Summer Strawberries

Friday, June 18, 2010 by Jeremy Dore - Categories: gardening organic strawberry
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If I had to pick a fruit that benefits from home-growing more than any other it would be strawberries. The taste of fresh strawberries heralds the arrival of summer for many people but modern methods of mass-cultivation often leave shop-bought varieties tasting bland or mushy. Contrast this with the soft fragrant strawberries picked from your own garden and the supermarket offerings seem very poor in comparison. For the best tasting perfectly ripe strawberries there is only one option: grow them yourself.

Although strawberries can be grown from seed this rarely works well. It is important to start with virus-free plants from a garden centre or nursery because viruses are easily transmitted from infected plants. Strawberries are traditionally planted in autumn so they have time to establish a good root system necessary to yield a crop the following year. Increasingly popular are ‘cold-stored runners’ which can be planted during spring and early summer. These will produce a modest first crop the same year and then a full crop the following year.

Strawberry Check-List

Although strawberries are quite easy to grow they don't always reward you with the best crop unless their specific preferences are taken into consideration:

• Soil: Strawberries always benefit from a rich fertile soil with plenty of compost and organic matter dug in. The better the preparation the better the harvest.
• Competition: Keeping strawberries weed-free is vital and, although the 50cm (20") minimum spacing recommended by our Garden Planner may seem excessive, the resulting crop will be much better for the extra room.
• Water: Strawberries need a combination of well-drained but moisture-retentive soil. Raised beds with plenty of organic matter such as compost and leaf mould are ideal and it is particularly important to keep plants well watered during the fruiting period. Although garden centres will often showcase elaborate tiered strawberry pots and hanging baskets these can be difficult to water evenly so be aware that they are often more ornamental than productive.
• Sunlight: Although originally a woodland plant that will tolerate shade, strawberries give the best crop when given plenty of sunlight.
• Air Circulation: Strawberries are susceptible to a number of moulds, particularly in overcast damp weather, so always ensure good ventilation if grown in a greenhouse or under cloches.

Once fruit start to swell it is necessary to lift them from the ground to prevent the berries from getting damp and mouldy. Two methods are commonly used here: adding straw to lift them off the ground or growing through black membrane. If using straw, don’t add it too early in the season as it can harbour slugs and insulate the plants from the warmth of the soil causing late frost damage. Black membrane is cleaner and prevents runners rooting but requires careful watering of the plants at their bases (never on the leaves which can encourage virus spread).

Most commercial growing is done in plastic-covered beds (which keep the soil warm and the fruit clean) or in raised containers (to keep slugs off). Grow-bags raised off the ground can provide a similar convenience for the gardener but remember that they will need careful watering to keep an even moisture level in the soil. In a greenhouse hot dry conditions can lead to red spider mite problems.

Keeping Pests Away

There are a number of potential pests when growing strawberries but the big two are:

1. Birds: It is almost always necessary to net plants to prevent birds picking them off or you will quickly find partly-ripe fruit lying around the plant with tell-tale peck marks in them as I did earlier this month. Choose netting with 2cm (3/4") holes rather than garden fleece so that beneficial insects can still pollinate the flowers and keep down pests.
2. Slugs: The usual variety of methods including beer traps and picking them off by hand at dusk must be used to prevent slugs beating you to your harvest.

Strawberry plants rapidly lose vigour after three years of harvest and need to be replaced. This can either be done using fresh disease-free stock from garden suppliers or by propagating your own plants from the runners each strawberry plant sends out in summer as described in our Strawberry Runner GrowBlog article. However, producing runners does take strength from the plant so make sure that excess runners are removed from the plant so that it can channel most of its energy into producing fruit.

Although it is possible to replace all your strawberries every three years a better approach is to replace just one third of them, rotating them to newly enriched and prepared soil as this also reduces the possibility of soil-borne pests building up.

The Fruit of Your Labour

I have tried a few varieties over the years and generally prefer the standard summer fruiting types that give good crops of large berries. I always choose taste as the main criteria as some hybrids lack the intense taste of the best strawberries. Alpine strawberries yield smaller, often elongated fruit which have a fine flavour but the trade-off is less harvest. Some alpines don’t produce runners and although I have some in my garden I probably won’t replace them when those ones are spent. Likewise perpetual varieties which fruit through to autumn are good if you have room for them as they extend the season but rarely produce as much harvest.

There’s no getting away from it: strawberries don’t keep well. Yes, you can freeze them to use in preserves, deserts or smoothies but this is probably best reserved for blemished fruit or a sudden excess. In my family the strawberries never get that far, rarely even reaching the table as they are so delicious when freshly picked, rinsed and eaten. The seasonality of strawberries may mean that we only get them for a few summer months but the mouth-watering taste is easily worth all the effort!