Vegetable Garden
Rich Marini
Department of Horticulture
Penn State University
Unit 1: Garden Planning
(Let’s Plan)
• Preparing for a Vegetable Garden
• Making the most of the Garden Space
Preparing for a Garden
• Develop plans in February
• Select a site – avoid shade, poor soil, wet
and low areas, and walnut trees
• List the vegetable species & varieties –
consider season
• Decide how much to grow – how will
produce be used
• Make a planting map
Planting Map (24’ x 50’)
pumpkins
melons
6’
2’
2’
spinach (3/20) lettuce(3/20) radishes (3/20)
Onions (4/1)
gr. beans (4/15)
gr. beans (5/8)
3’
carrots (4/15)
peppers (5/15)
4’
3’
3’
corn (4/15)
corn (5/1)
corn (5/15)
corn (4/15)
corn (4/15)
corn (5/1)
corn (5/1)
corn (5/15)
corn (5/15)
North
Planning suggestions
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Put vine crops on the edge
Plant 3 rows of corn for pollination
Put tall plants on north side
Plant small amounts several times to
extent the harvest season
• 1,000 sq. ft. takes about 1 hr per week of
care
Other considerations
• Rather than rows, can plant broadcast (no
rows), but rows are easier to care for
• Consider equipment size for row spacing
• Double crop to use space efficiently –
Harvest radishes, peas, lettuce early then
plant late-season crops in same space
(peppers, beans, summer squash)
Develop a Garden Calendar
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January – look at seed catalogues
February – Order seeds
March – Plant peppers indoors, test soil
April – plant early season crops
May – Sept. – grow garden
Oct. – clean up garden
Unit 2. Planting a Garden
• Understanding soils – soils provide
support, water, and mineral nutrients
• Soil is composed of sand, silt, clay and
organic matter
• Soil has living organisms – worms,
insects, fungi, bacteria: some are pests,
some are beneficial
• If too much clay, add organic matter
Soil Chemistry
• Soil pH should be slightly acid (6.0 – 6.8)
– Too low: macronutrients are deficient
– Too high: micronutrients become toxic
• Macros: N, P, K, Ca, Mg
• Micros: Fe, Cu, Mn, B, S, Zn
• Most soils have enough of everything
except N,P,K – complete fertilizer
Soil Physical Characteristics
• Sand – large particles, good for water
drainage
• Clay – very small particles, holds lots of
nutrients, hard to dig, poor water
movement
• Silt – intermediate size, water moves
slowly
• Organic matter – holds water and provides
nutrients and supports micro-organisms
Buying plants & seeds
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Buy current season’s seeds
May have to order unusual varieties
Look for disease resistant varieties
Buy good-quality plants – look for new
shipments – avoid yellow or wilted plants
Artificial Soil Mixes
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Fewer disease problems than real soil
Usually contain fertilizer
Some brands better than others
I like “Mirical-Gro”, but others may be good
Usually contain peat, vermiculite & perlite
and fertilizer
Starting Plants Indoors
• Need warm sunny place
• Don’t start too early, plants will be potbound and “leggy”
• Transplant to pots when about 1.5” tall
• Put outdoors as soon as possible
Planting in the garden
• Cultivate the soil and incorporate fertilizer
and lime
• Use string to make straight rows
• Small seeds are barely covered, plant
large seeds 2 times their diameter in depth
• Thin plants to appropriate distance –
follow directions on the packet
Transplanting
• “Harden” plants by growing outdoors for
about a week
• Plant at about the same depth as in pot
• Remove peat-pot bottom and side
• Water
• Avoid hot sunny, windy days
3. While You wait – Plant Science
• Seeds – a seed is an embryo, a tiny plant
with root parts, a stem, and about 6
leaves. A seed coat protects the embryo
• Have a food supply until there is adequate
foliage to produce enough carbohydrate
• Endosperm and cotyledons (specialized
leaves) – starch (corn & wheat) or oil
(beans). Coconut “milk” is liquid
endosperm.
