If you’d to grow strawberries for a fresh, juicy crop a month or even six weeks before they’re ripe outside, try growing some in a polytunnel. While most strawberries are referred to as ‘June-bearers’ as that’s when they fruit, you can be eating them in May – or even April!
If the last few wet summers have made a dent in your anticipated strawberry crop, so that instead of harvesting nice ripe berries you find blobs of grey mould instead, it’s definitely time to think of a polytunnel or greenhouse. That way, you control the rain – and you get a seriously extended strawberry growing season.
Order the plants
For the very earliest strawberries
If your goal is to produce the earliest possible harvest, try ‘Mae’, available from Unwins. Considered to be the earliest fruiting variety on the market today, they’re very, very tasty, too. Plant them in September so that they establish a really good root system before things cool down too much, following the planting guide below. If you’re determined to push the envelope even further, plant them in the spring but don’t let them flower at all in their first year. By the following spring they’ll be really well developed and raring to go!
For an extended strawberry season
Strawberries grown under cover are far more reliable than outdoor fruits in a bad summer. If you want to grow strawberries for the longest possible time, you also need a mid- to late-season cropper. ‘Cambridge Favourite’, also available from Unwins, does well under a wide range of conditions and is an excellent choice for a maincrop.
And, to extend the crop…
Finally, if you have the space, put in some ‘day neutral’ plants. These are also known as ‘everbearers’ and although the taste and texture aren’t quite as good as regular strawberries, they’ll crop on and off until the frosts. Unwins ‘Finesse’ will fruit right through until early September. Flower stems on everbearer plants should be removed until early June, after which they can be left to develop fruit. Finesse produces very few runners, so more of the energy gets diverted into fruit production.
Preparing the ground
Strawberries prefer a well drained somewhat acidic soil but will tolerate the same pH level that many other vegetables thrive in. Just don’t add lime or wood ash. Add compost at least a couple of weeks before planting, and top-water it regularly to help incorporate it into the existing soil.
How to grow strawberries
It’s so easy to grow strawberries, and they’re just so delicious that even a few plants are well worth it. If you plant strawberries in autumn, you will get a crop the following year. If you have to plant in the spring, then it’s best to clip off the flower stems to divert energy to the root system, otherwise you risk exhausting the plant. If you remove the flowers you won’t get any berries that year, but the following year you’ll have loads – and they’ll start slightly earlier than on plants set out the previous autumn.
Strawberries have a ‘crown’, where the roots meet. They somehow remind me of a squid – a mass of tentacles, and a body. Ideally, create a small cone-shaped mound in the bed, the peak of which should be at ground level. Spread the roots around the cone, then fill it in so that the crown itself is neither buried, nor higher than the surrounding earth.
A mulch – straw is ideal – should be spread around each plant as it grows, but before fruit begins to develop. This will prevent excessive water loss in warmer weather – particularly important when growing in a polytunnel – and also stop the berries from coming into contact with the ground which may cause them to mould before becoming ripe enough to pick.
For the same reason, take care to only water around the plants rather than directly on them, and let them dry before picking any fruit. Otherwise you risk spreading mould spores.
Pollination is key
If the flowers don’t get pollinated, you don’t get fruit. Make sure pollinating insects such as bees and hover flies can get in to the polytunnel. A net across the door with a mesh of around 1.5cms will keep butterflies out, while allowing the good guys inside – and back out again.
While it’s tempting to pick the fruit as soon as it begins to turn red, the sugar content soars if they’re left to become…perfect. So, try to resist the temptation. The difference a day makes is well worth it – just make sure the plants are dry when you pick.
Propagating strawberries is so easy that you shouldn’t need to buy them more than once. They are perennials and should give a much bigger harvest in years two and three, after which the level drops.
However, strawberries put out runners – lots of runners – on which are tiny plants. In doing so, they divert energy away from the parent plant. So, in year three, allow one or two runners to develop on the best plants, but only let them bear a single plantlet on each runner. This should be rooted in a pot while still attached to the parent, and only separated when it’s able to grow on by itself. Then you can plant them in the autumn in a fresh bed.
Cut the rest of the runners off regularly, or you’ll have a very difficult task cleaning up the bed later in the year.
After the harvest
Once the crop is finished, cut the leaves down to around 5cms then gather and dispose of the cuttings. This helps reduce the level of mould, and any other diseases, in the following year. It also means you can pull back the mulch (which should be replaced annually) without damaging anything, allowing you to add some compost around the plants well before the next crop is due.
Strawberries should be eaten fresh, and preferably without refrigerating them. While they don’t store as fresh fruit, they can be processed into jam, dried, canned or frozen.
Here’s one to try: put some in a blender, add a little lemon juice (and sugar if needed) and…blend them to a sludge! Then freeze in ‘ice lolly’ moulds, complete with sticks. Kids will love them! You can also add banana, apple or any other fruit you like.
Here in Wales we’re hoping for a crop that puts those of last year (and the year before that!) in the shade. We’ll keep track of how things go and post the results on FIMP. So, if you’re interested in finding out more about a year in the life of a new strawberry crop in a polytunnel, why not follow us on Facebook?