University of Vermont Extension
Department of Plant and Soil Science
Dr. Leonard Perry, Extension Professor
University of Vermont
you hear the word “bulbs”, the first plants that come to mind are
spring-flowering ones such as daffodils and tulips. Yet there are
“tender” bulbs that produce
summer flowers, providing an addition to bedding plants. They
provide beauty in landscapes, are easy
to grow, and can be dug and saved for replanting year after year,
economical. Not included in this
group are the hardy perennials from bulbs, such as most lilies or
number of different types of tender summer bulbs provide a range of
interesting blooms and foliage. Among my favorites are tuberous
gladiolus, canna, and dahlia. Although
they’re commonly referred to as “bulbs”, these plants actually grow
storage organs such as tubers (swollen underground stems, as with
corms (flattened underground stems, as with crocus), or rhizomes
horizontal, underground stems as with the perennial bearded iris).
begonias come in red, pink, orange, salmon, yellow, and white and
can grow to a
diameter of 12 to 14 inches. Although they can't be planted in the
mid-May, you can get a jump on the season by planting tubers in
or pots in March or April.
indoor starting, fill containers with coarse peat moss, or soilless
Press the tubers into the medium three to four inches apart, with
side up. Place containers in a dark room at 65 to 70 degrees F. Once
start to develop, add more medium to cover the tubers. Move to a
Keep the mix moist, but avoid overwatering as tubers may rot.
two to three weeks with liquid fertilizer according to recommended
mid-May, plant in a well-drained and partially shaded area. Set
tubers in the
they are barely covered. Place 18 to 24 inches apart
to allow plenty of space for growth and air circulation. Fertilize
and water when soil is dry,
preferably in the morning or early afternoon to allow foliage time
before nightfall. This reduces the chance of disease.
the frost has killed the foliage, dig the tubers, remove the
foliage, and dry
the tubers for two or three days. Store
in peat moss or sawdust in boxes, not plastic bags. Place in a
that is dry and about 50 degrees F.
corms can be planted as early as May 1 though, by staggering the
(every two weeks until mid June), you can have flowers all summer
long. Set the
corms four to five inches deep and five to six inches apart. You can
in rows a foot or so apart, with a wider aisle every 3 rows. Use a
organic, or bulb fertilizer, mixed into the soil at planting. Keep
plants watered if soil starts to dry
foliage has dried in late fall, dig the corms, brush off the soil,
and snap off
the dead tops and old corm. Spread in a dry, cool place for three or
to dry. Pack in sawdust or dry peat moss, and store in a dry, cool
place at 35
to 40 degrees F. Check periodically throughout the winter for rot or
a tall plant with bright red flowers, can grow to a height of three
feet, depending on variety and climate. Like the begonia, it can be
indoors in pots (follow directions above), or planted directly in
the garden in
a well-drained location with full sun. The hotter the spot the
cannas love heat. Planting cannas by the south side of the house or
surfaces where they will get plenty of heat is ideal. One limitation
in cool climates, and getting them to bloom, is cold summer nights.
rhizomes a few inches below the surface and 18 to 24 inches apart.
Water thoroughly after planting, and fertilize
beginning when shoots first appear.
foliage has been killed by frost in fall, remove the dead tops and
dig up the
rhizomes. Shake off excess soil, and let dry for a day. Store in dry
or sawdust in boxes (not plastic, as these keep bulbs too wet),
burlap sacks in a dry, 45 to 50 degree F location. Do not allow to
freeze. If plants are in pots, merely cut the frosted
foliage off and place pots in a non-freezing but cool location. You
don't need to water until next spring.
can get several diseases, the most important being one of several
viruses. These have spread widely in recent years
through the sale of infected plants. If
your plants have unusual streaking, distortion, or brown areas, they
virus-infected, and should be discarded in the trash not the
compost. When buying new plants, choose ones listed as
virus-free from reputable firms.
are very popular, coming in most colors, many flower styles and
sizes, and on
plants from one foot to 6 or more feet high.
Treat similar to cannas, only stake plants that will get over two
high (usually with a single stake), and keep the winter storage
material for tubers
slightly moist (but not wet). Dahlias
grow better than cannas in cool climates.
you want less common summer-flowering tender bulbs, consider the
montbretia (Crocosmia) with its tall flower spikes
in red, orange or yellow in mid-summer; white spider lily (Hymenocallis);
Guernsey lily (Nerine),
often in reds and pinks; or the white fragrant spikes of tuberose (Polianthes).
Caladiums are a foot or two high, grown for
their colorful leaves, not flowers. From
their tubers arise elephant ear-shaped leaves in all many bright
combinations, particularly red, pink, white, or green. These
tropical plants are a good choice for
shade and warm sites, as are the related and larger elephant ears (Colocasia,