Two kinds of plants
• Monocots: one cotyledons – grasses
• Dicots: two cotyledons – beans, apple,
maple, tomato
Seeds and Seedling
Dicot and Monocot Seedling
Dicot Seedling
True leaf
Cotyledons
Conditions for seed germination
• Seeds are living organs
• Need Oxygen for respiration to generate
energy from food supplies
• Need Water (imbibition) for cell expansion
and for photosynthesis and biochemical
reactions
• Proper temperature – 45 degrees for
lettuce, 70 degrees for pepper
• Water and air enter through the seed coat
and carbon dioxide exit through the coat.
• Some seeds (lettuce) require light (red
light) to stimulation of hormones
• If planted too deep, leaves don’t reach
light before food reserves are used up.
• Some seeds have hard thick seed coats
and must be scarified (stratch the seed
coat) to allow water in.
Germination requirements
• Seed coats also contain “inhibitors”
and some need to soak to leach out
inhibitors.
• Some seeds require a chilling period
(vernalization) to break dormancy
(apple seeds need 1,000 hrs below
45 degrees F)
• Hormones (gibberellins) may
overcome dormancy
Common reasons for lack of
germination
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Improper soil temperature
Soil too dry
Seeds planted too deep
Seeds washed away
Damping-off disease (fungus)
Basic Plant Needs
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Light
Water
Mineral nutrients
Air (oxygen & carbon dioxide)
Proper temperature
Photosynthesis
• A biochemical reaction in the cells of
green tissues.
• Chlorophyll is the green pigment in
organelles called chloroplasts
Photosynthesis
• Requires the green pigment (chlorophyll) in the
chloroplast within the cell.
• The light cycle requires light for energy . Water
is split into hydrogen and oxygen.
• The dark cycle occurs in the dark or light where
hydrogen combines with carbon dioxide to form
glucose. Oxygen is passed through the
stomates.
• Glucose or sucrose transported through the
phloem throughout the plant.
Light for photosynthesis
• Chlorophyll absorbs light energy to convert
carbon dioxide and water into sugars.
Oxygen is also produced. Gases (oxygen,
carbon dioxide & water) pass in and out of
leaves through small holes called
stomates.
Respiration
• Within specialized organelles
(mitochondria) in the cells, sugars
are converted to energy which is
used for plant growth. Oxygen is
used and carbon dioxide is
produced.
Plant parts - Roots
• May store sugars (sugar beet, carrot) or
starch (woody roots, sweet potato)
• 2 types of roots
– Primary tap root: long strong roots
(some trees, carrots, dandelion)
– Fibrous roots: short thin roots arising
from larger roots (beans & tomato)
– Root hairs are extensions of cells on the
root surface (epidermal cells). These
very small structures absorb most of the
water and nutrients.
Root Motion
• Roots normally grow down. They are
sensitive to gravity (geotropism).
Stems
• Connect leaves and roots, and supports
leaves for light exposure. Similar to a pipe.
Water and mineral nutrients move up in
the xylem. Sugar solution moves down in
the phloem.
• Some stems store food – starch in potato,
starch in tree trunks in winter, sugar in
sugar cane.
Simplified stem cross-section
Epidermis -
Xylem
Phloem
Longitudinal section of a woody
stem
Stem function
• Epidermis – one layer of waxy cells
• Phloem – live cells
• Xylem – long dead cells lined up endto-end to produce a “pipe”
• Vascular Cambium – a cylinder several
cells thick between the phloem and
xylem. Responsible for diameter
increase: produces xylem cells to the
inside and phloem cells to the outside
Geotropism
• A plants grow in response to gravity
• Positive geotropism – roots bend
toward gravity
• Negative geotropism – stems bend
away from gravity
• Curvature is caused by unequal
growth on the 2 sides of the axis
Auxin – a plant hormone
• Produced in young leaves, shoot tips
(meristems) and seeds.
