How to grow strawberries
Delicious ripe strawberries
There can be few countries in the world where strawberries are not grown. They are tolerant of most soil types, undemanding of nutrients and survive weather conditions ranging from cool, moist Scotland to fiery Spain. With careful choice of variety and a greenhouse, fruit can be available for half the year. Bob Sherman, Garden Organic's resident fruit expert, explains how.
As in all gardening, time spent in preparation is seldom wasted. Before spade hits soil, however, certain choices need to be made:
- The site: Ideally protected from wind, and in full sun for most of the day. Sufficient water and good drainage are two key elements for success.
- The varieties: Two broad categories: summer-fruiting and perpetual. This latter is a slight misnomer in that plants do not actually fruit for twelve months of the year, but cropping is extended to provide small, regular supplies of late strawberries from August until frosty weather arrives.
- The source: Strawberries succumb readily to viruses and soil-borne diseases. It is therefore essential to buy certified plants from a reputable nursery. It is a false economy to accept nameless runners from a well-meaning friend.
Preparing for plants
You cannot choose your soil, but you can improve it. Over-enriched soils will tend to grow lush green leaves as opposed to luscious red fruits, so it pays to restrain your organic fervour.
Check the soil pH and amend, if necessary, to about 6.5. A soil manured the previous year gives an ideal start. Such a soil will need the addition of garden compost at 1 barrow to 4m2, plus 75g per m2 each of bone meal and seaweed meal. If your soil is particularly short of nutrients apply one barrow of well rotted manure per 12 m2 in addition.
Both heavy and light soils benefit from leafmould. Moreover, strawberries thrive in it. Work in a 5cm layer to the top 10cm of soil just prior to planting.
Strawberry plants are supplied as runners either 'cold-stored', available from April to August or 'open ground', available from October to April. The advantage of the former is that they are likely to be established and fruiting well by the following summer. Plants set out after August will supply a progressively smaller harvest in the first year according to how late you plant them. Since you will only coax three good years out of your plants it pays to plant in July or August if you can.
Newly-received runners should be planted as soon as possible - in pots, a waiting bed or their final position. Set out plants at a spacing of 35-45cm apart within rows and 75cm between rows, allowing wider spacing on richer soils. It is important not to leave roots exposed nor to bury the crowns (see illustration). Firm the soil gently round plants with your heel or knuckles.
Before cropping: In spring, as growth begins, clear away any dead leaves and start checking regularly for aphids and other pests in the crown and elsewhere. If plants remain stunted and fail to grow, remove them immediately to the bin or bonfire, as they are showing clear signs of virus.
Once fruits begin to form, mulch the crop with straw to keep moisture in the soil and soil off the fruit. Where strawberries are grown through polythene, straw is not needed.
During cropping: From June onwards your plants will begin to produce rapidly extending runners. These can be left and trained in to produce a matted row about 35 to 40cm wide, removing those that stray out of line. This will produce more fruit but of generally smaller size. It may also increase the likelihood of disease. Alternatively remove all runners regularly unless you need one or two to fill gaps in the rows.
After cropping: Once the last strawberry has been tumbled down the throat, clear up the bed by cutting back all foliage (leaving a stump of 10cm or so) and removing it, and any straw, to the compost heap. Take care not to cut so deeply into the plant that the crowns are damaged. If necessary, keep the soil irrigated to ensure plenty of fresh new growth which will gather energy far more efficiently than those tired old leaves would have done.
Growing through plastic
Strawberries grow well (and weed free) through a mulch of polythene or woven
polypropylene. Whilst the woven fabric allows water to percolate, polythene
does not and some form of seep or drip irrigation will be needed under it.
In general, where such soil covers are in use, on heavy soils it is beneficial to raise the beds by about 10cm to reduce waterlogging. Make single rows 60cm wide or, if woven soil cover is used, a bed sufficient to fit double rows 75cm apart.
No straw is needed on such systems but, otherwise, all normal husbandry practices apply.
A strawberry bed will not last longer than three years before fruits become
small and virus and disease stunt the crop. As a result a rotational system
will be needed. There are many possibilities, including alternating with another
crop such as rhubarb or attractant flowers or rotating them round the vegetable
garden. Ideally strawberries should not be regrown on land vacated by either
strawberries or raspberries for at least three years, preferably more.
In the intervening years, a top-dressing of leafmould or low nutrient soil improver in early spring should be adequate. On poor soils garden compost is preferable. If leaves grow strongly and are a deep green colour it is clear that too much nitrogen is present. Removal of leaves and mulching after cropping should continue as in the first year.
|Variety||Season||Cropping||Flavour||Pest & Disease Resistance|
|Cambridge Vigour||Early||Good for two years; replace after second year||Excellent||None|
|Elvira||Early||Good||Excellent||Resistant to mildew|
|Honeoye||Early||Good||Good||Susceptible to verticillium|
|Redgauntlet||Early||Often twice||Good||Resistant to botrytis|
|Tamella||Early/mid||Very Heavy||Good||Susceptible to crown rot|
|Cambridge Favourite||Mid||Good||Good||Resistant to mildew, verticillium and partially to botrytis. Susceptible to red spider mite|
|Elsanta||Mid||Heavy||Excellent||Susceptible to mildew and verticillium|
|Symphony||Late||Heavy||Excellent||Tolerates vine weevil; resistant to red core and possibly to crown rot and verticillium|
|Cambridge Late Pine||Mid/late||Moderate||Excellent||Susceptible to mildew|
|Pegasus||Late||Good||Good||Some resistance to botrytis, mildew and verticillium|
|Maxim||Late||Very heavy||Good||Resistant to drought|
|Rhapsody||Late||Good||Good||Resistant to red core, verticillium and mildew. Good for northern gardens|
|Aromel||Perpetual||Good, replace after one or two years||Excellent||Susceptible to mildew|
|Mara des Bois||Perpetual||Good||Excellent - wild strawberry flavour||Resistant to mildew|