald J. Turner, Director, Cooperative Extension
Service, University of Missouri and Lincoln University, Columbia,
Missouri 65211. University Extension does not discriminate on the
basis of race, color, national origin, sex, religion, age, disability
or status as a Vietnam-era veteran in employment or programs. If you
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and need this publication in an alternative format, write ADA Officer,
Extension and Agricultural Information, 1-98 Agriculture Building,
Columbia, MO 65211, or call (314) 882-8237. Reasonable efforts will be
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