Protected strawberry production
The demand for "out of season" strawberries has increased substantially over the past few years. To meet this demand growers need to be able to extend their production and marketing season both in the spring and the autumn. The high price paid for good quality, home grown fruit at these times makes growing protected strawberries economically worthwhile.
One method of growing under protection which has increased in popularity is growing in peat bags. This method is costly and high yields together with high prices are required to offset the extra costs involved.
The growing house
Strawberries in peat bags can be grown either in glasshouses or polytunnels.
Strawberries in peat bags can be grown either in glasshouses or polytunnels.
The growing system
Strawberries are planted into peat bags either in January to give a crop in May or in June/July to give a small crop in August/September/October followed by a larger crop in May.
Strawberries are planted into peat bags either in January to give a crop in May or in June/July to give a small crop in August/September/October followed by a larger crop in May.
Varieties
The most widely grown variety is Elsanta which produces firm well flavoured berries. Unfortunately the variety can produce misshapen fruit under low temperatures.
The most widely grown variety is Elsanta which produces firm well flavoured berries. Unfortunately the variety can produce misshapen fruit under low temperatures.
Plant material
For protected cropping the following plant material may be used: crown plants, waiting bed plants and 15mm+ plants.
For protected cropping the following plant material may be used: crown plants, waiting bed plants and 15mm+ plants.
Plant density
For planting in January using crown plants a plant density of 8-10 plants/m2 is recommended.
For planting in January using crown plants a plant density of 8-10 plants/m2 is recommended.
Plant establishment
In order to achieve maximum yields it is essential to have 100% plant establishment and good early growth.
In order to achieve maximum yields it is essential to have 100% plant establishment and good early growth.
Irrigation
The bags are irrigated using either drip or trickle irrigation systems. The drip system is preferable but more expensive than the trickle system, and three drippers with an output of 2 litres/hour are recommended for each 0.90 m bag.
The bags are irrigated using either drip or trickle irrigation systems. The drip system is preferable but more expensive than the trickle system, and three drippers with an output of 2 litres/hour are recommended for each 0.90 m bag.
Nutrition
There will be sufficient nutrients in the bag to feed the plants for the initial few weeks after planting, after which liquid feeding will be required.
There will be sufficient nutrients in the bag to feed the plants for the initial few weeks after planting, after which liquid feeding will be required.
Pollination
As soon as the first flowers open bees should be introduced to assist in pollination.
As soon as the first flowers open bees should be introduced to assist in pollination.
Temperatures
For summer planted cold stored runners, the temperature should be kept as cool as possible prior to fruiting. Give as much ventilation as possible and if necessary damp down the floors and alley ways to try to keep the temperature below 24°C.
For summer planted cold stored runners, the temperature should be kept as cool as possible prior to fruiting. Give as much ventilation as possible and if necessary damp down the floors and alley ways to try to keep the temperature below 24°C.
Managing a crop
Strawberry plants grow vigorously under protection and leaf growth can shade developing fruits.
Strawberry plants grow vigorously under protection and leaf growth can shade developing fruits.
Diseases and pests
Botrytis or grey mould is a widespread and damaging disease of strawberries.
Botrytis or grey mould is a widespread and damaging disease of strawberries.
Post harvest treatment and frost damage
Once the leaf canopy begins to die off, usually by early to mid-December, the plants should be trimmed off and given a thorough fungicide drench against botrytis.
Once the leaf canopy begins to die off, usually by early to mid-December, the plants should be trimmed off and given a thorough fungicide drench against botrytis.
Further uses of bags
After cropping in the house, the bags can be used to take an outdoor crop in the following year. While berry quality and size will not be as good a significant return can be gained.
After cropping in the house, the bags can be used to take an outdoor crop in the following year. While berry quality and size will not be as good a significant return can be gained.
Summary
Ensure the support system is adequate.
Ensure the support system is adequate.