Horticultural uses of protected environments

Question 1

Describe use of protected environments for:

• Overwintering
• Production of plants
• Display of plants

Answer 1

• Overwintering:
  
  • overwintering of stock plants to provide suitable cutting material in early spring
  • providing minimal shelter for container grown plants to avoid frost damage
  • to force plant material in the spring for display purposes.
• Production of plants:
  
  • Providing the optimum conditions to maximise yield and to achieve optimum quality
  • to extend the growing season to enable both early and late cropping and provide continuity of supply
  • Propagation of tender and half-hardy plants
• Display:
  
  • display of tender plants during winter months

Question 2

Describe the production of cyclamen persicum (decorative pot plant) in a protected environment

Answer 2

• Propagation and establishment
  
  • Large seed with a hard seed coat, so soaked for 12 hours before sowing, and rinsed. Sow in trays or individual modules using John Innes seed compost. Seed sown 8cm spacing, covered (needs darkness for germination) and watered from below. Strict hygiene of growing media and equipment to reduce fungal diseases e.g. damping off. Germination takes approx 3 weeks at 15C temperature.
  • Once germinated a tuber will begin to form, pot into 13cm pots (don’t bury corm), using John Innes no.1 compost, grow on in cool greenhouse with 15c minimum night temperature and 25c maximum day temperature
• maintenance
  
  • 15c temperature. Ensure well ventilated ad kept moist by use of capillary irrigation. Plants should be spaced so leaves don’t touch. Watered from below to avoid fungal diseases like Botrytis. Feed every 2 weeks with balanced John Innes liquid fertiliser containing trace elements throughout growing season. After flowering and leaves fade reduce watering and feeding. Remove dead leaves and flowers to prevent fungal diseases. Pot into 14cm pots with JI no.3.
• Control of pests, disease and disorders
  
  • Pest: vine weevil - brown head, root eater. Severe cases eats all roots, plant collapses (as warm and lack of roots to take up water). Sciarid fly: small, long and almost transparent. Tunnel within root system and eat roots until they’re shredded. Adults flies can be seen on surface of growing media
  • Disease: cyclamen grey mould (Botrytis) - Maintain good hygiene and do not allow dead plant material to accumulate either on plants in the greenhouse or as rubbish. Remove dead leaves and flowers promptly and destroy. Maintain good air circulation and do not overcrowd plants

Question 3

Describe the production of Lycopersicon esculentum / Solanum lycopersicum (tomato - salad crop) in a protected environment

Answer 3

• Propagation and establishment
  
  • Seeds sown January - March. Seed either broadcast sown in a seed tray or in modules with one seed per module using seed growing compost. Sown 0.5cm deep in compost, maintain temp about 20C to aid germination. Potted on into 9cm pots when suitable size to handle (at least one set true leaves). Grown on about 16C.
• Planting
  
  • ​Once first truss of flowers have formed plants can be planted into grow bag, containers or border soil. Should be polanted at correct depth with minimal root disturbance, graded and well firmed.
  • Include base dressing before planting.
  • Plant support provided if indeterminate (vine-like / cordon) variety through bamboo canes or string system. Ensure correct watering and environmental control to ensure establishment. Monitor for P&D.
• maintenance
  
  • tie plants to bamboo canes, or wound around the string lines when layering to accommodate stem growth. Removing side shoots and de-leafing lower leaves to improve air movement and allow tomatoes to ripen. Water regularly, and ventilate. Feed with high potash fertiliser once first truss set to encourage flowering and fruiting.
  • Temperatures 15-18C, ventilation at 23C.
• Control of pests, disease and disorders
  
  • Pests: Aphids, whitefly, slugs, red spider mite
  • Diseases: Botrytis, verticillum wilt, tomato blight
  • Disorders: Blossom end rot (calcium deficiency, tomatoes turn brown and rot - add lime, don’t feed excessive potassium). Fruit splitting of tomatoes (occurs when rapid growth is induced following over-watering/wet conditions, after allowing the plants to dry out. Control: improving the water retention of the soil/growing media and by regular and careful watering.)