• Auxin moves with gravity, causes bud
dormancy and causes cell elongation
Growing tip
Tomato Gravitropism
Phototropism
Auxin
Auxin
Motion of stems
• Phototropism - Stems bend toward light.
Auxin is destroyed by light, so cells on the
dark side elongate and cause bending
toward light.
• Auxin produced in the shoot tip moves
down the stem and accumulates on the
lower side of the stem, so stems bend up.
• Root growth in inhibited by auxin. Auxin
accumulates on lower side, so roots grow
down
Apical dominance
• Buds actually are short stems with
about 6 leaves.
• Auxin moves from the apex down and
inhibits buds. Removing the apex
(pinching) allows the buds below the
apex to grow. This causes branching.
Carbohydrate transport
• Sugars can be used for energy or
converted to structural molecules such as
cellulose (cell walls), fats and proteins.
• Sugars move from areas of high
concentration (leaves) to areas of low
concentration in the phloem.
Flowers – modified stems
• At some point buds switch from vegetative
to reproductive – environmental cues.
• Flowers are reproductive structures and
attractive insects.
• Pollen produced on anthers is transferred
to the stigma, then germinates and grows
down the style to the ovary where the
sperm fertilizes egg to produce a seed.
Types of flowers
• Perfect flowers have both pistils and
stamens (peas, bean, tomato, apple)
• Imperfect flowers are either male or
female (cucumbers, melons, squash).
• Some species have male and female
plants (ginko trees).
Flower Parts
Fruits
• As ovules develop into seeds within the
ovary, the ovary swells and becomes
fleshy or hardens to protect the seeds.
Fruit helps seeds disseminate.
• Fleshy fruit (squash, tomato, grape) have
fleshy ovaries surrounding the seeds.
• Dry fruits have ovaries with thin, dry walls.
Corn, wheat, oats and each fruit is a single
seed. Beans are dry fruits with a nonfleshy
pod containing several seeds.
Seeds
Varieties of bean seeds
Tomato Fruit with Seeds
Bean fruit and seed
How do we make new plants?
Plant Propagation
• Sexual – from seeds: Allows a
species to survive by perpetuating
genetic variation
• Asexual or vegetative – produce new
plants from parts of a plant to
maintain genetic identify. Produces
clones.
Vegetative propagation
• Stems – potato, bulbs
• Cuttings – roots can be produced by
leaves or stems
• Grafting – join a scion variety onto a
rootstock
Match up
cambiums
scion
rootstock
Plant Life Cycle
Seeds geminate
Plant grows, matures, and flowers
Produces fruit and seeds
Plant dies
Annuals live 1 year (lettuce, beans)
Biennials flower second year, then die
(carrot, onion)
Perennials live many years (asparagus)
Plant improvement
• Natural selection: In the wild, individuals
within a species differ. Those with
characteristics enabling them to survive to
reproductive age pass on their genes to
the next generation.
• Man has domesticated plants and animals
by selecting individuals with the
characteristics we want.
Plant breeding
• Plant breeding: During the last century we
have controlled pollination to develop
hybrids or new varieties with outstanding
characteristics
• Examples include high yield, large fruit,
different flower colors, disease resistance.
• There is some concern that we have
reduced genetic variation too much, new
strains of disease may devastate a crop
Biotechnology
• A set of techniques used to study and
modify genes.
• Examples
– FLAVR SAVR tomato – doesn’t produce the
ripening hormone ethylene, so it can be
stored a long time before exposing it to
ethylene to cause ripening
– Some corn varieties contain the BT gene for
resistance to worms
Genetic Engineering
• Transferring specific genetic material from
one organism to another.
• Examples: Put the gene from a firefly into
a tobacco plant and the plant glows in the
dark.
• Put an antibacterial gene from a moth into
an apple tree to make it resistant to
bacteria.
Preserving genetic diversity
We want to save genetic variation to
use in breeding programs. USDA
maintains repositories for major
crops; both seeds and plants.
