Life & Style
Strawberries are one of the easiest fruit crops to grow – and they're irresistible to tiny green thumbs.
Plant them now and you'll enjoy a summer-long harvest of juicy berries. But before you start licking your chops in anticipation, there are a few simple tricks you can do now to ensure bigger, better, juicier, tastier berries this season.
Strawberries will grow in most sunny situations (the more sun while the fruit is ripening, the sweeter the fruit) but they don't like wet feet. Sort out any drainage issues you have before you plant to prevent root diseases further down the track. If your soil is prone to waterlogging, plant on ridges, in raised beds or in containers.
Having said that, the soil should be moist (just not waterlogged), so dig in plenty of compost before planting then fork in chicken manure, if you've got it, between the rows. As the manure rots down it will provide additional fertiliser as the strawberry roots spread out.
Strawberries are susceptible to the same soil-borne diseases as tomatoes, potatoes and capsicums, so plant them in a different spot to where you planted your toms and spuds last year.
In an ideal world you would practise crop rotation and avoid planting your strawberries in the same spot for four years. Many commercial growers get around this by sterilising their soil with a yearly fumigation, although that's not an option for home gardeners.
If planting in pots, use a good quality potting mix with slow-release fertilisers. A commercial strawberry mix is available, which is ideal for pots. Hanging baskets also provide a good home for strawberries – just make sure they are watered frequently in the warmer months.
About six plants per person will provide bountiful berries for the dessert bowl come spring or summer. Keep the crowns just above soil level and space plants about 30-40cm apart to allow good air circulation. Don't bury the crowns (the centre of the plant from where new leaf growth sprouts) or your plants may rot.
Apply a general garden fertiliser and water in well.
Then cover your soil with mulch such as bark or straw, or black polythene. Mulch is magic. It suppresses weeds, keeps your soil warm, conserves moisture during dry spells and keeps the fruit from touching the soil, which encourages rot. And if your strawberries begin to rot (even the slightest decay to plant cells), slaters will move in. You can also use newspaper and pile mulch on top of this.
The only setback with organic mulch is that it, in itself, can attract slaters, which love to munch on decaying organic material. If dew or raindrops are constantly present on strawberries, slaters may migrate from your mulch to the wet berries that are lying on top. That's why many gardens like to plant their strawberries in narrow, rectangular containers where the berries can hang over the sides and dry out more quickly. This also helps to reduce slug and snail damage.
However, if you're growing yours in the garden and slaters are a problem, try lifting the ripening fruit off the ground. Use metal pegs that have a U-shape. Place them in the ground and lift the berry so it rests on top. Once picked, move the peg to another ripening berry.
Feeding and watering
Berry production requires good soil nutrition, so adding a balanced fertiliser to your soil before planting is ideal. A slow-release fertiliser is also beneficial. Thereafter, I give my strawberries the occasional feed of liquid seaweed fertiliser. In any case, in late winter/early spring apply a fertiliser that has roughly the same potassium (K) ratio as nitrogen (N) – a liquid tomato fertiliser is ideal. Feed again when you see fruit forming.
Don't forget to water, either. Regular watering is essential, particularly during fruit development. Water stress may result in small or misshapen fruit. This is often seen in greenhouses where temperatures can become extreme, causing rapid water loss due to transpiration. High temperatures and lack of water will halt normal growth. When a sudden bout of water is then applied, fruit put on rapid growth, resulting in peculiar shapes. If you're growing in a greenhouse, make sure there is plenty of daytime ventilation and that watering is regular.
Pests and diseases
Unfortunately you won't be the only one waiting for your berries to ripen. Birds will move straight in once the berries begin to blush red. When fruit is starting to ripen, cover your entire patch with bird netting to keep them out. Or you can make yourself a berry house that not only protects your berries but provides ornamental value to your garden too (I have step-by-step instructions for making a simple strawberry house on my blog flamingpetal.co.nz/category/diy).
Slugs and snails can be a problem and are best dealt with by using bait, or nightly patrols to pick them off.
If aphids are a nuisance (usually only so with older, unhealthy plants), wash them off with soapy water or use a pyrethrum-based insecticide.
If your strawberry plants are sporting a white, bubbly, foam-like substance, then you've got spittlebug. Spittlebugs feed on the stems of plants, sucking out the juices and causing stunted plants and small fruit. The leaves may also distort.
The best method of control is to crush and remove the spittlebugs with your fingers. In autumn, make sure you remove any dead plant stems, leaves and nearby weeds, as spittlebugs lay eggs late in the season to overwinter.
Grey mould (botrytis) is one of the main diseases of strawberries. It's worse during periods of rainy weather and high humidity as prolonged leaf wetness promotes spore production and germination. There are fungal sprays available, but the removal of infected fruit as soon as you see symptoms will help. Your first clue that you have it is the presence of small lesions on green and ripening fruit. If left on the plant, the entire fruit will mummify, then, when disturbed, large numbers of grey spores will be released in a mighty puff to infect your plants further.
Rejuvenating your plants
Strawberry plants should really be replaced every three years. They'll keep growing normally, but as the crowns grow older, plant vigour deteriorates, no matter how well you look after them. To keep up a constant, healthy supply of plants, take cuttings every year from about one-third of your plants (just lift up the runners and snip off any sections that have already rooted), discarding one-third of your oldest plants. Next year, take cuttings from another third of your plants and discard a third of your oldest plants. Do this every year and you'll continuously replenish your plants with good, healthy ones.
- © Fairfax NZ News