Best Strawberry Growing Tips and Advice
I am very fond of, but I feel very concerned by the fact that a whole generation has grown up not really appreciating how a properly flavoured strawberry can taste. They have sampled mass-market, commercially grown and often imported fruits that bear little relation to the garden strawberries that I knew as I child, and indeed still cultivate. A good strawberry is not difficult to grow; it is largely a matter of choosing the right variety, but it has to be said that the best flavoured varieties tend to be the shortest-lived and it is a serious mistake to think of any strawberry in the same, long term way as raspberries and currants. Think of them, in gardening terms, more as vegetables and you will be able to organize your strawberry growing to best effect.
HISTORY AND TYPES OF STRAWBERRY
As with other fruits, the taste of wild strawberries was first appreciated a very long time ago, but it was to be many centuries before they were first cultivated. The Greeks and Romans ate strawberries and there is evidence for them having been collected even earlier, in prehistoric times. The wild, so-called wood strawberry, Fragaria vesca, is a fairly common species of woodland edges throughout Europe and occurs also in the eastern part of North America. The name strawberry, doesn’t incidentally, seem to have anything to do with the practice of putting straw around the plants and long pre-dates their cultivation. It probably comes from ‘strayberry’, for thecause young plants to stray from the parent.
Strawberries were probably first grown in gardens in the thirteenth or fourteenth centuries but for many years afterwards, especially in England, they differed little from the wild plants. There are other types of wild European strawberry: the small-fruited Alpine strawberry, a form of Fragaria vesca, is especially valuable as it has a much longer fruiting season; but the large-fruited summer garden strawberry we know today, owes its origin mainly to crosses made between two American species, the Virginian Fragaria virginiana and the Chilean Fragaria chiloensis. In turn, crosses between them and Fragaria vesca gave rise to the so-called ‘ever-bearing’ or ‘remontant’ strawberries which crop in summer and again in the autumn. A huge range of large-fruited, summer-cropping varieties now exists but the appeal of the longer fruiting period of remontant strawberries has recently led to a number of new and improved varieties of this type.
A quite different type of strawberry, with a longer cropping season, is the Californian day-neutral. Here, unlike the traditional European strawberries, flowering and fruiting are not dependent on day-length, and a number of day-neutral varieties are now appearing in Europe. Planted outdoors in northern Europe, they behave pretty much like remontant strawberries but in warm climates or in, they fruit virtually continuously. Their drawbacks are that they can really only be grown as annuals because the second year crop is very small and, by general consent, the flavour is not as good as that of the more familiar European varieties.
STRAWBERRIES FROM SEED
For many years, it’s been possible to raise some of the small-fruited alpine strawberries such as ‘Baron Solemacher’ and ‘Alexandria’ from seed, but in recent seasons, a few day-neutral varieties have been introduced to European gardeners in seed form, too. The first was ‘Sweetheart’ but others, such as ‘Temptation’, have followed and no doubt many more will too. They are easy enough to grow. The seed is sown in the same way as for normal hardy annuals but the flavour will never be as good as that of the traditional large-fruited varieties.
The bestfor strawberries is moisture-retentive, humus-rich and slightly on the acid side of neutral. In effect, this is the soil of a good and this further underlines the sense in thinking of strawberries more as a vegetable crop and less as a fruit. Heavy clay soils that have been improved with manure or compost are good for strawberries, but a very light, free-draining sand will need constant work and regular addition of organic matter if really worthwhile crops are to be obtained.
Strawberries must have sun, and the ideal site would be a very slightly sloping bed facing south. You will be unlikely to produce a satisfactory crop from a site that is shaded for longer than a small part of the day, and in such circumstances, I would strongly advise you to grow instead some perennial, small-fruited Alpine varieties such as ‘Baron Solemacher’, which can even be grown as edging at the front of a herbaceous border. For the more traditional varieties that crop over two or three years, do take care to dig out any perennial weeds (couch grass especially) before planting as you will damage your plants by trying to do so later. Strawberries will tolerate a windy position but if the winds are very cold, you must expect some leaf browning.
