Download All About Hostas Constance McCarthy U of IL Extension Master Gardener

All About Hostas
Constance McCarthy
U of IL Extension Master Gardener
1 March 2014
Topics to Be Covered
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Classification and taxonomy
History
Botany
Cultivation and care
Propagation
Pests
Buying tips
Resources
Classification & Taxonomy
• Shade tolerant
– Native to woodland and forest edges
• Flowering herbaceous perennial
• Require at least several weeks of winter
chilling to achieve proper dormancy
• Grow best in open woodlands and glades
Classification & Taxonomy
• Genus: Hosta
• Some hostas also have a species
– Hosta plantaginea
• In either case, a variety is also normally given
– Hosta 'Inniswood'
– Hosta plantaginea 'Aphrodite'
History
• Native to the Far East
– Mainly Japan; also China and Korea
– First cultivation in Japan
• Initially brought to the West by diplomats
• First major shipment arrived in America in
later 1800's
• Today, new native species are still being found
in Japan
Botany
• Frost-hardy perennial
• Compact root system: rounded mounds of
foliage
• Running roots: spreading patches of foliage
• Sizes range from miniature to giant
– Height determines the size classification
– Largest: up to 3-4 feet tall x 4-5 feet wide
Leaves
• Rise directly from the roots
• Juvenile vs. mature leaves
• Two distinct parts
– Petiole
– Blade
Leaf Characteristics: Color + Margins
• Colors include: light green, chartreuse, gold, bluegreen
• Color can change as season goes on
• Margin: flat, undulate (wavy), or deeply rippled
("piecrust")
Leaf Characteristics: Margins
• Solid, variegated, mediovariegated
– Variegated: lighter color at the edge of the leaf
– Mediovariegated: lighter color in the middle
Leaf Characteristics: Shape
• Base of the leaf: wedge-shaped, rounded, slightly
lobed, deeply lobed, heart-shaped
• Leaf cupping
– Flat, wavy, twisted, cupped
Leaf Characteristics: Shape
• Leaf shape
– Very narrow, elliptic, round, lanceolate, ovate
• Leaf tip
– Curved, very long, very short, blunt
'High Noon'
'Elegans'
Leaf Characteristics: Veins & Finish
• Veins
– Appearance: flat to
deeply grooved
– Number of pairs: helpful
when identifying
unknown hostas
'Niagara Falls'
Leaf Characteristics: Finish
• Shiny
• Dull or matte
• Waxy
'None Lovelier'
'Touch of Class'
Leaf Characteristics: Surface Texture
• Smooth
• Dimpled or corrugated
– Develops with maturity of the plant
– Also known as "seersuckered"
• Puckered
• Furrowed
'Inniswood'
Leaf Characteristics: Substance
• The thickness of the leaf blade
• The greater the substance, the stiffer the leaf
• Thicker leaves are better able to resist pests
and withstand drought
• Thinner leaves are more susceptible to slug
damage
Mound Shape
• Very upright or vase-shaped
'Krossa Regal'
• Tight, compact mound
'Pearl Lake'
Mound Shape
• Sprawling form
– Lower to the ground, like a groundcover
'Daybreak'
'Curly Fries'
Flowers
• Tubular, bell-shaped
– Can also be spider
shaped
• Grow in a raceme
(flower cluster)
• Racemes are on
unbranched scapes
• Scapes rise directly from
roots
– Upright or leaning;
straight or curved
– Normally green, but can
be red or purple
Flowers
• Color range: white to deep purple
– Rarely a solid color; streaked or mottled
• Bloom time: ranges from mid-June through October
'Aphrodite'
'Stiletto'
Cultivation & Care:
Soil & Site Selection
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Fertile soil
Moist but well drained, well aerated
Protection against heat of afternoon sun
Shelter against strong winds
Hostas can be grown under black walnut trees
– Tree roots emit toxic substance that prevent many
other plants from growing
Cultivation & Care: Planting
• Location
– Bright, dappled sunlight
– Direct morning sun
• Best planted in late spring or early fall
– Plant establishes without stress of midsummer
heat and drought, or damage from frost
• Site preparation
– The key to every successful garden
– Add organic matter (compost) to the soil
Cultivation & Care: Planting
• Loosen roots of unpotted hosta
– They are quite sturdy and will tolerate being teased out
• Make a mound of dirt in the middle of the planting
hole
– Set crown of plant atop the mound, with roots running
downhill
Cultivation & Care: Watering
• Watering is especially important in the first few years after
planting
• Once established, rather drought tolerant
• During active growth: 1" per week
• Optimal watering: directly to roots using a watering can,
soaker hose, or drip irrigation
Soaker hose
Cultivation & Care: Watering
• Overhead watering
– Can cause leaf rot, lead to fungal disease
– Can destroy the waxy coating on some hostas