USDA funds plant collecting
expeditions to “centers of origin” for
major crop species
Interdependence (Ecology)
• All organisms are connected. Some
plants rely on animals to transfer
pollen and disseminate seed. Some
plants rely on fungi to improve root
function.
• Animals rely on plants to convert
solar energy (sun light) to chemical
energy (sugars)
Human impact on ecology
• Acid rain is killing the eastern forest
• Ozone, from car emissions, injures
some plant species
• Pesticides and other chemicals may
injure non-target organisms
• Global warming may alter the
distribution of organisms and
agricultural productivity
Hydroponics
• We can provide support and nutrients
for plants without soil
• Commercial greenhouse tomatoes
are often grown hydroponically in
shallow trays of flowing water
containing fertilizer.
• Most greenhouse crops are grown in
soiless mixes of sand, perlite,
vermiculite, and peat
Unit 4. Garden Care
• Soil fertility – At least 2 months before
planting contact local Extension office
for soil testing kit. Fertilize & lime
according to recommendations.
• Apply lime to raise soil pH and reduce
acidity (about 6.2 to 6.8)
• Apply complete fertilizer to provide
nitrogen, phosphorous, potassium
Organic Matter
Organic matter provides nutrients and
improves soil structure and water
holding capacity. Also encourages
many soil organisms – worms,
insects, fungi, bacteria
Sources – compost, manure, bone
meal
Garden Equipment
• Hoe, rake, trowel, watering can, hose,
short stakes and string to mark rows, long
stakes for supporting plants, hot caps,
sprayer, tiller
• Pesticides – read the label
– Store locked up
– Leave in original container
– Avoid freezing or hot environments
Frost
• Site selection – avoid low areas because
cold air is heavier than warm air and flows
down hill just like water.
• Tender plants, such as tomato, peppers,
squash are killed at about 30° F
• Cool season crops, such as cabbage,
broccoli tolerate a light frost (27° F), and
carrots, beets, lettuce tolerate 22° F
Frost protection
• Cover plants with hot caps,
newspaper tents, or mulch with straw
• Overhead irrigation
• Late season frost – harvest as much
as possible before the frost
How does irrigation work?
• As water freezes it releases heat. Ice
provides little insulation, so irrigation
must continue to freeze until the
temperature increases above 32° F
and all ice has melted
• Don’t irrigate when due point is low
and there is wind because
evaporation requires heat and heat
will be removed from plants
How do hot caps work?
Greenhouse effect
During the day short-wave solar
radiation is absorbed by soil and exits
the soil at night as long-wave
radiation. Hot caps provide a barrier
to long-wave lengths which are
redirected toward the soil. Frosts are
rare on cloudy nights because clouds
allow short waves, but not long
waves, to pass through.
Managing weeds
• Weeds are plants growing where they are
not wanted
• Weeds compete for light, water & nutrients
• Best to eliminate weeds when small
• Mechanical control – pull by hand, hoe,
cultivation. This must be done every 10 to
14 days depending on rain. Weed seeds
can remain dormant in soil for many years.
Mulch to control weeds
• Can use straw, shredded paper, thin
layer of grass clippings or plastic
• Also helps conserve water, reduces
soil erosion and keeps plants clean
• Apply mulch early, before weeds
come up
Herbicides
• Chemicals that control weeds
• May control grasses, broadleafs or
both
• Pre-emergent herbicides prevent seeds
germination
• Post-emergent herbicides kill plants on
contact
• Not recommended for home garden
Plant diseases
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Infection requires
– Susceptible host plant
– Presence of the pathogen
– Proper environment for disease
development
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Powdery mildew requires hot dry
conditions, and early blight on tomato
requires wet conditions
Viruses spread by insect vectors
Managing plant diseases
• Caused by fungi, bacteria, nematodes or
virus
• Select resistant varieties when possible
• Encourage quick drying – avoid shade,
control weeds, leave space between
plants
Controlling diseases
• Cultural control – good drying
conditions, resistant varieties, remove
diseased plants
• Fungicides and antibiotics – these are
preventative and must be applied
before infection occurs. Apply every
10 to 14 days to protect new growth
and replace residue washed off by
rain.
