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 spinach (3/20) lettuce(3/20) radishes (3/20) Onions (4/1) gr. beans (4/15) gr. beans(5/8) carrots (4/15) peppers (5/15) 6’ 2’ 2’ 3’ 4’ corn (4/15) corn (5/1) corn (5/15) 3’ corn (4/15) corn (5/1) corn (5/15) corn (4/15) corn (5/1) corn (5/15) 3’ North
Planning suggestions • 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 • 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 • 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 • 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 pot-bound 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
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 • Improper soil temperature • Soil too dry • Seeds planted too deep • Seeds washed away • Damping-off disease (fungus)
Basic Plant Needs • 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
Stem function • Epidermis – one layer of waxy cells • Phloem – live cells • Xylem – long dead cells lined up end-to-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
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).
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.