Bulbs, rhizomes, corms, and tubers (usually commonly grouped together as “bulbs”) make wonderful additions to the garden.

About Bulbs

Bulbs are generally categorized as hardy vs. tender:

• Hardy Bulbs: These bulbs respond to winter’s chill to produce flowers in spring or summer.
• Tender Bulbs: These bulbs generally don’t like freezing weather and are dug up and stored indoors over the winter or (if they’re hardy in your area) grown outdoors year-round.

As with other garden plants, you can push the limits of your hardiness zone by protecting your bulb beds with a thick layer of mulch. If winter hardiness is a concern, look for cultivars specifically bred to be cold tolerant. The zones below serve as a general guide, but new varieties are constantly being developed that bend the rules!

Bulb Growing Guide

Here’s a handy guide to the winter hardiness, planting season, and bloom season for some common landscape bulbs.

Bulb Name	Zone	Bulb Type	Planting	Blooming
Allium	5	Bulb	Fall	Spring/Summer
Amaryllis	9	Bulb	Fall	Spring
Anemone	4	Tuber	Fall	Spring
Belladonna Lily	7	Bulb	Spring	Late Summer
Caladium	9	Tuber	Spring	Summer
Calla	7	Rhizome	Spring	Summer
Canna	8	Rhizome	Spring	Summer
Colchicum	5	Corm	Summer	Fall
Corn Lily (Ixia)	6	Corm	Fall	Spring
Crocosmia	7	Corm	Fall	Summer
Crocus	7	Corm	Fall	Spring
Crown Imperial	3	Bulb	Fall	Spring
Cyclamen	5	Tuber	Fall	Spring/Summer
Daffodil, Narcissus	4	Bulb	Fall	Spring
Dahlia	8	Tuberous Root	Spring	Summer/Fall
Dutch Iris	5	Bulb	Fall	Early Summer
Elephant Ear	9	Corm	Spring	Summer
Freesia	9	Corm	Fall	Indoors-Spring
Gladiolus	8	Corm	Spring	Summer
Glory of the Snow	3	Bulb	Fall	Early Spring
Grape Hyacinth	4	Bulb	Fall	Summer
Harlequin Flower	9	Corm	Spring	Summer
Hyacinth	3	Bulb	Fall	Spring
Iris	4	Rhizome	Fall	Summer
Lily	4	Bulb	Fall	Summer
Magic Lily	5	Bulb	Summer	Fall
Peacock Flower	8	Corm	Fall	Spring/Summer
Ranunculus	7	Tuberous Root	Spring	Summer
Siberian Squill	3	Bulb	Fall	Spring
Snowdrop	3	Bulb	Fall	Early Spring
Snowflake	4	Bulb	Fall	Spring
Star of Bethlehem	4	Bulb	Fall	Spring
Trillium	4	Rhizome	Fall	Late Spring
Tuberous Begonia	10	Tuber	Spring	Summer/Fall
Tulip	3	Bulb	Fall	Spring
Winter Aconite	4	Tuber	Fall	Early Spring

Further Information

• Planting Bulbs (video)
• Spring Bulb Planting Depths (article)
• Hardy vs. Tender Bulbs (article)
• How to Store Tender Bulbs Over the Winter (article)
• Hardiness and Heat-Tolerance: Understanding Planting Zones (article)

Tags: , Flowers