University of Illinois Extension

 


Sharon Yiesla, Unit Educator, Horticulture, Lake County

Past Issues

Want to know when a new issue comes out? Sign up for eNews

Think Summer, Buy Summer Bulbs Now

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

 

 

February - March 2005: Repair Storm Damaged Trees with Care | Diseases and Insects of Shrubs and Small Trees | Think Summer, Buy Summer Bulbs Now | Winter Damage to Home Lawns

 

Past Issues

Want to know when a new issue comes out? Sign up for eNews