Bearing in mind my suggestion to think of strawberries in much the same way as you would vegetables, you will realize that they need to be rotated; that is, each batch of plants should be grown on a different area of soil. This ensures that all of the nutrients in the soil are used to the full and, most importantly, that any soil diseases and pests have the opportunity to die away. Allowing at least four years before returning to the same plot is ideal. There are two ways to approach this.
The simpler option is to grow your strawberries as an annual/biennial crop: plant them in the summer of one year to crop through the next and then dispose of them. If you choose this system, you should select varieties that really respond best to this approach and offer little in the second year: the old types such as ‘Cambridge Sovereign’ or, at the other extreme, the modern American day – neutral varieties. Next decide on the area that you are prepared to devote to strawberries (taking into account the yields you may expect) and divide it into four equal plots.
If you decide that you don’t want to go to the trouble and expense of replanting every year, you must choose varieties that will crop for more than one season. This scheme is based on keeping the plants for three fruiting seasons before disposing of them.
Whichever system you decide on, however, I would urge you not to try and grow a mixture of annual/biennial and longer-term plants because the planting and cropping scheme will then become hopelessly complicated.
Some protection from birds is highly desirable and the simplest way to achieve this is with lightweight fruit netting supported over the bed on short canes with upturned plant pots on top. A neater method is with a purpose-made strawberry net, supported on a light frame.
Strawberry plants are available from spring through to autumn but, in general, the earlier they are planted, the better they will establish ready for cropping in the following year. They are sold in various ways.
Freshly dug runners
Either loosely packed in plastic bags or properly potted-up, usually sold in late autumn and early spring, depending on the severity of the weather.
Cold stored runners
Dug in winter, with their leaves trimmed off and then stored in the cold to be taken out for sale from spring to late summer. They won’t establish well if planted later than this.
Potted-up cold stored runners
These offer the most versatile option as they have been potted-up by the nursery and grown on in a greenhouse for planting from midsummer until autumn. They will cost more than bare-rooted runners but are much more dependable.
My experience has been that all pot-grown plants establish best if they are in bio-degradable pots which are then planted entire, allowing you to avoid the root disturbance that strawberries resent. The best nurseries will always pot-up routinely in this way.
About one week before planting, scatter Growmore or, blood and bone over the bed at 68g per square metre (2oz per square yard) and rake it into the surface. Plant pot-grown or bare-rooted runners with a trowel and firm them in very thoroughly, ensuring that the roots are all covered and that the crown is on the soil surface, not protruding. Water thoroughly after planting.
There is a good deal of nonsense talked about the need to remove thefrom strawberries in the first year. I only find this necessary or worthwhile if they have been planted as bare-rooted cold stored runners. Pot-grown plants, put into a well-manured and fertilized soil will be perfectly strong enough to crop as they soon as they are ready.
There is very often an inevitable disparity in gardens between the ideal spacing and what is practical. The ideal is about 1m (3ft) between rows and 45cm (18in) between plants, but once the space demands of rotation have been taken into account, this can mean that a very large part of youris given over to strawberries, and 70-75cm (27-30in) between rows and 30-40cm (12-18in) between plants may be as much as you can manage. This will, of course, mean that you must take extra care when walking between the plants to pick the fruit.
GROWING STRAWBERRIES WITH PLASTIC MULCH
Duty forces me to discuss this technique, although I hate covering the garden with plastic sheet. The principle is that used by many commercial growers: fairly heavy gauge black plastic sheet is laid over the soil before planting. It’s essential to use black plastic as weeds will grow beneath a clear or translucent sheet. Either lay the sheet over the entire bed (and be prepared to walk carefully between the rows afterwards) or lay strips along each row, anchoring them at either side by burying the edges.
Make slits in the plastic through which you can plant. The advantages are fairly obvious: weeds are controlled, soil moisture is retained, and the fruit are protected from contact with the soil. The disadvantage is that your strawberry bed will lose any pretence at being attractive and become purely functional. You will also have a great deal of dirty, waste plastic sheet to dispose of each time you move the bed; not an appealing notion in a green, recycling age.
