How to Care for Strawberries

How To Plant

It is important to plant strawberry plants to the correct depth - too low in the ground and the growing crown may rot, too high and the roots may dry out. Use the diagram on the left as a guide and also see the real picture below it.

The left hand plant in the diagram above is too high and the roots may dry out. The right hand plant in the diagram above is too low and the roots may rot, the middle plant is correct (as is the real picture to the right). The plants should be planted to the same depth as they have grown in their pots.

Care of Strawberries

Strawberries need lots of water until they are well established but don't water-log them. When established (around May), they should be OK without additional water. But when the fruits start to swell, begin to water again. Summer fruiting strawberries planted in spring and perpetual strawberries should have their first blooms pinched off to enable a good root system to establish. Strawberries planted in September  can be left to flower and fruit in their first summer.

Strawberries prefer a well-dug, free draining soil. If the soil is water-logged the plants will quickly attract a wide variety of mould disease. Feeding strawberries is not needed if you spread a layer of well-rotted compost around the plants in early spring. This will also help retain moisture without causing water logging.

If you want to feed the plants in the spring, use a weak solution of tomato feed which is high in potassium. Feeding with a nitrogen rich feed will only encourage leaf growth at the expense of fruit growth. The best time to feed the plants is when you see the fruits forming in late spring.

Because strawberries produce their fruit so quickly, it is not necessary to feed them - this makes it all the more important that the soil is prepared as described above.

In May, the plant will produce runners which have 'nodes' along them - these nodes are the beginning of new strawberry plants. The runners should be removed because they will sap the strength from the plant resulting in less fruit. 

Where the plants are being grown under cloches, remember to open them wide during the middle part of the day so that insects can reach the flowers and pollinate them.  

Care for Strawberries - Protecting the Fruit

As the fruit begins to develop, their weight will cause them to lay on the ground. Before this happens (but no earlier than necessary), cover the soil around the plants with either straw or black plastic. Where plastic is used, it can be kept in place with stones - small holes should be made in the plastic to allow drainage and stop water gathering on it. The plastic or straw will prevent the fruits from lying directly on the soil which will rot them.

If you have a bird population in your garden, the plants should be protected (when the fruits begin to swell) with light weight plastic netting. This should be held clear of the plants by tying it to short wooden posts and securing the netting to them. Wire mesh can also be used, held in place by canes at either corner.

Growing Strawberries in Containers

Strawberries can be grown in all sorts of containers and their needs are the same. We recommend the specially designed strawberry planters with rings of neat holes - there is no need for the fancy ones, a basic one will do the job well.

First, prepare a layer of drainage materials (hardcore, broken bricks etc.) covering the base of the container for an 2.5 cm (1in) high. Cover the drainage layer with potting compost to the level of the lowest ring of holes. 

For all but the smaller containers, it is vital to provide a central drainage core as well. Either make a wire mesh tube 10cm (4in) in diameter, and 10cm (4in) shorter than the height of the container; place it into the middle of the container and fill with drainage material. Alternatively use a plastic tube of the same diameter and height, place it in the container, fill with drainage material and remove the plastic tube when it is surrounded by potting compost.

Place the plants through the lowest level of rings and add more compost up to the next level of rings - continue until reaching the top. It is a good idea to gently firm the compost down as you go along, and water the compost at each level of rings to ensure it is fully moist.

Recommended Strawberry Varieties

Variety	Characteristic growth needs
Pajaro	Short variety. Popular for large berries and good flavour.
Chandler	Short variety. Yields heavily some large fruits, good flavour and firm skinned fruit
Selva	A neutral day variety producing small berries with good flavour and colour
Fern	A neutral day variety with heavy yield of large fruits with but lighter than all the others

Strawberry Diseases

1. Leaf spot
Caused by a fungi known as Mycosphaerellafragariae.

Occurrence
Leaf spot is one of the most common diseases of strawberries, occurring worldwide in most cultivars.

Symptoms
Initially, small, deep purple, round to irregularly shaped spots appear on the upper leaf surface. These enlarge to between 3–6 mm in diameter. They retain a dark red margin, but the centers turn brown, then grey and finally white.

Spots may join and kill the leaf. The fungus also attacks the petioles, stolons, fruit stalks and fruit as shallow black spots.