• Early morning watering is best
• Container-grown hostas
Cultivation & Care: Mulch & Fertilizer
• Mulch keeps roots cool and prevents water
loss from soil
– Light application in spring and fall
– Organic mulches will decompose over time and
build up humus in the soil
– Don't bury the crown with mulch
• Feed with compost or leaf mold
• Stop fertilizing about 6 weeks before first frost
Location Alternatives: Containers
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Great for dwarf or miniature hostas
Pest avoidance
Grouping several pots for effect
Troughs and hypertufa
Fairy gardens
Location Alternatives: Pond Edges
• Not in the water
• Larger hostas tend to do better
Companion Plants
• Among hostas, consider contrasts in color and
variegation
• Plants
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Rhododendron
Early spring bulbs
Trilliums
Wild ginger
Daylilies
Jack-in-the-Pulpit
Mayapple
Bloodroot
– Daylily
– Brunnera
– Snakeroot
– Epimedium
– Virginia bluebell
– Hepatica
– Geranium
– Foamflower
Companion Plants: Leaf Contrast
– Bleeding hearts
– Hellebores
– Toad lilies
– Ferns
– Solomon's seal
– Sedges and grasses
Propagation
• Seed germination
– Most hosta cultivars do not come true-to-type
from seed
• Tissue culture
– Used by nurseries and plant growers to rapidly
increase in-demand varieties
– Done in a sterile environment
– Genetically identical to the parent plant
Propagation
• Sports (mutations)
– Hostas have a high mutation rate
– The sport has different foliage color(s) than the
original ("mother") plants
• Hybridization
– Flowers of two distinct hostas are crossed
– If outdoors, must be done early in the day to
prevent bee pollination
Propagation: Division
• Most common way to
propagate
• Most hostas eventually can
or need to be divided
• "Fairy ring"
– If not divided for many
years, center of clump
appears to die back
– Solution: divide the hosta,
discarding the dead center
part of the clump
Propagation: Division
• Individual shoots or divisions are separated
from a clump (with attached crown and roots)
and replanted
• Can do at almost any time of the year
– Best time: spring, just after plant has begun to
grow
– Gives plant the longest to establish new roots
before dormancy in the fall
– Hostas divided in fall should be heavily mulched to
protect against winter damage
Propagation: Division
• Dig around
perimeter of the
plant with a
shovel
• Lift entire clump
from the ground
Propagation: Division
• Use clean, sharp knife or shovel, inserted into the
clump (between shoots)
• Replant divisions and/or share with friends
Pests & Threats: Slugs
• Smooth but irregular holes along leaf edge or
between veins
• Some hostas are more slug resistant than others
Pests & Threats: Slugs
• Avoiding the problem
– Barriers: substances, copper strips/tape
– Raise containers off ground using "feet"
– Keep garden rubbish to a minimum
• Dealing with the problem
– Use a flashlight to hand-picking them at night
– Beer traps: bury a small, wide lid or jar full of beer
in the soil so the top is flush with the soil level
Pests & Threats: 4-Legged
• Deer
– Springtime: newly emerging
leaves
– Tender hosta leaves are
delectable to deer
– Barriers
• Voles
– Voraciously devour roots,
sometimes leaving crown
intact
– Traps
– Pea gravel, crushed granite
Pests & Threats
• Melt-out
– White center of the
leaf desiccates,
becomes brown, and
drops out
– Grow susceptible
cultivars in bright,
moist locations
Pests & Threats
• Leaf scorch
– Leaves or margins
turn brown, become
dry and brittle
– Hosta leaves receive
too much sunlight
– Move the plant to a
better location
Collecting Themes
• Hostas with red/purple
petioles, scapes
• Shiny hostas
• Hostas named after
people
• Hostas with foodrelated names
'Marilyn
Monroe'
'Red October'
Buying Tips: What to Look For
• Healthy leaves
– Not droopy
– No signs of physical damage
• Healthy roots
– Plump and white
– Not encircling the bottom of the pot
• Check the mature size specifications on the
plant tag
Buying Tips: The Inside Scoop
• Hosta Fest
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Two weekends late in May; at least 175 varieties
At Al's Auto Body & Arboretum, Walworth WI
www.HostaFest.com
Arboretum with over 450 different hosta varieties
• Rich's Foxwillow Pines
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Hosta sale every May and August
Over 500 varieties
All proceeds benefit Heifer International
www.RichsFoxwillowPines.com
Resources
• Northern Illinois Hosta Society
– Wonderful members-only garden tours
– Winter scientific meeting
– Sale of "sponsor plants" every spring
• American Hosta Society
– Membership includes a subscription to the
American Hosta Journal