Propagating strawberries: runners or seed?

Propagating strawberries on your own is a fun project and a great way to keep your garden stocked with fresh, healthy, and vigorous plants.

For optimal harvests, it is necessary to replace your strawberry plants from time to time, and to rotate your planting locations every three to four years. This helps avoid build-ups of pests and diseases. Instead of buying new plants, why not try your hand at propagating your own? Strawberries can be propagated by seed or by their runners. Propagating by strawberry runners will give you an exact replica of the cultivar of your existing plants. This is good if you have a variety that tastes great and produces abundant yields.

However, not all varieties produce runners. Also, if you have several different varieties of strawberries in your garden, there is a high likelihood that your strawberries are cross pollinated.

Therefore, if you try growing strawberries from seed, you could end up with a wonderful variety that has its own combination of taste and aesthetics. Find out here the best methods for growing strawberries from seed, and how to plant strawberry runners.

Propagating strawberry runners

Strawberry runners are modified stems called stolons, which are horizontal stems that create new plant clones at their nodes. Therefore, one of the easiest ways to propagate your strawberry plants is through the clones found on the runners.

Since you are cloning your existing plants, make sure you are propagating your best by marking or labelling the ones that have the best taste, or the most abundant yields.

Propagating strawberry runners is quite easy, as the plant will naturally grow adventitious roots from the nodes of the runners. Summer is the best time to propagate strawberry runners; however, make sure you have them well-rooted and planted by early autumn. This gives the plants enough time to establish themselves before winter.

Following the steps below will help you succeed in growing strawberries from runners.

• Select your runners from the healthiest, the best tasting, and/or the most prolific producers.
• Use a nutrient-rich and well-draining soil, like our Plantura Organic Tomato & Vegetable Compost. It contains sufficient nutrients to give your new plants the support they require.
• Gently dig up already-rooted runners, cut their connection from the main plant, and pot them in small containers, 10-15cm in diameter.
• If the runners haven’t rooted on their own yet, you can bury your small pots partially in the soil, fill them with media and lay the runners across them. Use tent stakes, or wire bent into a “U” shape to hold the nodes in place on the soil while they root.
• After they are sufficiently rooted, sever these new plants from the main plant.
• Your new plants can be planted in the ground throughout August. To avoid any damage from cold weather, make sure they are in the ground by early September.
• Protect your new plants from early autumn frosts by covering them with horticultural fleece. This is only necessary for the first few weeks once planted in the ground.

Growing strawberries from seed

Growing strawberries from seed, while rewarding, is more difficult than propagating from runners. Strawberries are the only fleshy fruit that wear their seeds on the outside. The flesh of the fruit that we eat is actually the receptacle, and therefore, strawberries aren’t true berries but accessory fruit. The seeds on the outside aren’t just seeds, but achenes, or simple dried fruit similar to a nut.

Many strawberry varieties are hybrids from which seedling offspring will not stay true to form. While these new plants may not turn out exactly like their parent plant, they can still be delicious varieties with a bountiful harvest. Alpine strawberries and many heirloom varieties do tend to reproduce true to form, so these may be the best choices to start with.

Seeds can be collected by rubbing the skin of dried fruit, or by peeling the outer layer off a fresh strawberry and drying it. You can also separate the seeds and the fruit in a blender. Simply place a few strawberries in the blender with a cup or two of water. Too much blending can damage the seeds, so just pulse the blender a few times to mash up the fruit. Let the mixture sit for a few minutes, and the healthy viable seeds will sink while the pulp and fruit bits will float. Skim off the pulp and pour out the water and seeds into a cup. Then pour out the water from the cup and spoon out the wet seeds onto a piece of paper to dry. Once dry, the seeds can be scraped off the paper and stored.

Strawberry seeds need to be stratified to germinate. This means they need a cold treatment. Wrap your dry seeds in tissue and place them in a sealed container in your freezer at -1 °C for 2 to 4 weeks. After this, pull the container out of the freezer and let them slowly come to room temperature. At this point, the seeds are ready to plant.

When growing strawberries from seed, it is recommended to have a loose, well-draining soil. This can be easily achieved by a 1:1 mixture of sand and good quality peat-free compost like our Plantura Organic Herb & Seedling Compost. With its loose structure and its low but adequate level of nutrients, proper root growth and seedling plant development are ensured.

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The following steps explain how to plant strawberry seeds.

• Use small pots or seed starting trays filled with a 1:1 mixture of sand and peat-free compost.
• Gently water your media until it is sufficiently and uniformly moist; allow excess water to drain.
• Sprinkle a few seeds per small pot, or 2 to 3 seeds per cell in the seed starting tray.
• Lightly dust the seeds with a very thin layer of your mixed potting media. Strawberry seeds are small and will germinate better if partially exposed to the light.
• For optimal germination, place in a bright room, or near a sunny window.
• Keep temperatures between 15 to 20 °C, and use a heat mat to gently keep the soil warm.
• Covering your pots or trays with a plastic bag, or with a clear cloche, will increase humidity so that the seeds do not dry out. Mist the soil with a spray bottle of clean water periodically.
• Once the seedlings are 3 to 5 cm tall, you can thin the seedlings by gently pricking out those that are too close together and leaving the largest and most vigorously growing ones.
• After your seedlings have 3 sets of leaves, you can gradually introduce them to direct sunlight and harden them off to cooler temperatures by bringing them outside for short periods.
• Transplant your new plants into your garden when temperatures are above 10 °C. If you are transplanting during the summer, plant them out no later than mid-July to ensure they are well settled and developed to survive the winter.

Find out more on how to care for and grow your strawberries in our in-depth articles on strawberries.