Diseases of squash
Powdery mildew
Septoria leaf spot
Virus
Non-pathogenic problems
• Sunscald heat injury to fruit
• Cold growing conditions can cause plants
to turn purple due to poor phosphorous
uptake
• Too much fertilizer can burn roots and
cause wilting
• Too much pesticide can damage leaves
Insect pests
• Many types of insects can feed on plants.
• Grubs (immature beetles) feed on roots
• Worms (immature moths) feed on leaves,
fruit, or tunnel into stems (borers)
• Maggots (immature flies) feed on fruit &
roots
• Beetles, aphids, and true bugs feed on
leaves
Japanese beetle life cycle
Controlling insects
• No resistant varieties, except for
genetically modified varieties of corn and
soybeans (BT genes)
• Use insecticides to kill insects
– Monitor plants every week
– Don’t apply until you see pests
– Use “soft’ materials that protect nontarget
organisms
Aphids
Corn Ear Worm Life Cycle
Adult
Pupae
Larvae
Natural vs. man-made pesticides
• All are poisonous and should be treated
with care
• Natural materials usually are broadspectrum and kill nontarget species, and
they must be applied more frequently
because they are less residual
• Insecticidal soaps are effective
• Many insects are beneficial and we want
to protect them
5. Harvest & storage
• Important to harvest vegetables at proper
stage. If many leafy vegetables are left too
long, they will produce flowers
• Peppers are ready when they are full size,
can wait and harvest them red
• Tomato can be harvested when just
beginning to turn red
• Cantaloupes are harvested when stem
slips off the melon
Other vegetables
• Zucchini, summer squash, and cucumbers
are harvested when fairly small (before
seeds enlarge) and need to be harvested
every day or two.
• Potatoes are harvested when leaves start
to die in late summer
• Onions are mature when leaves fall over
Storage
• Harvested plant parts are living tissues
and continue to respire. We want to slow
down respiration so the cells remain alive
• High humidity for leafy vegetables – put in
perforated poly bags
• Temperature is most important
– Most vegetables store well in the refrigerator
(about 40ºF)
– Peppers store at about 50ºF
Unit 6: Careers
• Without a college degree
– Farm, greenhouse, florist worker
– Assistant manager, retail market
– Landscape worker
• 2-yr Associate degree in plant science
– Assistant superintendent for golf course
– Farm & retail store manger
– Arborist, flower shop manager
4-yr degree programs
• Crop protection – entomology, plant
pathology, weed science
• Environmental sciences
• Ag economics - farm management, rural
development
• Horticulture, landscape architecture &
landscape contracting
• Plant genetics & plant breeding
Careers with B.S. degree
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Teach agriculture and science
Ag. Chemical sales, exterminator
Government agencies (USDA, DEP, EPA)
Manager of farms, retail centers,
nurseries, flower shop
• Landscape architect, Landscape
contractor, golf course superintendent
• Plant breeder
Careers with M.S. degree
• Research technician with chemical company,
university, USDA, private lab
• Plant breeder
• Produce wholesale & marketing
• International agriculture
• Government agencies
• Ag sales and marketing
• Extension agent
• Teach at community college
• Public gardens & arboreta
Careers with Ph.D.
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Academia (teach, research, extension)
Ag. Chemical company R&D
International agriculture
Plant breeder
Industrial research – Ag. Chemicals, plastics,
greenhouses
• Marketing
• Government agencies (USDA, EPA, DOE, DEP,
PDA)
Other considerations
• Rather than rows, can plant broadcast (no
rows), but rows are easier to care for
• Consider equipment size for row spacing
• Double crop to use space efficiently –
Harvest radishes, peas, lettuce early then
plant late-season crops in same space
(peppers, beans, summer squash)