Strawberry Growing Guide
Ground Preparation
Strawberries prefer a good, loamy, well drained soil that is rich in humus. Choose an open, sunny position which is sheltered from cold winds and late frosts.
On no account should planting be made on ground that has recently cropped strawberries or potatoes as this greatly increases the risk of disease build up. Prepare the ground prior to planting, incorporating well rotted garden compost or manure and remove all perennial weeds. Immediately prior to planting apply a fertilizer that is high in potash.
Planting
Planting should take place as soon as possible after arrival provided the soil is not over wet or frozen. If the roots are dry, soak them in tepid water for 1-2 hours.
Dig a hole large enough to spread the roots out, spacing the plants 12-16in (30-40cm) apart with a 75-90cm (30-36in) gap between rows. It is better to trim the roots if necessary rather than allow them to curl upwards.
It is important to set the central crown level with the soil surface. If the crown is buried or the roots are left exposed the plants will not do well and may eventually die. Firm the soil around each plant and water in. If soil conditions are heavy planting can be made on a raised bed or on a shallow 8cm (3in) ridge to improve drainage.
Cultivation
Contrary to popular opinion, it is not necessary to remove the flowers from summer fruiting strawberries in the first season. With the ‘perpetual’ varieties remove the flowers produced in the spring following the initial planting. Blossom appearing after mid June should be allowed to develop to produce a late summer and autumn crop. Cut off all off the runners unless you intend to propagate from the plants.
Once the fruit has set, apply a thick mulch of chipped bark or straw to retain moisture in the soil, suppress weeds and protect the fruit from soil splash. Alternatively use strawberry mats. As ‘perpetual’ varieties have an extended fruiting season avoid using straw as this can encourage fungal diseases when used over a long period.
Planting through black polythene is another useful method of protecting fruit. If the weather conditions are dry, water regularly whilst the fruit is swelling and ripening otherwise the strawberries will be of poor size and quality.
Treatment After Fruiting
When the plants have finished cropping, cut off all the old leaves about 10cm (4in) above the crowns. When fruiting has finished on the ‘perpetual’ varieties in the autumn, remove only the old leaves.
Apply a dressing of Sulphate of Potash at 15g per sq. m (½oz per sq. yard). In spring add a general fertilizer that is high in potash.
Forcing an Early Crop
Obviously it makes sense to use an early variety and autumn planting is advised. Plants can be covered with cloches, perforated polythene sheeting or fleece to hasten bud development and protect from cold weather.
If plants are completely covered remember to remove for periods particularly in fine spells as this will allow access for pollinating insects. Hand pollination, using a hairdryer or small paint brush to brush the flowers may be necessary, should insufficient pollinating insects be present.
Cultivation in Pots, Hanging Baskets, Strawberry Tubs & Growbags
Strawberry plants are well suited to cultivation in pots, hanging baskets, strawberry tubs and growbags. For best results, plant in the spring or summer with cold-stored plants.
Use a good quality multipurpose peat based compost and always use fresh compost to avoid disease infection. Do not incorporate any home made compost as it is likely to give disappointing results. With large containers or strawberry tubs, it is important to mix in one-third sharp sand or vermiculite to improve the drainage. Ensure that the compost mix is damp before planting.
When planting into a strawberry tub, fill the tub to just below the first level of planting holes with the damp compost mixture, making sure the compost is firmed down (to avoid sinking when watered). Insert the plants through the holes keeping the base of the crown in line with the soil level and the roots spread out over the compost. Repeat this process until all the levels are planted. Finish off by planting a few plants in the top of the tub. Sprinkle the plants lightly with water after planting.
When planting into growbags, 10 plants can be planted into a standard 1m growbag, staggered in herring-bone fashion. Loosen the compost in the growbag by giving it a good shake, mark the bag with the planting holes and cut a 5cm x 5cm (2in x 2in) X-shape at each position. Insert the roots of bare rooted plants into the compost with a large kitchen fork, making sure the roots are fully buried in the compost and the base of the crown is just resting on the surface. The roots need to be fully extended into the bag not folded up - if necessary trim excessively long roots. Sprinkle the plants with water after planting.
Strawberry plants grown in containers and growbags should be watered little and often. The most common cause of failure is overwatering young plants before they have had a chance to get established and allowing dormant plants to stand in waterlogged compost for long periods of time during the winter months. Growbags are easily watered using a Speed Feed Growbag Irrigator. The perforated watering tube slides neatly into the end of the growbag and a reservoir sits at one end. Alternatively insert two funnels in the middle of the bag made out of upturned cut-off plastic bottle tops. Apply a high potash feed to the plants when the fruits start to swell.
Overwinter the pots or growbags in a cold greenhouse, garage or garden shed, keeping the compost just moist. Do not overwater.
Crops treated in this way can be advanced by a couple of weeks and a mid May crop of strawberries is easily possible.
Pests & Diseases
Strawberry plants are susceptible to various soil borne diseases such as verticillium wilt and crown rot, so it is important they are planted on well drained soil and that a fresh site is used to avoid infection.
Grey mould (botrytis) and mildew can be a problem. Also watch out for red spider mite attacking plants grown under glass and vine weevil attacking containerised plants. Any chemicals should be used strictly as per the manufacturers instructions.