What if you could multiply your strawberry crop for free? Well, you can! Sow seeds, divide plants or – my favourite – propagate them from runners, and you’ll be able to keep your strawberries going on and on, season after season, far into the future. Sweet, juicy strawberries – for life! Here’s how to do it.
Growing Strawberries From Seed
Strawberry seeds form on the outside of the berry. It’s a really fun project to save these seeds and then grow them yourself but it does take a little bit of time, and because more strawberries are modern hybrids, there’s a very high chance that the seedlings you get won’t taste anything like their parents. A better option is to buy a packet of strawberry seeds, which isn’t quite free but, with more seeds than you’ll ever need in each pack, it is a very cheap way to start growing lots of strawberries.
Strawberries are best sown in spring. Scatter the seeds into small pots of already-moistened potting mix, then very lightly cover with a little more of the mix. Cover the pot with clear plastic to keep humidity high, then germinate your seeds at room temperature (about 68-70ºF or 20-21ºC).
Once the seedlings have grown to 2-3 inches (5-7cm) tall, carefully separate them and transfer into individual pots. Grow them on in a bright position but out of direct sunshine, then gradually acclimatize to the outdoors before setting them out about a foot (30cm) apart. They can also go into containers at a slightly closer spacing.
Strawberries can also be propagated by division. The crown of the plant can naturally split, producing multiple crowns which can be carefully pulled apart and potted up to grow on and then replant.
However I’m not a big fan of division because you’ve got to dig up the plant, which causes them stress, and you can sometimes damage the divisions when doing this. It just makes little sense when you can just as easily grow new strawberries from their runners.
Propagating Strawberries From Runners
If you’re growing your own strawberries you’ll probably be familiar with these long, wiry stems racing out from your plants. They’re called ‘runners’ and it’s the most efficient way that strawberries reproduce themselves. Botanically speaking these are stolons – creeping horizontal stems that produce leaves and roots at intervals along their length to form new plants – and we can use this naturally occurring habit to grow new plants. Growing new plants from runners is pretty much bulletproof – it’s hard to go wrong! When you grow new strawberries this way you’ll get identical plants, because they share the same genetics.
Runners coming from newly-planted strawberries are best removed before they root, as they take a lot of energy to produce and the plant needs to concentrate on establishing itself first. From their second year you can begin to root the runners. Only propagate from healthy plants so you’re not passing on any diseases or viruses to the new plants.
If you want to bulk out an existing strawberry bed, just root the runners right there where they are, directly into the soil. You can direct the runner to where you want it to be – they’re nice and flexible like that! If you’re starting a new strawberry bed elsewhere, root your runners into small pots so when you detach them from the mother plant you can easily transplant them. Fill your pots with an all-purpose potting mix, firm down, then water to thoroughly wet the mix.
Wherever you see a small cluster of leaves along the stem, this is called a ‘node’, and this is where the runner wants to send out new roots from. You may see the very beginnings of roots already, or you may not. To make the plantlet root into your pot or where you want it to be in the soil, you need to pin it down. You can use a hairpin or even just weight the stem with a small rock. Another option is to make your own staples by cutting short lengths of thick-gauge wire and bending them into a U shape. Pin down the runner close to the node with your staple. Make sure the base of the node is pushed down firmly into the potting mix or soil so it knows to start pushing out those roots. Push in the staple to hold it in place.
If the runner has already rooted into the soil, no problem – just carefully dig it up with a hand fork and then replant into your prepared pot.
Older, longer runners may have more than one node along their length, and you can use each of these to create a new plant. However, if you have plenty of runners to choose from, it’s best to focus on growing just one node per runner. This concentrates all the energy from the mother plant into producing just one strong new plant. Pin down the node closest to the mother plant and cut off the growth beyond where you’ve pinned it down. Make sure to keep the new plant well-watered.
In general, if you’re not propagating any more strawberries, it’s best to remove any runners that have formed. That way the plant will have more energy to produce plenty of flowers and, of course, berries.
Turn Your Strawberry Runners Into Strawberry Plants
Think of the stem leading to your pinned-down node as an umbilical cord. It’s the lifeline for the baby plant, so you want to leave it attached to the mother plant for as long as possible. Only cut off the runner once the plantlet has properly rooted into the potting mix. It should take about three to four weeks to root, and you can detach it from this point, or leave it a few weeks longer just to be on the safe side. Remove it too early and the young plant may not be strong enough to fend for itself, and could simply shrivel up. I like to see the roots in the drainage holes of the pot before I plant it elsewhere.
Choose a sunny position in well-drained, fertile soil for your new plants, or plant into suitable containers. Begin feeding with a liquid tomato feed when they start to flower, usually next spring.
If you’ve rooted runners near the end of summer and you live in a colder climate, it may be safer to overwinter your strawberry seedlings in a greenhouse or cold frame before planting out next spring.
Strawberry plants usually become less productive after three or four years, so by replacing plants with runners you’ll always have vigorous, ready-to-fruit plants.