Strawberries in the Home Garden: A Guide For Atlantic Canada

The strawberry, considered by many people to be their favourite berry crop, is ideally suited for the home garden. A small plot of land can produce all the strawberries required for an average size family. Growing strawberries can be a satisfying and rewarding pastime.

To be a successful grower, however, you should remember that the strawberry plant responds to length of day and temperature. During the long daylight period of late spring and early summer, plants develop runners which produce new plants. When the day-length shortens in late summer, the development of new runners stops and flowers begin to form in the crown for the next summer's crop. Temperatures above 18°C favor runner production while cooler temperatures favour floral development.

You can meet the plant's basic needs by following these suggestions.

SOIL

Good soil is important. Deep sandy loam soils, well supplied with humus, are ideal. They drain well yet hold moisture, which is essential for high yields. Coarse sandy and gravelly soils need additional nutrients and water to support a strawberry crop, but with care, success can be achieved. Poorly drained clay soils are the least suitable because they are difficult to manage and strawberry roots will not grow well in a continuously wet soil. In clay soils, growing strawberries on ridges or raised beds is recommended.

SOIL PREPARATION

Strawberries planted in well prepared soil should produce fruit for at least five years. An adequate supply of organic matter in the soil is important. Organic matter improves soil structure, provides nutrients, promotes the growth of helpful soil organisms, and increases the water-holding capacity of the soil. If the organic matter content of the soil is low, it can be improved prior to planting by applying a generous amount of weed-free animal manure, peat moss, or compost. A green-manure crop such as oats, clover or buckwheat, grown and incorporated in the soil the year prior to planting, is an excellent method of soil improvement. Provincial departments of agriculture will analyze soil samples and advise on limestone and fertilizer requirements.

USE OF LIMESTONE

Strawberries are best suited to soils ranging in pH from 5.5 to 6.5. Soils having a pH range of 4.0 to 5.0 are too acidic and may be low in calcium and magnesium. Spreading dolomitic limestone results in an increase of soil pH and makes calcium and magnesium more available. If dolomitic limestone is required, you should spread it and work it into the soil one year before planting. A general recommendation for acidic soils is 1 kg lime/m 2 .

VARIETIES

The list of recommended varieties is frequently revised so contact your nearest agricultural office before buying. Varieties presently recommended for the home garden are:

Veestar (early)

Fruit is small to medium in size, medium red, quite soft, with good flavour. 'Veestar' is suitable fresh for dessert, for freezing, and for jam.

Annapolis (early)

Fruit is large, light to medium red and firm. Recommended as an early fresh dessert variety when resistance to red stele is required. Red stele root rot may be a problem for susceptible varieties on poorly drained soils.

Sable (early)

Fruit is large, medium red and medium firm with good flavour. 'Sable' is suitable fresh for dessert, for freezing, and for jam. It is a good choice for poorly drained soils.

Fig. 1 - "Cavendish" strawberry.

Cavendish (early midseason)

Fruit is very large (Fig. 1), medium to dark red, with good flavour. Pollination is improved if grown beside an early cultivar.

Kent (midseason)

Fruit is large, medium red and firm. Noted for its exceptional yields.

Mira (late midseason)

Fruit is large, light to medium red and firm. High yields can be expected, even on poorly drained soils. "Mira" exhibits a greater drought tolerance than many other varieties.

Bounty (late)

Fruit is large in early pickings but small in later ones, medium red, medium firm, very good flavour, hulls easily. Suitable for fresh dessert and freezing. A good jam variety.

EVERBEARING VARIETIES

All of the strawberry varieties described above are short-day plants, commonly known as June-bearers. These varieties initiate flower-bud formation in late summer when day-length shortens. Recently, improved types of everbearing strawberries have become available. These types are known as day-neutral varieties because they are relatively insensitive to day-length. They form flower-buds all summer long, provided temperatures are not too high. Under the climatic conditions of Atlantic Canada, fruit production is concentrated in early July and September. The September crop can be advanced to August by removing flower stalks in early June, thus forfeiting the first crop.

The recommended day-neutral varieties are 'Tribute' and 'Tristar'. 'Tristar' is considered better for the home garden due to its superior flavour.