Apart from feeding and watering, strawberries need a modest amount of additional care. It’s important to keep the fruit out of contact with the soil, otherwise they will fall prey to woodlice, mould and other problems. Although one way to avoid this is by growing the plants through a plastic mulch, a much more attractive method is the traditional one of laying straw beneath the plants as the fruit begin to swell. Tuck it beneath the plants so that it isn’t blown around in the wind. Bracken is an acceptable alternative if it’s available locally and it is now possible to buy proprietary strawberry mats, too. Don’t, however, make the mistake of applying the soil cover too early for it will insulate the soil, trapping warmth within and making the plants vulnerable to frost damage on cold nights.
Immediately after the fruit have been picked, the old foliage should be cut off. This is most easily done with shears (I find single-handed shears the most convenient), and the plants should be trimmed to within a few centimetres of the crown where the new leaves will already be unfolding. The old straw from between the plants should be cleared away at the same time.
Perhaps the biggest confusion that gardeners have about strawberries comes in dealing with the runners —the stems that run along the soil surface, producing baby plants at intervals along their length. These will begin to form in early summer and if the plants are grown in a limited area at close spacings, the runners should be cut off as they grow. This allows each plant to concentrate its energies into developing the single crown. Where space is not limited, however, and the plants are wide apart, then you should retain about eight or ten runners from each plant and cut off the remainder. Allow them to root in the spaces between the plants, ideally arranging them so they are uniformly spread. You shouldn’t, however, pot-up or transplant the runners to increase or renew your stock. They will not be reliably free from disease and, as always with soft fruit, it is much the best idea to begin with fresh certified virus-free plants.
FEEDING AND WATERING
Apart from the pre-planting fertilizer, strawberries should be fed in early spring with a light dressing of about 17g per square metre (1/2 oz per square yard) of potassium sulphate. If the plants have not cropped well, this should be repeated when the foliage is cut back after picking, but otherwise this second application is unnecessary. Watering is very important and in most years, additional water should be given regularly from the time that the fruit begin to swell until they have been picked. Watering earlier in the season than this will merely encourage leafy growth.
I have already pointed out the importance of clearing perennial weeds from the plot before planting and, thereafter, annual weeds should be controlled by hand. In a small, garden-sized strawberry bed, this is perfectly feasible and the hand fork should be the preferred method, as hoeing can easily damage the roots.
YIELDS AND QUANTITIES OF PLANTS NEEDED
From what I have said already, it will be apparent that is not easy to generalize about the yield of strawberries because it is tied closely to the varieties grown, the type of planting stock, the time that they are planted, the spacing adopted and the number of years over which they are cropped. My experience, however, is that a high-yielding commercial variety, such as ‘Cambridge Favourite’, the most popular in Britain, planted early as pot-plants should produce about 450g (I lb) of fruit per plant in its first cropping year if grown as single-spaced plants with the runners removed. Most families’ needs, should be satisfied by 25-35 plants.
EXTENDING THE STRAWBERRY SEASON
Uniquely among commonly grown soft fruit, the season for strawberries can be extended, even without a greenhouse, because the plants are small enough to be covered with cloches. Glass cloches put over the plants about two months after midwinter will advance the first ripening by up to a month. Plastic cloches will give about two weeks advance. When using cloches of any type, however, it’s important to provide some ventilation or botrytis grey mould will become a problem.
If you enjoy fresh strawberries and have a greenhouse, you can produce fruit for about eight months of the year.
HARVESTING AND STORING
Strawberries for immediate use or to be used for freezing or jam making should be picked when the fruit are uniformly red; they will only keep fresh for a couple of days in this condition. Unless they are to be used within a few hours, they should be picked complete with the calyx. The storage time can be extended by picking partly ripe fruit which will keep for up to a week or more in a refrigerator, but will never be as sweet and tasty. It is because commercial crops are usually picked this way that strawberries bought at a supermarket are rarely as sweet as those which are freshly picked from your own garden.
Although varieties do differ slightly, no strawberry will ever emerge from a freezer with exactly the same shape, texture or flavour as when they were fresh, and for this reason, if you choose to freeze the fruit, then they are best re-used for cooking purposes.
PROBLEMS AFFECTING STRAWBERRY PLANTS
Like any vegetatively propagated crop, strawberries are prone to virus diseases but these are generally not very serious because the plants are grown for such a relatively short time. The succulent fruit are as attractive to pests and moulds, however, as they are to us.