What Are These "Bulb" Structures On My Flowers?

The summer blooming “bulb” is a term used for plants that develop from structures that are not true bulbs but rather tubers, corms, rhizomes or tuberous roots. The difference is that true bulbs planted in the fall actually require cold temperatures to develop properly. Summer planted “bulbs” are tender and cannot over-winter in the ground where harsh winters are a norm.

General Tips for Lifting Tender “Bulbs”

1. The “bulbs” should be dug after the foliage dries up or is killed back by frost, but before the ground freezes.
2. Use a garden fork or shovel, taking care not to damage the underground structure. Scrapes or nicks can lead to rot over the winter.
3. Remove soil without washing
4. Some tender “bulbs” require curing before storing away
5. Store away in peat, vermiculite or sawdust and should be kept dry and out of light during dormancy
6. If “bulbs” are looking like they are shriveling, slightly moisten storage material by misting but not soaking
7. Periodically check over the winter and remove any sections that are rotting
8. Store in an area that stays around 50°F

Guidelines for Specific Types of Tender "Bulbs"

Tuberous Begonias

• Lifting a disk-shaped tuber
• Dry tubers in a warm, dry location for 2 weeks
• Store dried tubers in sphagnum moss or vermiculite

Caladium

• Lifting a tuber and any new tubers growing from the sides of the main one
• Dry tubers in a warm, dry location for 2 weeks
• Store dried tubers in sphagnum moss, dry sand or vermiculite

Gladiolus

• Lifting a corm
• Dig up after foliage has begun to yellow
• Dry for about one week in the sun, and allow to cure at 80-85°F for 2 more weeks
• Remove the old corm and store in a cool, dry area

Calla Lily

• Lifting a rhizome
• Dig up after foliage has died back
• Store rhizomes in dry sand or vermiculite

Canna

• Lifting a rhizome
• Dig up after foliage has died back
• Store rhizomes in moist sand or vermiculite

Dahlia

• Lifting tuberous roots and crown
• Dig up after frost has killed back the foliage, being careful not to damage the crown
• Store cleaned tubers in vermiculite

Agapanthus

• Lifting a rhizome
• Pot up and bring indoors

Alstromeria

• Lifting a bulb
• Pot up and bring indoors

Eucomis (aka Pineapple Lily)

• Half hardy, may survive if well mulched
• Dig up bulb and bring in as a potted plant

For more information on growing flower bulbs, see our growing guide in the Resource Center.  We also have many types of organic and open-pollinated flower seeds for sale.