What are ‘summer bulbs’? Summer bulbs are summer-blooming
plants that have some type of underground storage structure. These
include dahlias, gladiola and caladium. Although commonly referred
to as ‘bulbs,’ there are a variety of different underground
storage structures (corms, rhizomes, tubers). In northern Illinois,
the vast majority of the summer bulbs are not cold hardy and will
not survive the winter outside. They are often referred to as ‘tender’
bulbs. These plants need to be dug at the end of the season and
the storage structure kept indoors until the following planting
season (after the danger of frost has passed).
Although summer is still some months away, now is the time to start
thinking about these bulbs. They usually start showing up in stores
in February and you should shop early for the best selection. Also,
many of the bulbs can be started indoors, so that by the time summer
arrives, we are placing a well developed plant into the yard.
Here is a selection of summer ‘bulbs’ that are commonly
available for sale
| Common name (Scientific Name) |
Flower |
Flowering time |
Planting depth and spacing |
Culture |
| Acidanthera (Acidanthera bicolor) |
White with a maroon center; fragrant |
Late summer into early autumn |
Plant 3-4” deep; space corms about 6” apart |
Full sun; keep soil evenly moist, but not wet; protect from
wind; staking may be needed |
| Begonia, Tuberous (Begonia x tuberhybrida) |
Wide range of colors from pastels to brights |
Summer into autumn |
Plant about 1” deep, with the concave side facing up;
space tubers about 9-12” apart |
Best in partial shade; keep soil evenly moist, but not wet;
avoid wetting the foliage |
| Caladium (Caladium x hortulanum or Caladium bicolor) |
Not grown for flowers; foliage colors are a mix of red, pink,
green and white |
|
Plant about 1” deep, with the knobby side facing up;
space tubers about 8-12” apart |
Best in partial shade; keep soil evenly moist, but not wet |
| Calla Lily (Zantedeschia species and hybrids) |
Waxy, trumpet-like flowers in a wide range of colors |
Mid-late summer |
Plant about 1” deep; space tubers about 1-2’ apart |
Full sun; keep soil evenly moist; calla lilies can tolerate
wet soils |
| Canna (Canna x generalis) |
Grown for both flowers and foliage; wide range of flower colors;
some cultivars have colored foliage |
Summer into autumn |
Plant about 3-4” deep; plant rhizomes horizontally;
space about 18-24” apart |
Full sun; best growth in a rich soil with a good supply of
moisture |
| Dahlia (Dahlia hybrids) |
Wide variety of flower types; also a wide range of flower
sizes and colors |
Summer into fall |
Plant with the crown (the end with the buds) just above soil
level |
Full sun; keep soil evenly moist, but not wet |
| Elephant Ears (Colocasia esculenta) |
Grown for foliage, not flowers |
|
Plant tuber 4-6” deep, with blunt end down; space the
tubers 2-3 feet apart |
Full sun to partial shade; moist to wet soil; protect the
plant from wind which can damage the large leaves. |
| Gladiolus (Gladiolus x hortulanus) |
Wide range of flower colors |
Mid-summer |
Plant 4-6” deep; space corms about 3-6” apart |
Full sun; keep soil evenly moist, but not wet; protect from
wind; staking may be needed |
| Pineapple Lily (Eucomis species) |
Greenish flowers in spike-like clusters atop 1-2 foot stem |
Mid-late summer |
Plant 5-6” deep; space bulbs about 1’ apart |
Full sun to light shade; well drained soil |
| Ranunculus (Ranunculus asiaticus) |
Flowers with numerous petals |
Late spring into early summer |
Plant 1-2 “ deep with “claws” pointing down;
space tubers 6-8” apart |
Full sun; very well drained soil |
| Tigridia, Peacock Flower, Tiger Flower (Tigridia pavonia) |
Unique flower with three large outer petals and three small
inner petals |
Summer |
Plant 3-4” deep and 6-9” apart |
Full sun; well drained soil; may require some protection from
wind |
