How to Raise Raspberries in a Greenhouse

Raspberries are produced on tall canes that may grow up to 8 feet in height. The plants may sucker and spread in the garden, which makes them perfect candidates for containers or pots. Temperatures below 5 degrees Fahrenheit will kill most raspberries, so cold-climate gardeners would be wise to raise their berries in a green house. The biggest problems with greenhouse production are the height of the plants and pollination. Raspberries will also need containers that provide them with enough root space, and a well-draining planting medium. A heated greenhouse will produce the earliest berries, but an unheated one will provide shelter and protect berries from cold temperatures.

Sand
Peat
Perlite
Vermiculite
2-gallon pots
Raspberry starts
Water
Trellises
Fan
Heater
Watering can
High-potassium fertilizer (5-11-26)
All-purpose fertilizer (15-16-17)
Small paint brush

Instructions

- 1
  Fill 2-gallon pots with equal parts sand, peat, perlite and vermiculite. Plant the raspberry starts so the canes are out of the planting medium and only the roots are covered. Water thoroughly until the medium is evenly moistened.
- 2
  Leave the pots outdoors, if possible, in fall. Raspberries need to experience chilling to produce flowers and fruit. The minimum amount of chilling is about 1,000 hours. Plants will flower in the greenhouse six to eight weeks after experiencing chill temperatures.
- 3
  Outfit the greenhouse with a fan and heater. Temperatures must reach between 55 and 65 degrees Fahrenheit. The fan helps circulate the air to prevent humidity buildup which can cause fungal problems.
- 4
  Bring the plants into the greenhouse. Provide 22 inches of space between pots, and 3 feet between rows. Insert trellis material into the pots or arrange it next to them so the canes will have something to lean on as they grow.
- 5
  Fertilize each time you water with an alternate product. Use a high-potassium fertilizer in the ratio 5-11-26 at irrigation, and the next time use an all-purpose fertilizer. Dilute them in the irrigation water at the rate the packaging recommends.
- 6
  Hand pollinate the flowers when they arrive. Dip a small paintbrush into a flower. Transfer the pollen to another flower. Continue until all the flowers have been pollinated. Do this daily during the flowering period so you don't miss any. Harvest berries as soon as they are a rich, deep color.

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