Strawberry is not a native plant in Indonesia, nevertheless it could grow and develop well in several mountain areas with cool climate. It was brought to Indonesia in 1980s and started to develop widely around 1990s. Strawberry has high economy value and is visually attractive. Currently, strawberry production is relatively low which makes it difficult to fulfill the increasing fruit demand.
Strawberry has a lot of health benefits including its anthocyanin, phenolic compound, and organic acid which are good for degenerative disease such as cancer, and cardiovascular. It also has ellagic acid particularly in the seeds and leaves that good for skin, whitening for teeth, eliminate bad breath, increased brainpower and vision.
Strawberry cultivation in the field is described as follows:
- Field Preparation and Planting
- Site Selection
Strawberry could be planted in the field, pot, or hydroponically as long as the environment condition is suitable.
- Temperature and Humidity
It grows well in cool climate in the areas between 1000-1500 above sea level that have temperature range of 14 – 24oC and relative humidity of 85-95%, with no extreme temperature and humidity.
- Soil and Planting media
It requires fertile and loose soil with good porosity and drainage. Soil with good organic matter and has sand in it is suitable for strawberry. The suitable pH is around 5,6-6,5.
- Light and Day length
Strawberry likes full sun with radiation length 8-10 hours/day.
- B. Soil tillage
- Weeding and Soil tillage
Before planting, weeds or wild plants should be cleaned with a hoe, lifted to its roots, then gathered in one place. Avoid the use of herbicides to keep the sustainability of soil organisms and soil fertility. The tilling is done to 30-40 cm in depth which also helps in cleaning weed and loosen the topsoil.
- Lime and manure application
After the soil loosen and leveled, spread 20-40 tonnes / ha of manure with 2 tons / ha of agricultural limestone (dolomite), then mixed with topsoil.
- Bedding and mulch installation
Make the beds with a width of 100 cm, height 40 cm, and the distance between beds = 50 cm, with the length depending on the size of the land. Put a black silver plastic mulch, and make a hole in the mulch as the planting hole with a distance of 40 x 30 or 50 x 50 or 50 x 40 cm. Let the mulch covers the beds in about 1 month before planting so that the reaction occurs between the soil, manure and lime.
- C. Seed Preparation
Propagation material of strawberry can be obtained in ICSFRI (from tissue culture), nursery owner in strawberry production areas or make it by yourself. Strawberry farmers can make their own seeds with stolon or runner. Parent used for seed multiplication should be prepared separately and not taken from the plant for production. Parent plants should be healthy, superior, have good production and fruit quality, aged about 6-10 months.
• Runner: clump parent plant is separated into several part (1 seedling, 1 runner), and then planted in polythene bags (18 x 15 cm) filled with media which is a mix of topsoil: husk (sand): manure/compost in a 1 : 1: 1 ratio. One month later, the seedling are ready for planting.
• Stolon: Stolon which already has two leaves and roots (roots candidate) is cut, root / radicula wrapped with moss and then planted in polythene bags or seed trays. Planting medium used is a mixture of topsoil: husk (sand): manure / compost in a 1: 1: 1 ratio. For fast growing plants, the seed needs to be given a plastic cover and maintained with regular watering so that the soil is always moist
- Available varieties in ICSFRI: Dorit, Local Berastagi, Sweet Charlie, Erlybright, Rosa Linda, Chandler, California, Holibert, Aerut, Festival
- Dig a hole on the field covered by mulch at 10-15 cm deep or adjusted according to the seed root length
- Take outthe seedsalong withthe media in polybagscarefully.
- Plant one seed per/hole, coveredwith soiland avoid burying the growingpoint.
- Do wateringregularly
- Plant Maintenance
- Rain Cover Installation
Strawberry cannot stand heavy rain. Therefore, install roof/shade made from translucent plastic. Plastic cover is mounted on a semicircular framework, made of bamboo bended between the side of the bed. On the morning when the weather is good, the plastic cover needs to be opened, then closed back in the afternoon to protect the plants from the rain at night.
Strawberry is sensitive to extreme changes in ground water levels. Therefore, do the watering regularly, 2-3 times a week except during the rainy season. Volume of watering to each plant is around 150 -250 cc, depend on the physical soil, air humidity and temperature.
At the time of flowering and early fruit formation, the water supply should be reduced to encourage generative growth so that the fruit can grow properly.
- Fertilizer Application
Fertilizer in the form of solution results in better growth and is more efficient than the one in solid form. Apply as follows:
1. vegetative growth phase (2 weeks after planting – before the age of 2 months):
Make a solution of 2 g of NPK fertilizer which has higher N (32-10-10) / 1 liter. Pour as much as 100-150 ml / plants around the roots of the plants every 2-4 weeks (depending on the vigour of the crops).
2. flowering Phase
Make a solution of 4 kg of NPK fertilizer that contains balanced elements (16-16-16) / 200 liters of water. Pour as much as 150-200 ml / plants around the roots of the plants every 2-4 weeks (depending on the vigour of the crops).
3. enlargement and fruit ripening Phase
Spray with fertilizers that contain high Potassium (KNO3) to increase the size of the fruit; to increase the sweetness spray with fertilizer containing magnesium (kieserite).
4. To prevent deficiency of micro elements, spray the plants with a complete micro fertilizer (multi micro, mikrota, etc.) especially during the vegetative growth based on recommended dose on the packaging of the fertilizers.
- Leaf pruning
Prune leaves showing disease symptom, old leaves, and leaves that are too dense to enhance efficient photosynthesis and prevent disease spread so that production and fruit quality could be maintained. Pruning old leaves will also encourage the growth of new leaves.
- Stolon Cutting
Cut or reduce the number of stolon if there is too many to make the growth focus on producing fruit, not for stolon growth.
- Fruit thinning
Dispose of the first flower and reduce the number of small size of fruit if it is too dense. Fruit thinning is done when the fruit is about the size of marble (aged 3-4 days after flowering).
Strawberry roots are relatively shallow so if weed is presence, it could cause competition for nutrient. Therefore, weeds should always be cleaned mechanically.
Those are the stages in cultivation of strawberries in the field. With the proper technology it is expected that production will increase so that strawberries can be developed more widely. (tr: BDM)