BulbsBulbsPlants with Underground StructuresPlants with Underground Structures

Bulbs are plants with underground structuresBulbs are plants with underground structures

Serve as storage organsServe as storage organs

Accumulate nutrient reserves for plant survival Accumulate nutrient reserves for plant survival

through dormancythrough dormancy

Supply energy for its growth & bloom during theSupply energy for its growth & bloom during the

upcoming yearupcoming year

Five types of bulbs:Five types of bulbs:

True BulbsTrue Bulbs

CormsCorms

TubersTubers

RhizomesRhizomes

Tuberous RootsTuberous Roots

True BulbsTrue Bulbs Underground stem that contains embryonic plant insideUnderground stem that contains embryonic plant inside

These are surrounded by These are surrounded by scalesscales

Modified leaves that overlap each other (protects embryo)Modified leaves that overlap each other (protects embryo)

A A basal plate basal plate at the bottom of the bulb holds the at the bottom of the bulb holds the

scales together and produces roots scales together and produces roots

Protective papery outer skin called a Protective papery outer skin called a tunictunic

Most of them produce offsets/increasesMost of them produce offsets/increases

Division- separate these Division- separate these

from the mother bulbfrom the mother bulb

Common True BulbsCommon True Bulbs

Tulip

Hyacinth

Daffodils

CormsCorms A swollen underground stem base, it’s composed A swollen underground stem base, it’s composed

of solid tissue rather than scalesof solid tissue rather than scales

Roots grow from a basal plate at the corm’s Roots grow from a basal plate at the corm’s

bottom; the growth point is at the topbottom; the growth point is at the top

Corms have a Corms have a tunic tunic Formed from the dried bases of previous season’s leavesFormed from the dried bases of previous season’s leaves

Each corm lasts for a single year Each corm lasts for a single year As it shrinks, a new corm, or cormel (small increases) forms on top As it shrinks, a new corm, or cormel (small increases) forms on top

of itof it

Division- separate healthy new corms from the old Division- separate healthy new corms from the old

cormscorms Cormels may take 2 to 3 years to reach flowering sizeCormels may take 2 to 3 years to reach flowering size

Common CormsCommon Corms

GladioluGladioluss CrocusCrocus

TubersTubers Similar to corms, they are swollen underground Similar to corms, they are swollen underground

stem bases, but lack the corms organizationstem bases, but lack the corms organization

There is no basal plate, so roots can grow from all There is no basal plate, so roots can grow from all

sidessides

A tuber has multiple growth points scattered over its surfaceA tuber has multiple growth points scattered over its surface

Each is a scale-like leaf with a growth bud (Each is a scale-like leaf with a growth bud (eyeeye))

Perennial tubers (i.e.: cyclamen, begonia) increase in size each Perennial tubers (i.e.: cyclamen, begonia) increase in size each

yearyear

Annual tubers (i.e.: potato) disintegrate as new tubers grow Annual tubers (i.e.: potato) disintegrate as new tubers grow

Division of either kind- cut it into sections, making sure each has Division of either kind- cut it into sections, making sure each has

one or more growing points.one or more growing points.

Common TubersCommon Tubers

CyclamenCyclamenPotatoPotato

RhizomesRhizomes A thickened stem growing horizontally A thickened stem growing horizontally

partially or entirely below groundpartially or entirely below ground

Its roots grow directly from the undersideIts roots grow directly from the underside

The primary growing point is at one end of the rhizomeThe primary growing point is at one end of the rhizome

Additional growing points form along the sidesAdditional growing points form along the sides

Division- cut into sections that have visible growing pointsDivision- cut into sections that have visible growing points

Common RhizomesCommon Rhizomes

Bearded IrisBearded IrisBambooBamboo

Tuberous RootsTuberous Roots A true root, thickened to store nutrientsA true root, thickened to store nutrients

