Agriculture, Aquaculture and Fisheries

Government of New Brunswick

Strawberries: Home Garden Cultural Guide

The strawberry, considered by many people to be a 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, runner development stops and flowers begin to form (initiation) for the next summer's crop. Temperatures above 180C favour 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 and gravelly soils need more nutrients and water to support a strawberry crop. 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.

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, improve it prior to planting by applying a generous amount of weed-free animal manure, peat moss, or compost. A green manure crop such as buckwheat, grown and incorporated in the soil the year prior to planting, is an excellent method of soil improvement. The New Brunswick Department of Agriculture soil laboratory will analyze soil samples and advise on limestone and fertilizer requirements.

USE OF LIMESTONE
Strawberries are best suited to soils ranging in pH from 5.8 to 6.2. Soils having a pH range of 4.0 to 5.0 are too acid 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.

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

Veestar: Early. Fruit is medium size, medium red, bright, medium firm, good flavour, a good fresh dessert variety, suitable for freezing.

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.

Cavendish: Midseason. Fruit is very large, bright medium red, medium firm, good flavour, resistant to red stele.

Glooscap: Midseason. Fruit is medium size to large, medium to dark red, firm, with good flavour and appearance. Produces large yields of berries, suitable for fresh dessert and freezing. Exceptional winter hardiness.

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

Blomidon: Midseason to late. Fruit is large, maintains size well through season, light to medium red, medium firm, good flavour, picks easily, excellent for fresh fruit.

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.

PLANTING SYSTEMS
There are many planting systems. The one best suited to New Brunswick is the matted row. Space the rows 1 m apart and the plants in the row 60 cm apart. Encourage the runners from these plants to root until the desired number of plants develop.

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 4.50C. 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. This system will offer protection to the plants for a maximum of one week.

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.

PLANTING

Set plants so that the midpoint of the crown is level with the soil surface (Fig. 1) and the roots are straight down and somewhat spread (middle plant in figure). If the plant is set too deep (on right), runnering will be delayed and the growing point of the crown may rot. If set too shallow (on left), the crown and the tops of the roots will dry out.

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 fertilizing, cultivation and weed control to encourage development of strong plants and early runners. Watering may be particularly beneficial during the establishment phase.

Figure 1: Depth of planting.

APPLICATION OF FERTILIZER
Apply a commercial fertilizer 4-6 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-M) at a rate of 50 g per 6 m row in mid August will improve the formation of flower buds. Remember to brush fertilizer off the foliage immediately after it is applied, to prevent injury.

CULTIVATION

Frequent cultivation of the planting is needed to control weeds and to keep the soil loose enough for the runners to root (Figure 2). 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 the plants or pulling it away from the crowns of the plants.

Figure 2: Hoeing

WEED CONTROL
Cultivation and hand hoeing are the usual methods of weed control. 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, food and light. Also, pollination may be poor in crowded rows.

Maintain a spacing of 10 to 15 cm betwee n runner plants. Remove all surplus runners after the desired spacing has been reached. 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 in early October.

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 will be subject to frost damage on blossoms and young leaves.

Oat and rye straw are ideal for mulch (Figure 3). 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.

Figure 3: Application of a mulch

Time of coverage is important!

It is recommended that you apply the mulch after the first hard freeze. A light frost will not hurt the plants, but they should be protected from temperatures of -9C. 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. A hard freeze may occur by November 15; in other years, it may not occur until December.

Early spreading of mulch, before the plants have become fully dormant, may cause severe damage to leaves and crown. In most of New Brunswick, November 15 seems to be a good date to apply the mulch. 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. 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 to protect the plants if frost conditions threaten.

RENOVATION

Figure 4: Blossom clipped by the strawberry clipper weevil.

Strawberry plantings can be maintained for several years. 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. Narrow the rows to 30 cm and then thin plants within the row leaving a space of 10-15 cm between plants. This is a good time to remove any weeds in the rows. Apply a mixed fertilizer to the rows, such as 1010-10 at 300 g per 6 m row. Remember to brush fertilizer off the foliage immediately after it is applied, to prevent injury. 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 (Figure 4), 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.

YIELD
A 6 m row of vigourous plants, that is 45 cm wide and in which the plants are not over-crowded, should produce 15 to 20 kg of strawberries.

EVERBEARING VARIETIES
All of the strawberry varieties described above are shortday plants, commonly known as June-bearers. These varieties initiate flower-bud formation in late summer when day-length is short. Recently, improved types of everbearing strawberries have become available. These everbearing 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 New Brunswick, fruit production (first year) is concentrated from mid-August until late September.

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 (or a spacing that will match the other rows of your garden) and the plants in the row 15 cm apart. Apply a 2.5 cm straw mulch to control weeds, conserve water, and to keep the berries clean. Remove flowers for 6 weeks after planting to promote plant establishment. As runner plants form cut them off with scissors. Fruit production will soon follow. 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 dayneutrals is preferable. Fruit will be produced from August to late September. 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. 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.

REFERENCES

Craig, D.L. 1982."Strawberry Home Garden Cultural Guide".Atlantic Provinces Advisory Committee on Berry Crops, Pub. 1000. Kentville, NS. 4 pp.
Craig, D.L. 1984. "Strawberry Culture in Eastern Canada".Agriculture Canada Pub.1585, Ottawa. 41 pp.
Jamieson, A.R. 1987."Strawberry Home Garden Cultural Guide".Atlantic Provinces Advisory Committee on Berry Crops, Pub.1000. Kentville, NS. 4 pp.
Jamieson, A.R. 1990."Cavendish Strawberry". Kentville Research Station Informatin Release No.13. Agriculture Canada. Kentville, NS. I p.