Forcing Strawberries for an Earlier Crop

, written by gb flag

Just harvested strawberries

While I have nothing against preserves, the best fruit has to be ultra-fresh, eaten within minutes or even seconds of picking, while still warm from a sunny garden. And for me, strawberries are one of the most mouth-watering garden treats of all.

Careful choice of varieties can prolong your harvest, ensuring a trickle of fresh strawberries over a long period without having to resort to a bout of jam-making just to deal with a glut. If you just can't wait for that irresistible homegrown strawberry taste, for the very earliest harvest you'll need to force early varieties under cover.

Growing Strawberries Under Cover

Typically, strawberries forced under cover will begin fruiting two to four weeks earlier than those grown outside. If you have a heated greenhouse all the better. If not, don't despair – you can still enjoy great results by bringing strawberry plants into a cold greenhouse.

If you potted up some runners to replace tired old strawberry plants last year, select a few of these for forcing. If you didn't do that, leave plants where they are instead and cover them up with a row cover or cloche. One or two-year-old plants are best for forcing.

Strawberries in pots in the greenhouse

Late winter or early spring is the best time to bring strawberry plants under cover for forcing, as they'll have experienced a good cold snap and will be ready to burst into growth.

When you bring the pots indoors (or, if plants will be staying in the ground, before you cover them up), take the opportunity to treat your plants to a tidy up. Snip off the old, dead leaves, remove any runners that have formed, then give plants a top-dressing of fresh compost or well-rotted manure. Fresh, new, bright green leaves will quickly appear as the strawberries respond to the warmth of their protected environment and find spring coming earlier than they had expected.

Watch out for red spider mites, which like a warm, dry environment and will suck sap from your strawberry plants. Raising the humidity makes the environment less appealing for red spider mites, so keep potting soil moist and regularly damp down (splash the greenhouse floor with water). Aphids can also be a problem but are easily squashed by hand if you're not too squeamish.

Remember to provide ventilation on mild, sunny days to encourage airflow, which will help to prevent fungal problems.

Encouraging Forced Strawberries to Produce Early Fruit

Insect pollinators such as bumblebees may well visit your strawberry flowers but it's unwise to rely on them this early in the year. Instead, using a soft brush such as an artist's paintbrush, hand-pollinate your plants by gently tickling the inside of each flower once a day after they've fully opened.

Early flowers on strawberries

Once flowering starts, it's time to begin feeding; apply a liquid tomato fertilizer weekly. Plenty of sun and heat is instrumental in developing the intensity of flavour, so don't be too disappointed if these aren't the richest-flavoured strawberries you've ever grown.

James Wong recommends growing them through a mulch of red plastic film to reflect light back onto the plants and help produce bigger, tastier berries (incidentally, the same technique may also work for tomatoes).

Forced strawberry plants will be tired after the effort of starting so early (I'm the same in the mornings!) so shouldn't be used for forcing next year. The usual advice is to discard forced plants, but it would be a hard-hearted gardener who didn't give forced strawberries the chance to grow on and fruit again next year – after all, they will have served you so well at a time of year when fruit is scarce. If you do decide to keep them, you'll need to either repot your strawberries into a larger container or, if you have the room, replant them in the ground.

If you have enough space in your garden it's worth choosing an even spread of early, mid and late varieties, as well as setting aside some runners of your earlies for forcing. This way you'll have the longest possible season for fresh eating and will avoid having to deal with gluts. It would be a shame to get sick of something as delicious as strawberries!

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Show Comments


"My dad is 85 and a descendant of the oldest Strawberry Farmers on Cape Cod. He does not accet that runners make perfectly good New Strawberry Plants. He said they are the daughters, then daughters daughters, and with each generation the plants, runner plants, get smaller and are no good. He totally believes he must buy new plants every 2-3 years. How can i show him this is not true? I’ll try to print this article but maybe there is additional pieces of info i can show him. ? He is also totally old school, which i understand. But Back to Eden Gardening works! And makes so much sense. I’m PRAYING he watches the film that I’m going to order for him because we dont have much time to turn our family farm into a profit maker or the cousins will want it sold for the land. So a LOT is riding on this for me, as the one most excited and educated to turn farm into profiable farm, and for the entire family. Thank you!! "
CheriByGrace on Tuesday 9 January 2018
"Hi Cheri. Your dad is partially correct - after about three years, strawberry plants do tend to become less productive. I don't believe this has anything to do with the plants being propagated by runners however. It's just the natural productive lifespan of the plants. You don't need to buy new plants every few years - just propagate more from the runners. We have an article and accompanying video called 'How to Grow New Strawberry Plants from Runners' which has in-depth directions on how to do this (use the search box at the top of this page to find it). Good luck with your farm!"
Ann Marie Hendry on Friday 12 January 2018
"Hi Cheri, I read your query with both interest and puzzlement. Surely any strawberry plant of a named variety has come from runners? OK, nowadays we have tissue culture, but that is a relatively recent development. If he didn't use runners in the past, where did your father obtain replacement plants from? Any plants that he bought in would have come from runners that went back generations to the original plant. Growing from seed would give very variable results, which I'm sure wouldn't be suitable for someone growing their strawberries commercially, who would surely need reliable, consistent crops. Anyway, I hope that you resolve the problem, and are able to keep the farm up and running. It would be a pity to lose a part of the areas heritage. Best wishes"
Ian on Thursday 15 March 2018
"Love this article"
leona borge on Saturday 21 January 2023

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