Day-neutrals produce fewer runners than June-bearers. A suggested planting system is a two-year cycle. Plant in spring of year 1 as early as soil can be worked. Space the rows 80 cm apart and the plants in the row 30 cm apart. Apply a 2 cm thick layer of straw to control weeds, conserve water, and to keep the berries clean. Remove flowers for 6 weeks after planting to encourage runnering and to promote plant establishment. As runner plants form, insert them through the mulch into the soil to ensure rooting. Fruiting will continue into October if plants are protected from frost by a plastic row cover or cloche. Plants should be covered with a straw mulch for winter protection.

In spring of year 2 the gardener must decide whether to allow the plants to fruit in early July or to maximize the autumn crop. If the gardener also grows June-bearers, the removal of the first flush of flowers on the day-neutrals, is preferable. Fruit will then be produced from August to October. It is important to consider that day-neutral strawberries are more demanding for nutrients than June-bearers, and supplemental fertilizer applied throughout the growing season would be beneficial. Insect pests are generally more severe on day-neutral varieties than June-bearers. Fruit size and productivity decline with repeated cropping cycles and it is recommended that a new planting be started in the spring of year 3.

PLANTING STOCK

Plant certified stock. Several nurseries in Atlantic Canada specialize in growing certified strawberry plants from virus-indexed stock. They co-operate with the provincial and federal departments of agriculture to produce healthy stock for planting.

TIME OF PLANTING

Plant in the early spring to have runner plants by early summer. Early formed runner plants produce more fruit than those formed during late summer and fall.

HANDLING PLANTS

Obtain plants as close to planting time as possible. If you cannot plant immediately after receiving the plants, keep them cool and shaded from the sun. If there is a long delay, store them at a temperature above freezing but below 4.5°C. If a cold room is not available, dig a narrow trench in well drained soil, space the plants in the trench and firm the soil around the roots. Protect the tops of the plants from direct sunlight and wind. Do not allow plants to dry out during planting. Be extra careful in handling plants when it is sunny and windy. The very fine root system will dry out within a few minutes if not covered. If the roots are dry, place them in water just long enough to wet them and then allow the excess water to drain off. Do not leave the plants submerged in water.

Fig. 2- The first plant (at left) is set at the correct depth with roots straight downwards and spread. The second is too deep and the third is too shallow. The roots of the fourth plant are bent and remain near the surface.

PLANTING SYSTEMS

There are many planting systems. The one best suited to the Atlantic Provinces is the matted row. Space the rows 1.4 m apart and the plants in the row 50 cm apart. Set plants so that the midpoint of the crown is level with the soil surface (Fig. 2) and the roots are straight down and somewhat spread. If the plant is set too deep, runnering will be delayed and the growing point of the crown may rot. If set too shallow, the crown and the tops of the roots will dry out. Encourage the runners from these plants to root, by keeping them in contact with moist soil, until the desired number of plants develop.

CARE OF THE PLANTING

The yield and quality of the crop depend largely on the first summer's growth and runner development, so pay special attention to cultural operations such as fertilization, cultivation and weed control to encourage development of strong plants and early runners. Watering may be particularly beneficial during the establishment phase.

APPLICATION OF FERTILIZER

Apply a commercial fertilizer 4 to 6 weeks after planting. A general guide is 200 g of 6-12-12 or 10-10-10 fertilizer per 6 m row, spread along both sides of the row and incorporated with a hoe. If a more concentrated fertilizer such as 17-17-17 is used, reduce the amount proportionately. An application of nitrogen fertilizer such as ammonium nitrate (34-0-0) at a rate of 50 g per 6 m row in late August will improve the formation of flower buds. Remember to brush fertilizer off the foliage immediately after it is applied, to prevent injury.

CULTIVATION AND WEED CONTROL

Frequent cultivation of the planting by hand hoeing is needed to control weeds and to keep the soil loose enough for the runners to root. The newly set plants should be cultivated as soon as weeds begin to compete or if the soil becomes compacted by heavy rain. The strawberry plant is very shallow rooted and cultivation should be only deep enough to destroy the weeds. Avoid throwing soil over or pulling it away from the crowns of the plants. Chemical herbicides are not recommended for the home gardener.

BLOSSOM REMOVAL

Removing the flower stalks on newly set plants results in earlier and increased runnering. The blossoms should be removed as soon as they appear.

