Protected Cultivation Techniques of Roses

• Roses (Rosa spp.) are one of the most important ornamental crops grown for cut flowers, loose flowers, and landscaping.
• Protected cultivation ensures year-round production, high-quality flowers, and reduces losses from pests, diseases, and adverse weather.
• Commonly grown under greenhouses, polyhouses, and shade net houses.

A. Importance of Protected Cultivation for Roses

• Ensures continuous flowering throughout the year.
• Protects plants from rain, hail, frost, and strong winds.
• Reduces pest and disease incidence, particularly fungal diseases such as powdery mildew and black spot.
• Improves flower quality: uniform size, color, and stem length.
• Enhances productivity per unit area.
• Enables efficient nutrient and water management through the use of fertigation.

B. Suitable Protected Structures

• Naturally ventilated polyhouses – simple, cost-effective, suitable for small-scale growers.

• Shade net houses (30–50% shading) – used in nurseries and young plants.
• Glasshouse or high-tech greenhouses – temperature, humidity, and light control for commercial cut-flower production.
• Walk-in tunnels – low-cost protection for seasonal flowering.

C. Site Selection

• Well-drained soil, loamy or sandy-loam with pH 6.0–6.8.
• Access to clean irrigation water.
• Area receiving 6–8 hours of sunlight/day.
• Shelter from strong winds and frost-prone zones.

D. Varieties

• The major varieties for green house are Top secret, Bordeaux, Golden Gates, Grand Galla, First Red, Konfetti, Mercedez, Ravel, Noblesse, Vivaldi, Gold Strike.

E. Propagation and Nursery Raising

• Propagation methods:

Stem cuttings: 15–20 cm healthy, semi-hardwood shoots.

Budding/grafting for hybrids and elite varieties.

Tissue culture for disease-free, uniform plants.

• Nursery media: Equal mix of sandy soil, farmyard manure, and cocopeat/vermiculite.
• Environmental conditions: Temperature: 20–28°C, Relative humidity: 70–80% and Shade nets during hot summer to prevent stress

F. Land Preparation

• Raised beds: 1–1.2 m width, 15–20 cm height.
• Soil solarization or biofungicide treatment before planting to control soil pathogens.
• Incorporate well-decomposed farmyard manure or compost (15–20 t/ha).
• Install drip irrigation lines before transplanting.

G. Planting

• Spacing:

Hybrid tea: 60–75 cm between plants, 90–120 cm between rows

Floribunda: 45–60 cm × 60–75 cm

Miniature: 30–45 cm × 30–45 cm

• Plant during early spring or late winter for best establishment.
• Transplant with intact root ball to avoid transplant shock.

H. Training and Pruning

• Training: Single main stem for Hybrid Tea; bushy growth for Floribunda.
• Pruning:

Remove weak, dead, or diseased shoots.

Cut back to 3–5 healthy buds after each harvest.

Shape plants for air circulation and light penetration.

• Topping and pinching: Encourage lateral branching and flowering.

I. Nutrient Management

• Base dressing: Well-decomposed FYM/compost before planting.
• Fertigation schedule (through drip irrigation): N: 150–200 kg/ha, P₂O₅: 60–80 kg/ha and K₂O: 150–200 kg/ha
• Micronutrients: Fe, Mn, Zn, B as foliar sprays.
• Adjust nutrients according to growth stage: Vegetative phase – higher nitrogen and Flowering/fruiting – higher phosphorus and potassium

J. Irrigation Management

• Drip irrigation recommended: 2–3 L/plant/day depending on growth stage.
• Maintain even soil moisture to avoid flower drop.
• Avoid waterlogging to reduce root rot and fungal diseases.

K. Environmental Management

• Temperature: 20–28°C (day), 15–18°C (night)
• Relative humidity: 60–70%
• Ventilation: Side and roof vents for air circulation
• Shade nets (30–50%) during summer to prevent heat stress
• Foggers/misters for cooling during hot months
• Heating in winter to prevent frost damage

L. Plant Growth Regulators (PGRs)

• Gibberellic acid (GA₃): Promote stem elongation and larger blooms.
• Cytokinins (BAP/Kinetin): Stimulate lateral bud growth.
• Auxins (NAA): Enhance rooting in cuttings.
• Ethephon: Uniform flower opening and stem elongation in cut-flower production.

M. Major Pests

• Aphids – sap-sucking; vector of viruses
• Thrips – cause bud and flower distortion
• Red spider mite – leaf yellowing and defoliation
• Whiteflies – vector for viral infections

Management:

• Insect-proof nets, sticky traps, neem oil sprays, release natural predators.

N. Major Diseases

• Powdery mildew (Oidium spp.)
• Black spot (Diplocarpon rosae)
• Botrytis blight (Botrytis cinerea)
• Rose mosaic virus

Management:

• Disease-free planting material
• Proper pruning for ventilation
• Fungicide sprays as per recommended schedule
• Avoid overwatering and high humidity

O. Harvesting

• First harvest: 6–8 months after planting for Hybrid Tea under protected conditions.
• Harvest early morning for maximum vase life.
• Cut flowers with stem length 50–60 cm for market or 25–30 cm for bouquet use.
• Harvest interval: Every 2–3 days during peak flowering.
• Postharvest: Keep flowers in 10–12°C water solution with sucrose and fungicide for extended shelf life.