Caring for Flower Bulbs

Bulbs

The word "Bulb" is often used incorrectly to refer to any geophyte. Bulbs are very specific nutrient storage organs that allow a certain group of flowering plants to perennialize and brave harsh conditions. Bulbs are formed at the base of the stem from layers of modified leaves that swell with stored nutrients. Roots grow from the bottom and the stem will shoot from the top. Popular bulbous plants are onions, narcissus, amayrillis, tulips, and garlic.

Corms

Corms are vertical plant stem nutrient storage organs similar in function to tubers, but their uniform shape and vertical orientation make them look more like bulbs. The difference between corms and bulbs is that a corm is made of one solid starchy section of stem instead of multiple layers of modified leaf material. A few examples of popular garden plants that produce corms are crocus, freesia, gladiolus, and banana.

Tubers

Tubers are very similar to corms. They are solid nutrient storage organs that are made up of one solid piece of starchy plant material. The main difference is that tubers, unlike corms grow horizontal to the ground. Tubers can form on either roots or stems. Dahlia and Sweet Potato both form root tubers, and the plant just grows the tuber as part of its root system. Stem tubers are a little more complicated.

Stem Tubers: Rhizomes and Stolons

Rhizomes are spreading stems that grow horizontal to the ground often called "creeping root stalks". Rhizomes are the main stem of the plant. Nutrient-storing tubers will form along the rhizome as the plant reaches further out. Ginger, asparagus, and some varieties of iris are examples of plants that have rhizome tubers.

Stolons are also spreading stems, but the they are not the main stem of the plant. They reach out and, at the node of a stolon, tubers and new plants with vertical stems form. Stolons have two primary functions, finding light and reproduction. Strawberries and grasses, like some varieties of sedge, have stolons. Many plants that use stolons also produce rhizomes.
Root Tubers.


Storing, Planting and Caring for Your Flower Bulbs, Tubers, and Corms

Store your geophytes over winter to save you lot of money. You could just leave those rare and expensive bulbs in the ground and hope they come back next year, but it would be a lot safer to dig them up and keep them out of harm's way. Tropicals like caladiums, amaryllis, tender dahlia tubers, begonias, and callas all need to be taken up in the fall.


  • First dig your bulbs or tubers our of the ground. Be very careful not to damage them--it's best to dig them up by hand. Do this just after the first frost, or just before if severe weather is expected.
  • Move your plants to an airy place to dry out a little for about a week.
  • Cut off tops (the parts of the plant that would normally be above the ground) and clean off excess soil.
  • Store in clearly-labeled mesh bags, crate or boxes. Plastic bags trap moisture that may cause rotting.
  • Keep in a cool, dry place, away from frost and heat. If possible pack in slightly moist peat.
  • Check monthly--they should never dry to the point of shriveling.

Most bulbs can be planted again as soon as the ground warms up. Our flower bulbs will come with an information sheet providing all of the important planting information. For instance, many bulbs, corms, and tubers can go in the ground towards mid-spring, but caladiums don't need to be planted until mid to late April in most hardiness zones


Once they are in the ground, geophytes are really easy to maintain. Use a well-draining, rich planting medium. For most, keep the soil moist, but not wet. Make sure you always get as much information about the plants you buy to make sure they don't have any specific, unique needs. Bulbs, tubers, and corms all work really well in containers, and some make really interesting house plants.

Quick Bulb Planting Guide

Item

Planting Time

Flowering Time

Depth to Plant (in.)

Sun/ Shade

Allium

Spring or Fall

late spring, early summer

2 X Diam. Of the bulb

full sun

Amaryllis

4-6 weeks before booms are desired

spring, unless forced

1/3 of bulb above ground

houseplant

Anemone

fall

early spring

2-3

sun or light shade

Butterfly Amaryllis

4-6 weeks before booms are desired

spring, unless forced

base of bulb blow soil line

houseplant

Calla Lilly (Zantedeschia)

late spring

early to mid summer

3

sun

Colchium

aug.-sept.

sept.-oct.

3-4

sun or light shade

Crocus, Autumn

sept.-dec.

fall

2-3

sun or light shade

Crocus, Spring

sept.-dec.

early spring

2-3

sun or light shade

Cyclamen

late summer, early fall

fall

top of corm level with soil

shade

Eranthis

early fall

early spring

2

shade

Eremurus Foxtail Lilly

sept.-dec.

June

4-6

sun

Freesia

early spring

summer

3

sun

Fritillaria Imperialis

fall

early spring

4-6

sun

Fritillaria Meleagris

fall

spring

3-4

sun

Galanthus

fall

early spring

2-3

shade

Gladiolus, Hardy

fall or early spring

spring

2-4

full sun

Hermodactylus

fall

early spring

3-4

sun

Hyacinth

fall

early spring

4-6

sun or light shade

Ipheion

fall

early spring

3-4

sun or light shade

Iris, Bulbous

aug.-sept.

early spring

2-3

sun

Leucojum Summer Snowflake

fall

April

4-6

sun or light shade

Lily

fall or spring

early spring

4-6

sun or light shade

Lily of The Valley Convallaria

fall or spring

May-June

1

light shade

Lycoris Hardy Amaryllis

mid-summer to fall

late summer, early fall

2-4

sun or light shade

Muscari

late summer, early fall

early spring

3

sun or light shade

Narcissus, Daffodils

sept.-oct.

Apr.-May

5-6

sun or light shade

Oxalis

fall

spring

2

full sun

Ranunculus

spring

early spring

1.5

full sun

Scillia Hispanica

fall

spring

2-3

light shade

Scilllia Siberica

fall

mar.-apr.

3

sun or light shade

Tulip Hybrid

fall

spring

6-8

sun

Tulip Species

fall

spring

2-3

sun

Zephyranthes

spring

mid-summer

1-2

shade

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