The strawberry was initially a plant that grew in mild temperatures but has adapted well in warmer regions.
It has become popular around the world and is grown in nearly every country, due to the breeding of new varieties that can grow under a wide range of climatic conditions.
Strawberry, being mainly a fresh market product, can be very profitable, if you are able to meet the challenges involved in growing strawberries.
The following varieties are available;
Vigorous and high yielding, the chandler strawberry variety produces very desirable strawberries. Chandler strawberries are very large, and firm and produce within 60 to 75 days. The shape ranges from long and wedge-like shape to being conical in shape and large in size. They have brilliant red colour and glossy look, with an exceptional flavour.
Chandler strawberries are good for export or fresh market. They are very good for freezing.
The Douglas strawberry is a vigorous plant with clear forage with a semi-erect habit. It produces elongated berries that are conical in shape and orange-red in colour. The berries have firm red flesh, with a pink centre. They have good taste and resistance to transport damages. The Douglas strawberry gives high yields.
The Aiko strawberry produces uniform large conical berries, with a pointed end. They have firm pale red firm flesh that is slightly sweet. They are resistant to transport damages and have high yields.
The Pajaro strawberry is a short day variety, that gives berries that are symmetrical in shape. It is late maturing, with low production, making it not popular.
The Fern strawberry is a day-neutral variety that is high yielding with firm skin and sweet berry. It is good for fresh markets and processing.
The Cambridge strawberries produce many runners, small-sized sweet berries. It is resistant to most diseases.
Strawberries grow well at altitudes of between 1250 and 2200 metres above sea level, east of the rift valley.
They require a well-distributed rainfall of 1200mm. Less than this will need irrigation at the rate of 25mm per week. The strawberry plant is not drought tolerant. Drip irrigation increases yields improve the size and appearance of the berries and prolong the harvest period.
Strawberries grow in a wide range of well-drained soils, although deep sandy soils that are rich in humus are most ideal.
The soil should have a good capacity for retaining moisture. The soil drainage should be good enough to keep the water level at least 80 to 100 cm below the soil surface. Poor drainage makes strawberries weak and susceptible to diseases. The soil PH range should be 5.5 and 6.5. Saline soils should be avoided.
In order to break the hard pan and improve soil structure, double digging is encouraged. The beds should be one metre wide and any desirable length. Leave a path of 50cm wide between the beds. Incorporate 15 kilogrammes of well-composted manure per metre squared. The beds should be levelled and watering should be done on the whole bed in preparation for planting. The bed preparation should be done one month before the date for planting.
Strawberries are vegetatively propagated, using splits and runners. Splits are the most used method. Seed are rarely used because they are not viable. The viable seeds take a long time before reaching the recommended height for transplanting.
Before planting, work the soil, so that there is a deep and reasonably loose planting bed.
Treating strawberry splits
Before planting the splits, trim the leaves, and roots and dip the split in a fungicide solution 24 hours before planting. Examples of fungicides used to prevent fungal infections are ridomil, pearl, cotaf, and master.
Dig planting holes that are approximately 7.5 cm deep, 30 cm between rows, and 30cm between plants. With this spacing, you will be able to plant 75,000 plants per hectare. Apply two grammes per hole of a recommended nematicide.
The strawberry crown is very short and cannot tolerate deep planting. Roots should not be allowed to dry. Make sure the crown, in the middle, is level with the soil.
Soil should be watered after planting to set the strawberry plants into the soil. Avoid watering the plants directly.
Plant the strawberries in soils that have no weeds. After planting, weekly cultivation is needed to remove weeds when they are small. Remove all diseased runners and leaves regularly.
Do not apply fertiliser during planting, in order to avoid the splits getting dehydrated. This is because they go into a dormant state for 14 days after planting.
Within the first month, remove the first and second flowers to prevent premature fruiting and give the plants time to develop roots.
After 30 days, fix CAN fertiliser, 10gms (one tablespoon), per hole, in between the plants. Fertilisers are used to maintain soil fertility and maximise plant growth and fruit production.
Strawberries are heavy feeders, hence they need to be boosted with foliar feeds such as Easygrow vegetative, flower and fruit, and calcium to firm the skin of the fruit and decrease fruit deformities.
Strawberries are self-pollinating, but cross-pollinating will achieve better yields.
Mulching will help conserve ground moisture, keep the fruits clean and add humus to the soil. Avoid applying mulch when the plants are too young.
If using plastic mulch paper, do not use the black one, as it will raise soil temperatures. Optimal fruit production requires cool soil.
During the cold and rainy seasons, the strawberries go into a rest period. Remove all the old and diseased leaves to reduce infection from diseases, reduce pests, allow for aeration and allow regrowth of the foliage. Burn all the removed leaves outside the field.
Cut off runners regularly, except those needed for fruiting. After seven months, thin the plants, leaving the mother and three daughters.
During the first month of planting, water daily, in the evening for 30 days. This will help in root establishment and initial vegetative growth.
From the second month onwards, after applying mulch, water twice or thrice a week depending on the weather.
The best method for watering is through drip irrigation, a watering can or a low-pressure hose pipe. The high-pressure sprinkler will cause flower abortion, and fruit bruises and will contribute to fungal infections.
The maturity of strawberries depends on the temperatures during the growth period. The warmer the temperature, the faster the maturity.
The maturity period ranges from 75 to 90 days depending on the variety.
Strawberries should be picked when they are completely ripe because strawberries do not continue to ripen once harvested. If you do not pick the ripe berries, they will become overripe or rotten by the next picking.
Avoid crushing the fruit when picking, by using a firm clean container to put the strawberries after picking.
This is done to remove damaged, unripe and dirty fruits. Remove all the fruits without the calyx.
Precooling is done to remove the field heat in order to minimise deterioration. Small-scale farmers can use charcoal coolers. For markets that are far, forced air precooling is needed.
Strawberries are graded according to sizes and shapes, depending on the targeted market.
Grade 1 – 6-9 fruits per punnet
Grade 2 – 15 to 25 fruits per punnet
Grade 3 – 28 to 32 fruits per punnet
Any smaller strawberries are kept for processing into jam and juice.
Strawberries are packed into punnets, ready for delivery to the market.
The yield of strawberries per hectare
The yield for strawberries per hectare is 25,000 kilogrammes for the first year, 18,750 kilogrammes the second year and 12,500 the third year respectively. It is recommended to replant by the end of the third year.