Sources of infection
Living and dead infected leaves from current and previous strawberry crops.

Spread
Splashing water from rain and overhead irrigation. Water is medium by which the spores are spread.

Favoured conditions
Extended wet periods, particularly in rain seasons.

Control
Remove and burn trash from the infected and previous crop. Avoid overhead irrigation.

2. Powdery mildew

Cause
The fungus Sphaerothecamacularis.

Occurrence
The disease affects all cultivated strawberries worldwide. No variety is resistant, but each differs in susceptibility.

Symptoms
An early symptom of the disease is upward curling of the leaf margins. This is followed by irregular, purple blotching on the upper leaf surfaces, often along major veins. The leaves feel brittle. This disease does not produce the masses of greyish white spores typical of powdery mildew on other crops. Powdery mildew can attack fruit at any stage.

Flowers do not set and eventually die. Immature fruit remain hard and do not ripen. Ripe or near ripe fruit become dull with prominent seeds.

Sources of infection
Trash from previous and current strawberry crops.

Spread
By wind.

Favoured conditions
Warm, humid conditions.

Control
Remove and burn trash from the previous crop. Apply protective fungicides and avoid overhead irrigation.

3.Grey mould

Cause
The fungus Botrytis cinerea.

Occurrence
This disease occurs on a wide range of flowers, vegetables and fruit, including strawberries.

Symptoms
The fungus will attack flowers, fruit, petioles, leaves and stems. Flowers and fruit stalks infected during flowering die rapidly. Green and ripe fruit develop brown rot. This spreads over the whole fruit, which becomes covered with masses of dry, greyish spores.

The rot may start on any portion of the fruit, but is found most frequently on the calyx end or on the sides of fruit touching other rotten fruit.

Sources of infection
The fungus over-winters on plant debris and infects flower parts, after which it either rots the fruit or remains inactive until the fruit ripens further. Spores, which are produced continuously throughout the fruiting season, germinate to infect plants.

Spread
By wind and splashing water from rain or overhead irrigation.

4.Phytophthora crown rot

Cause
The fungus Phytophthoranicotianae.

Occurrence
One of the main root pathogens affecting a wide range of crops.

Symptoms
The young leaves wilt suddenly and quickly spread to the entire plant.

Affected plants collapse and die within a few days. The crown has a reddish to brown colour and shows signs of rotting, usually starting from the top of the crown. Symptoms can appear within a few days of planting, or in spring when the plant is under stress. Initial symptoms are similar to Fusarium wilt.

Source of infection
Can be introduced either in planting material or from a reserve in the soil or from trash of previous crops.

Favored conditions
Found in a wide range of climates. The disease prefers poorly drained soils, high temperatures and plants under moisture stress.

Control
Improve soil drainage by growing plants on raised beds. Remove affected plants and burn to prevent the spread of the disease. Use clean certified plants. Soil fumigation can provide some control of the disease.

5.Fusarium wilt

Cause
The fungus Fusariumoxysporum.

Occurrence
This disease was first observed in south-eastern Queensland and is found in other countries. The disease only affects strawberries and most varieties are affected.

Symptoms
Infected plants wilt and die rapidly, particularly when carrying a heavy crop. The crown shows a distinct reddish brown discoloration. As the disease advances, the lower crown can decay.

Sources of infection
Soil where affected crops have been grown. The pathogen can survive in the soil for many years.

Spread
By infected planting material and trash.

Favoured conditions
High temperatures

Control
Improve drainage. Remove affected plants, including roots, and burn to prevent the spread of the disease. Plant only certified plants. Soil fumigation can help reduce the level of infection 

How to Propagate Strawberries
 

Propagating strawberries is simplicity itself. Look out for runners as in the picture on the left (click picture to enlarge it). Let the plantlet that forms at the tip of the runner root of its own accord. Then about three weeks after it has rooted, cut the runner, dig up the soil around the rooted plantlet and put it in a pot of normal potting compost.

Keep the potted strawberry plant in a light position, keep the soil moist and feed with a nitrogen based liquid fertiliser every two weeks. If the plants outgrow the pot (the roots start popping out of the base of the pot) then pot into a slightly larger pot.