University of Vermont Extension
Department of Plant and Soil Science
Winter News
Article
PROPER
WATERING AND OTHER DECEMBER GARDENING TIPS
Charlie Nardozzi,
Horticulturist and
Leonard Perry, UVM Extension
Horticulturist
Growing
herbs indoors, proper watering of flowering potted plants, and
watching for
houseplant pests are some of the gardening activities for this
month.
The
outdoor gardening season may be over, but indoors you can grow many
herbs. Sow
seeds of parsley, oregano, sage, chives, and dwarf basil in clay
pots. Once
they germinate, place them under grow lights and water and fertilize
(with a
half-strength solution) only when very dry. You'll be rewarded with
fresh herbs
for your winter cooking.
Decrease water and fertilizer on Christmas cactus if the buds are
developing. To prolong the colorful bracts (the showy parts on
poinsettias),
keep them where temperatures don't exceed 70 degrees (F) during the
day or drop
below 65 degrees at night. Keep potted amaryllis in a cool (60
degrees) shaded
location until buds open. Then move it wherever you like. Cyclamen
prefer cool
temperatures, so keep them back from south-facing windows that heat
up during
the day. Cyclamen also prefer even
moisture, so don’t allow to wilt and definitely don’t keep too wet
or they may
rot.
African violets make great houseplants and will flower in winter if
given supplemental light. To propagate new plants, take a leaf
cutting, dip the
cut end in a rooting hormone powder, available at many garden
centers, and
stick the cutting in a pot filled with vermiculite, perlite, or
sand. Cover the
pot with a perforated clear plastic bag and keep the soil moist. In
a few weeks you'll have
new plants.
If you brought in your geranium
plants this fall and are growing them indoors this winter, chances
are they've
become very leggy by now. The cloudy, short days of November and
December don't
provide enough light for these plants to thrive. Cut back the plants
to about
one foot tall. They will resprout and grow bushier in the longer
days of late
winter.
If
you've brought potted plants inside after a summer outdoors, chances
are you're
now seeing a shiny, sticky substance on the leaves and small black
or green
aphids on the undersides of the leaves. Sometimes a few dunks in a
sink full of
soapy water will control them, otherwise spray them with
insecticidal soap or
horticultural oil. Aphids are very prolific, so check and treat
plants at least
weekly (or according to label directions for spray products).
The warm, dry indoor air is prime
breeding ground for spider mites on your houseplants. Look very
closely at the
undersides of leaves, at the base of stems, and on new buds for fine
webbing.
Set any suspicious-looking plants in the shower to wash off the
mites, and
repeat frequently. Or, if it's a small plant, treat as you would for
aphids.
Other
garden-related activities for this month include buying gardening
gifts for
your favorite gardener for the holidays, keeping bird feeders full
every day or
two, treating your birds to high-energy suet or shelled peanuts
(woodpeckers
especially love these in wire-mesh feeders), using sand or “safe
salt” products
on icy walks to avoid damage to plants, and decorating with
locally-grown and
produced evergreen boughs, roping, and wreaths.
(Charlie Nardozzi is a nationally known horticulturist,
author, gardening consultant, and garden coach; CharlieNardozzi.com).
Return to
Perry's Perennial
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