Fibrous roots for the uptake of water & nutrients develop Fibrous roots for the uptake of water & nutrients develop

from its sides & tipfrom its sides & tip

Tuberous roots grow in a clusterTuberous roots grow in a cluster

Swollen portions radiate out from a central pointSwollen portions radiate out from a central point

Growth buds are at the bases of old stems rather than on Growth buds are at the bases of old stems rather than on

the roots themselvesthe roots themselves

Division- cut the root cluster apart so each division Division- cut the root cluster apart so each division

contains both roots & part of a stem base with one or contains both roots & part of a stem base with one or

more growth budsmore growth buds

Common Tuberous RootsCommon Tuberous Roots

DahliaDahlia

Day LilyDay Lily

Where do you buy bulbs?Where do you buy bulbs?Retail nurseriesRetail nurseries

(Home Depot, Green Arrow)(Home Depot, Green Arrow)

Mail order catalogsMail order catalogs

On-line resourcesOn-line resources

Buying BulbsBuying Bulbs

• Dormant bulbs will not Dormant bulbs will not

have leaves or roots.have leaves or roots.

Dormant period: the time Dormant period: the time period when plants are not period when plants are not actively growing (growth is actively growing (growth is slowed down – usually slowed down – usually during winter) during winter)

• Bulbs should be bought and Bulbs should be bought and planted during the dormant planted during the dormant period period

Selecting BulbsSelecting Bulbs

Choose plump, firm bulbs that feels heavy for their sizeChoose plump, firm bulbs that feels heavy for their size

AVOID any that are soft, squashy, or shriveledAVOID any that are soft, squashy, or shriveled

Bulbs are graded by sizeBulbs are graded by size

Larger ones usually yield more flowers, Larger ones usually yield more flowers,

and are more expensiveand are more expensive

Planting many bulbs over a large area for bigger effect Planting many bulbs over a large area for bigger effect

earlier (Massing) is more economical using midsize earlier (Massing) is more economical using midsize

bulbs- they will build up after a year or two and be the bulbs- they will build up after a year or two and be the

size of a large bulbsize of a large bulb

Planting BulbsPlanting Bulbs

They need soil with good drainage They need soil with good drainage (otherwise (otherwise

roots will drown and the bulb will rot)roots will drown and the bulb will rot)

For poor drainage soils: plant on a slope orFor poor drainage soils: plant on a slope or

in raised bedsin raised beds

Dig an individual hole for each bulbDig an individual hole for each bulb

Prepare a complete fertilizer (10-10-10)Prepare a complete fertilizer (10-10-10)

In most soils, true bulbs should be planted about 3 times as In most soils, true bulbs should be planted about 3 times as

deep as the bulb is wide. deep as the bulb is wide.

Caring for BulbsCaring for Bulbs

Water them while they are actively growingWater them while they are actively growing This period begins after planting & continues until the This period begins after planting & continues until the

foliage dies back, and flowering is finishedfoliage dies back, and flowering is finished

Water deeply enough to penetrate the root zone; roots Water deeply enough to penetrate the root zone; roots

grow beneath the bulbgrow beneath the bulb

At the beginning of growth, a At the beginning of growth, a high-nitrogen high-nitrogen

fertilizerfertilizer needs to be applied to enhance the quality needs to be applied to enhance the quality

of the current season’s flowersof the current season’s flowers

After the bloom ends it is important to leave the leaves in After the bloom ends it is important to leave the leaves in

tact with the plant until they turn yellow & can be easily tact with the plant until they turn yellow & can be easily

removedremoved This is the time when the bulb replenishes the nutrients for This is the time when the bulb replenishes the nutrients for

the next growing seasonthe next growing season

Once flowering is finished another application of a Once flowering is finished another application of a

complete fertilizer is important, 10-10-10 or “bulb food” complete fertilizer is important, 10-10-10 or “bulb food”

high in phosphorus and potassiumhigh in phosphorus and potassium These two nutrients must reach the root zone to be effective These two nutrients must reach the root zone to be effective