High Tunnel v. Field Grown Cultural Practices

When to Plant

  • Considerations to determine appropriate planting dates include target market dates, plant type, and plant species
    • Examples of target market dates include specific holidays like Mothers Day vs. weekly delivery to a local florist
    • Annuals, depending on species, can be planted as early as late winter and as late as the summer
    • Biennials are often planted in the fall to accommodate their need for a cold treatment requirement to flower
    • Perennials, depending on the species, are planted in the spring or fall
  • Field Production Comparison: Spring planting in the field must wait until all danger of frost has past. However, high tunnels offer protection against spring frost and crops can survive being transplanted several weeks earlier

Plant Spacing

  • Plant spacing depends on several factors, including plant species, sensitivity to disease, method of staking, and method of harvesting. Spacing distances range from 4″ x 4″ to 12″ x 12″
  • Field Production Comparison: In general, annuals can be spaced from 4″ X 4″ to 18″ X 18″ apart and perennials from 12″ X 12″ to 24″ X 24″ apart

Crop Support

  • Crop support is important for production of cut flowers to reduce breakage and increase quality of cut flower stems
    • The most effective method to provide crop support is to use a plastic, nylon or wire mesh with 4-6″ openings that is supported horizontally with wood or metal stakes.
    • Depending on the final height of the stems and the species, two to three layers of support may be required
    • Staking plants individually is an inefficient use of labor and is usually unnecessary with properly planned use of mesh supports
  • Field Production Comparison: Mesh support material that is supported horizontally with wood or rebar stakes is also used extensively in field production


  • Drip irrigation is the preferred method for watering cut flowers in high tunnels
    • There are several types of drip irrigation, but use of T-Tape or turbulent twin wall tape is very common
    • Field Production Comparison: Drip irrigation is also widely recommended over overhead watering for field production. Field-produced cut flowers will also obtain moisture from rainfall: this is often a major drawback because wet foliage contributes to foliar disease and heavy rains can damage flowers and stems which decreases quantity

Nutrition Requirements

  • Cut flowers have high fertility requirements
    • Fertilizer can be applied pre-plant as a granular formulation or during production as a soluable feed
    • Higher rates of nutrition are required during the initial stages of plant growth when vegetative growth is active, but as harvest approaches lower rates if soluable fertilizer are applied
  • Field
    Production Comparison:
    Fertilization rate also corresponds to the stage of plant development; however, heavy rains may leach nutrients from soil in a field production situation

Insect & Mite Control

  • Major insect pests of cut flowers produced in high tunnels are aphids, spider mites, thrips, and grasshoppers
  • Other pests include cutworms and leafminers
  • Because plastic coverings typically contain a UV-block to minimize polyethylene degradation, bees, which require ultra-violet light to perceive pollen, may not find flowers in high tunnels
    • This could be advantageous for crops like snapdragons where florets die after pollination
  • Field Production Comparison: The same insect pests will thrive in the field; bees will readily pollinate flowers

Disease Control & Infectious Disorders

  • Infectious disorders are diseases caused by bacteria, fungi, viruses or insects
  • Some commonly found in cut flower production include:
  • Root Rots
    • Fusarium, Pythium, Rhizoctonia, Phytophthora
  • Stem/Crown Rots
    • Botrytis, Rhizoctonia, brown rose canker, Sclerotinia
  • Foliar fungus diseases are the most serious problem on cut flowers
    • Leaf Spots is a broad category denoting diseases that disfigure foliage
    • Bacterial Leaf Spots thrive in warm moist conditions and spread by water splash, insects, or other physical manipulation
    • Fungal Leaf Spots are caused by Botrytis, Alternaria, Septoria and thrive in cool periods
    • Rusts are also a fungus, and typically target specific species and cultivars
    • Downy mildew is found on the underside of leaves: spores can remain in the soil for many years, so remove infected plants as soon as possible, provide adequate spacing, and avoid watering leaf surfaces
    • Powdery mildew is the most prevalent and serious disease because it can disfigure foliage and flowers; its growth is encouraged by high humidity conditions
  • Viruses are host specific: however, some have a very broad host range such asthetospovirusimpatiensnecrotic spot virus (INSV)
    • Viruses are spread through propagation and insect vectors
    • Control of viruses is limited to removing the infected plant material and controlling insect populations
  • Phytoplasma is the casual agent of the disease commonly known as aster yellows that affects a number of annual and perennial cut flowers
    • Aster yellows is vectored by the aster leafhopper; control of the insect and removal of the infected plant material is the best form of control
  • Field Production Comparison: Cut flowers are subject to the same diseases in the field. Relative humidity is usually higher in high tunnels which may contribute to higher incidence of mildews. However, wet foliage and water-logged soils resulting from heavy rains may increase incidence of root rots during filed production



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