University of Vermont Extension
Department of Plant and Soil Science
FALL CARE FOR SUMMER BULBS
Dr. Leonard Perry, Extension
University of Vermont
Cannas. Gladioli. These are the most common summer-flowering
perennials that grow from bulbs or other storage organs, and that
over winter in northern climates. Yet it's easy to overwinter
other cold-sensitive perennials that grow from bulbs, corms, and
indoors so you can replant next spring.
food storage organs (actually underground stems) are often just
referred to as bulbs, although technically this refers to those
pointed ones with scales such as daffodils.
Corms are the flattened ones, as with gladiolus. Tubers are the
large, irregular swollen storage
organs such as with dahlias or tuberous begonias.
cannas and tuberous begonias that you've grown in containers, the
easy. These can be stored indoors over winter in their pots. Just
check for insects or plant diseases before bringing them into the
Once the foliage dies back with cold and frosts, trim the plants
back to just
above the soil line. Place in a cool but non-freezing (a cool
garage, 40 to 55 degrees is ideal), dry place with good air
circulation. Most basements, particularly if heated, are
too warm. Just leave pots there until
early spring, but mark your calendar so you don’t forget about them,
as I did
plants in the garden, start by cutting back the foliage to a few
ground after it is frosted and turns black. Then, with a spade or
tool, carefully loosen the soil around each plant about six to eight
from the crown of the plant. Dig deep enough to get below the
plant, taking care not to cut or
otherwise cause a wound as this may expose the plant to infection.
accidentally cut the plant's tubers, allow it to dry out so a scab
before putting it in winter storage.
Store cool and dry, such as in dry peat moss, sand, sawdust, or
Some prepare tuberous begonias for wintering
and dormancy by reducing watering and stopping fertilizer in late
early fall. Removing any flowers in
early fall helps the plant put energy into the roots, not more
when leaves turn yellow or are frosted, cut the stems about 4 to 5
the tuber. Allow plants to dry indoors
for a few days until the stems are loose and easily pull off.
Remove roots and some soil, but don’t wash
Gladiolus, crocosmia (hardy to zone 5, colder
with reliable snow cover), summer hyacinth (Galtonia),
cluster lilies (Brodiaea), flame
freesia (Tritonia), wand flower (Sparaxis), and
acidanthera are handled
similarly, only they can be left in the garden later into the fall,
late October or early November for gladiolus, but before freezing
freesia. Dig plants, cut the mostly
browned tops off just above the corm or bulb, and remove some roots
and soil. For gladiolus, remove and discard the old,
shriveled corm. Store the wand flower and cluster lilies warm (65 to
degrees), the others cooler. Use a dry material, as used with
corms, tubers, or bulbs in a paper or mesh bag (as you sometimes get
or potatoes at the store). Do not use plastic bags. Moisture will
build up inside the bag, causing rot. Then store cool and dry,
sure to keep from freezing. If you have
more than one type of summer bulb, make sure to label bags (or pots
if left in
these) if you want to keep track of each separately.
Dahlias, foxtail lily (Eremurus), and crimson flag (Schizostylis)
are stored slightly different, as they must be kept very slightly
moist or they
will shrivel and dry out. But keep them
from being too damp, or they will rot.
They are dug as other bulbs, right when the frost blackens the
Cut the stems off, remove soil from the tubers, and allow to dry or
“cure” in a warm, dry place for a day.
Don’t leave longer, or they will shrivel.
store tubers or bulbs in very slightly damp peat moss, sawdust,
similar, making sure it is not wet. You
can use pots, burlap, onion bags, or similar storage material that
air. As with corms, they’ll rot in
plastic bags, unless bags are perforated with many holes (but then
material often leaks out). Once cured, I
like to pot them into fairly dry potting soil so they are ready to
indoors next spring. Then store cool,
dry, and non-freezing.
less common bulbs, treated similar to dahlias, are the poppy
lily (Sprekelia), Mexican shellflower
(Tigridia), calla lilies (Zantedeschia), gloriosa
lily (Amaryllis), and Zephyr lily (Zephyranthes).
Keep all but the first three warmer (50 to 60
degrees). These all can be stored in dry
sand, peat moss, or vermiculite.
in gardens for a tropical effect, and often just grown as annuals,
elephant ears (Colocasia, Alocasia)
and caladiums. If you have these in pots, or in the garden and
pots for winter indoors, remove all but the top couple of leaves.
Keep on the dry side over winter as they are
semi-dormant, and in bright and cool (45 to 60 degrees).
If you want to store elephant ear corms or caladium
tubers, dig as you would dahlias when tops are just frosted, or
mostly died. Cure for a day, then store
cool and in a dry substance. A few elephant
ear cultivars (cultivated varieties) such as ‘Black Magic’ don’t
so should be kept over winter growing in pots.
are several less common, often tropical, summer-flowering plants
that you may grow outdoors in pots in northern climates, and that
brought indoors before frost. Allow
plants of achimenes to dry out, and store the “rhizome” roots dry
and cool (55
to 65 degrees). Store Nerine lily bulbs
either bare or in pots, dry and cold but not freezing. Keep plants
slightly moist for pineapple lily (Eucomis), blue African
lily (Agapanthus) and Peruvian lily (Alstroemeria),
which can be stored cold
but not freezing. Store crinum lily
bulbs similarly, or keep in containers in a bright and cool site.
Keep pots of spider lily (Hymenocallis) bright and cool, or
store their bulbs dry at these
temperatures. Bring tuberose pots
indoors, and keep cool and bright until blooming; then allow plants
to dry and
go dormant. Veltheimia, a relative of
the hyacinth, can be grown in pots in bright and cool conditions,
blooming in winter.