Oklahoma Market Gardening School Season Extension: Plastic Mulch, Row Covers & Organic Mulch Jim Shrefler Area Extension Horticulturist Oklahoma Cooperative Extension

Oklahoma Market Gardening School Season Extension: Use of techniques and practices that enable planting or harvesting horticultural food crops at times other than those when outdoor field planting can be used. It may include reducing risks during any season having widely variable weather conditions.

Oklahoma Market Gardening School Why use season extension? Gardening fanatic Want a produce source for own use Need a produce source for business Opportunities for premium price or market presence

Oklahoma Market Gardening School Season Extension Practices Hoophouses – Recent work at Noble Foundation: A tremendous local resource! Create temporary conditions Start plants in greenhouse Grow in containers in the shade Open field practices

Oklahoma Market Gardening School Developing your system Think about plant growth needs and hazards to them Temperature of soil and air daily weekly Light Intensity Duration

Oklahoma Market Gardening School Developing your system (cont.) Think about plant growth needs and hazards to them Moisture soil air Wind

Oklahoma Market Gardening School Before getting started …. Why use season extension? You may have specific goals example – want tomatoes and lettuce for Thanksgiving Maybe you just want to get a jump on things in the spring Other reasons? Careful consideration of your needs will help you determine which techniques are best for you!

Oklahoma Market Gardening School General Reasons for SE Get crops started early in the spring Deal with adversity of summer conditions Growing and harvesting in the fall and winter

Oklahoma Market Gardening School Early planting in the spring Situation during February thru April Wide temperature variation 20 – 80 o F; April freeze is possible Soil is cool; soil warming lags air temperature increase Days are short but getting longer

Oklahoma Market Gardening School Early planting in the spring – Cold hardy crops Onions, lettuce, cabbage, carrots, English pea Can be planted in the open garden May benefit from floating row covers during freezes Black plastic mulch may speed plant growth Use transplants for onions, lettuce, & cole crops

Oklahoma Market Gardening School

Early planting in the spring – Moderately cool tolerant crops Sweet corn, Irish potato Germination will depend on soil temperature Chill injury with low 30s to 40 o F Use clear plastic for early soil warming Use row covers to protect from frosts / late freezes

Oklahoma Market Gardening School

Early planting in the spring – Non cool tolerant crops Tomato, cucurbits, snap beans Start as transplants Temperatures in 30s to 40s o F will arrest growth Use clear plastic for early soil warming Use row covers, hot caps, water walls to protect from frosts / late freezes Hoop house better than open field system

Oklahoma Market Gardening School

Deal with adversity of summer conditions Situation during April thru August Wide temperature variation possible: 30s (April) – 100+ o F Soil warming is adequate for most crops by May Days increase then decrease but are at the longest during this period Precipitation extremely variable

Oklahoma Market Gardening School Early planting for summer – Warm season crops that stop fruiting with extreme heat Tomato, pepper, cucumber, snap bean Objective: get crop producing before heat sets in Contrast with early production in hoop houses Start as transplants Use row covers, hot caps, water walls to protect from frosts / late freezes

Oklahoma Market Gardening School

Controlling growth conditions for variable summer weather Optimize conditions that favor crop growth Temperature, soil moisture, root zone Minimize possible hazards Excess soil water, excess soil heat, disease favoring conditions Possible practices to use: Raised planting beds Killed cover crop mulches Organic mulch: straw, paper Black, white, colored mulches & fabrics

Oklahoma Market Gardening School Controlling growth conditions: Optimize conditions that favor crop growth Temperature: allow soils to warm to 70 – 80 o F range Soil moisture: maintain soil moisture to favor an extensive root system Root zone: adequate tillage depth and raised beds favor a deep rooting zone

Oklahoma Market Gardening School

Controlling growth conditions: Minimize possible hazards Excess soil water: brief waterlogged conditions cause prolonged harm: tomato is especially susceptible but most vegetables affected Excess soil heat: crusted and bare dry soil is most susceptible to heat accumulation Disease favoring conditions: bare soil harbors organisms that may lead to plant diseases when plants contact soil or soil is splashed onto plants

Oklahoma Market Gardening School

Controlling growth conditions: Useful practices Raised planting beds Killed cover crop mulches Organic mulch: straw, paper Black, white, colored mulches Landscape fabrics

Oklahoma Market Gardening School

Fall and Winter Growing and Harvesting Adapt to adverse conditions High soil temperatures Short days Minimize possible hazards Early frosts and freezes High residual pest populations Possible practices to use: Shade producing structures Irrigation Transplants

Oklahoma Market Gardening School Fall and Winter Growing and Harvesting: Adapt to adverse conditions High soil temperatures Keep soil moist after seeding crops Shade soil surface until seedling emergence occurs Use transplants when feasible Short days Crop growth slows with shorter days and sunlight light intensity Smaller fruited crops may mature quicker (cherry tomato) Shade tolerant crop advantages (lettuce)

Oklahoma Market Gardening School Fall and Winter Growing and Harvesting: Minimize possible hazards Early frosts and freezes in fall Pepper, cucurbits, beans could be covered with row cover material May be less practical for staked crops sprinkler irrigation an option for light frosts High residual pest populations in fall Scout late season crops frequently Squash bugs a major cucurbit threat – row covers may also help here

Oklahoma Market Gardening School

Materials used in Season Extension: Plastic Mulch Black gets hot in sun! provides moderate soil heating Clear greatest soil heating of the plastic mulches condensation helps with heat retention

Oklahoma Market Gardening School Materials used in Season Extension: Plastic Mulch White may provide slight soil cooling sometimes combined with black or silver backing Colored red, blue, green, yellow specific uses for some Infrared-transmitting heating and weed control

Oklahoma Market Gardening School

Materials used in Season Extension: Non plastic Paper Mulch can provide benefits similar to black plastic biodegradeable special papers available shredded paper an option if available Organic mulches conserve moisture and suppress weeds insulate

Oklahoma Market Gardening School Materials used in Season Extension: Row Covers Types Clear polyethylene Spunbound polyester or polypropylene Properties vary in thickness, weight & size When selecting, consider crop temperature sensitivity growth habit pollination

Oklahoma Market Gardening School Materials used in Season Extension: Clear Row Covers A mini greenhouse Will get very hot in sunshine Some are vented favor crop and weed growth plan for controlling weeds use with black plastic mulch

Oklahoma Market Gardening School Materials used in Season Extension: Spunbound Covers Functions trap heat: 2-4 o F frost protection exclude insects block wind allow water passage Use 0.5 – 1.25 oz. per yard heavier gives too much shade thinner gives little protection

Oklahoma Market Gardening School Questions?