RUNNER SPACING AND ROW WIDTH

A serious fault of the wide matted row is that too many plants can develop. If this happens, yield and berry size are reduced because of crowding and competition for water, nutrients and light. Also, pollination may be poor in crowded rows (Fig. 3). Maintain a spacing of 10 to 15 cm between runner plants. Remove all surplus runners after the desired spacing has been reached. The early runners produce the most fruit. A narrow plant row of 45 cm is recommended. This width allows easy weeding and harvesting. In comparison to wider rows, it produces larger fruit and is usually less infected with foliar and fruit diseases. Rows should be narrowed, if necessary, in early October of the planting year.

MULCHING

Strawberry plants must be mulched to prevent winter damage. If plants are unprotected, low winter temperatures injure roots, fruit buds and crown tissues. Alternate freezing and thawing of the soil may heave the plants and break the roots. Plants with damaged root systems suffer for moisture during the harvest period. Furthermore, unmulched plants will begin to grow too early in the spring and early blossoms and leaves may be subject to frost damage (Fig. 4). Covering the plants with a light-weight cloth or row cover can give a few degrees of frost protection from late frosts.

Oat and rye straw are ideal for mulch. Straw sometimes contains grain and weed seeds that are likely to grow and become troublesome in the spring. Select straw that is free of grain and weed seeds. Do not use old hay because it usually contains too many weed seeds.

Fig. 3 - Deformed fruit may be caused by frost damage, inadequate pollination, or insects.

Fig. 4 - Frost has killed the pistils and stamens on the left flower. No berry would form after this degree of injury.

Time of mulching is important! It is recommended that you apply the mulch after the first hard frost. A light frost will not hurt the plants, but they should be protected from temperatures below -9°C. The exact temperatures at which injury will occur varies for each plant. The older, larger plants show greater resistance to injury than do the younger or weaker plants. Much of the so-called blackroot and root rot of strawberries is started by winter injury to the roots. Early spreading of mulch, before the plants have become fully dormant, may cause severe damage to leaves and crown. In most of the Atlantic Region, November 15 seems to be a good date to apply the mulch, but in mild years a later date is preferable. By this time, the plants have usually been exposed to several frosty nights, growth has stopped, and there is little danger of injury or smothering. Spread the mulch uniformly over the rows of plants. A mulch that is 5 cm thick when settled, will provide the necessary protection.

Remove mulch from the plants in the spring when new leaf growth begins and foliage starts to turn light yellow. Do not remove all mulch. Leave one-third of the mulch over the bed; the plants will grow up through it. This will help to control weed growth and keep the berries clean during harvest. Place excess mulch in the row aisles. It can be used again to protect the plants if frost conditions threaten.

RENOVATION

Strawberry plantings can be maintained for 5 years or more if properly managed. Start renovating the day after picking is finished. First, mow off the foliage with a lawnmower. Ensure that the blade is set high enough to avoid damaging the crowns. Leaves should be removed or tilled into the aisles. Narrow the rows to 45 cm and then thin plants within the row leaving a space of 10 to15 cm between plants. This is a good time to remove any weeds, particularly grasses, in the rows. Apply a balanced fertilizer to the rows, such as 10-10-10 at 300 g per 6 m row, then spread fine soil or compost to a depth of 1 cm in the row. Irrigate to promote fertilizer uptake and to stimulate growth. Rigorous renovation with good weed control will extend the life of your strawberry patch many years.

PEST CONTROL

The important pests which attack strawberries are fungal diseases such as leaf spot, leaf scorch, mildew, and fruit rot, and insects such as weevils, plant bugs, and mites. A good measure of disease control can be attained through proper sanitation, by not allowing the planting to become too dense, and by picking all fruit before they become over-ripe. For chemical controls, consult the Home Garden Protection Guide for Strawberries - AAC Pub. 1001.

Photographs by A.T. Lightfoot and A.R. Jamieson.
Fig. 5 - A well grown matted row will produce a large quantity of good quality strawberries. Straw mulch between the rows serves to conserve moisture, suppress weeds and keep the fruit clean.

In recent years in suburban areas, raccoons have become major pests of strawberries. Annoyingly, they pick berries one or two days before you would consider them fully ripe. Although difficult to control, raccoons can be excluded by enclosing the planting with netting.

YIELD

A 6 m row of vigorous plants (Fig. 5), that is 45 cm wide and in which the plants are not over-crowded, should produce 15 to 20 kg, or 25 to 35 quarts of strawberries.

Prepared by Dr. A.R. Jamieson, Fruit Breeder
AFHRC
Agriculture and Agri-Food Canada
32 Main St.
Kentville, N.S. B4N 1J5
Canada