Question 4

Describe the production of Chrysanthemum x morifolium (cut flower) in a protected environment

Answer 4

• Propagation and establishment
  
  • softwood, tip stem cuttings 5-10cm length. Prepared by clean cut just below a node, remove lower 1/3 of leaves (leave 5 on stem). Medium strength hormone rooting powder applied to cutting base. Root in closed case, basal heat of 24c, takes 3 weeks.
  • Once rooted, plant in raised beds in border soil. Pinch out plant’s tip once they are established to encourage lateral growth to produce spray Chrysanthemums. Support by nets held by posts in the soil, raised as they grow.
• maintenance
  
  • To produce sprays remove apical bud to stop the plant and encourage lateral/bushy growth. For single blooms - Disbudding (removal of lateral buds by rubbing them out to leave terminal bud).
  • Disbudding i.e. removal of lateral buds by rubbing them out to leave the terminal bud.
  • Irrigation/watering: regularly, first overhead until flower buds form, then ground level by using a drip or capillary irrigation system, to provide moisture and stop wilting.
  • Nutrition application via base or top dressing or liquid feed through irrigation system e.g. watering can. Potassium fertiliser good when flowers buds forming.
• Control of pests, disease and disorders
  
  • Pest: Red Spider mite causes localised death of the leaf, as sap sucker/piercing. Results in fine leaf mottling. Severe cases silk strands are produced. Also aphids and whitefly - spray with fatty acid sprays.
  • Disease: Botrytis, fungal disease, affects soft plant tissue e.g. leaves, non-woody stems and flower buds of Chrysanthemum —seen as fuzzy grey mould. Prevalent in cool or humid conditions

Question 5

Describe the production of Impatiens walleriana (bedding plant) in a protected environment

Answer 5

• Propagation and establishment
  
  • small seed, broadcast sown in sterile trays using a seed compost with little or no fertiliser, good drainage and moisture retentive. Overfill seed tray, firm and level. Broadcast seed at density so not touching other seed (avoid damping off). Lightly cover seed, as requires light to germinate.
    Place seed trays in warm environment, basal temperature of 18c, keep moist, protected from direct sunlight.
  • Once seedlings large enough to handle, can prick out into modules or pots. Handle seedlings by cotyledons only to prevent damage. Use of dibber to avoid root damage. Prick out into John Innes No. 1 which has sufficient nutrients to sustain plant until planted out.
  • Grow on in 15-18c, water regularly until ready to be planted out, after risk of frost passed.
• maintenance
  
  • Harden off before planting out.
  • If necessary stop plant by pinching out growing tip to encourage branching
• Control of pests, disease and disorders
  
  • Damping off, control = use sterile equipment, don’t sow too densely, provide good air ventilation.
    Botrytis - grey fuzzy fungal mould on all aerial plant parts.

Question 6

Describe the production of Narcissus Tete a Tete (bulb for forcing) in a protected environment

Answer 6

• ‘Forcing’ refers to when a bulb is induced to flower out of season. Environmental conditions are identical to those they would experience outside but timeframe is compressed to produce blooms early.
• Forcing method: End of September/early October plant bulb in container without drainage holes, use bulb fibre so half of the bulb is out of the growing media. Place bulb container in a cold, moist environment at 4c temperature/refrigerator for 13 weeks to encourage root production. Following cold period, place container in a well lit, warm environment at 16c temperature for 4 weeks before the bulbs will flower.
  
  • Managing environment to prevent plant damage from disorders. Etiolated, weak/spindly growth corrected by improving light levels and correct bulb positioning.
• Control of pests, disease and disorders
  
  • Daffodil Basal Rot - bulb feel soft as brown rot develops. Pinkish-white fungus maybe visible between affected scales and on the basal plant. Bulb rots and appears ‘mummified’. If infected bulb planted may not flower, and have yellow foliage.
    Control: grow resistant cultivars e.g. Narcissus tazetta. Don’t store damaged/soft bulbs or replant Narcissus where infection occurred.

Question 7

Describe one horticultural use for a range of protective structures

Answer 7

• Greenhouse: propagation and production of a long main season crop of tomatoes or the production of a cut flower crop. Overwintering plants as has good light transmission and can be heated to provide frost protection for tender plants.
• Cold frame: propagation and production of young vegetable crops e.g. cabbage and for hardening off bedding plants. Easily constructed and low cost. Suitable for propagation by cuttings as no great height needed.
• Polythene tunnel: used to grow short season crops e.g. production of a crop of lettuce. Provides warm, humid environment suring spring and summer for optimum growth.
• Cloche: advance ripening of crops e.g. strawberries of for covering taller crops before they get established
• Conservatory: used to grow or display houseplants. Suitable for decorative display as likely to be attached to the house which enables occupants to enjoy plants being displayed.