Millie Bull, Deputy Editor of Spare Time, has been growing strawberries on her south-facing balcony in Kent for three years. She reports that a single crucial task—feeding plants with tomato food—has transformed her harvest from a handful in year one to dozens of large, juicy berries in year three.
Why Tomato Food Works
Bull explains that tomato food is rich in potassium and phosphorus, which stimulate flower production and fruit development. She applies it every two to three weeks from early spring onward. “I saw dozens of white flowers appear in spring, which are now beginning to fruit,” she says, attributing the abundance to this feeding regimen.
Planting and Watering Essentials
Strawberries grow well in containers or grow bags. Bull uses a breathable fabric grow bag filled with multipurpose compost, planted in spring after the last frost. She waters thoroughly every morning, and during heatwaves, twice daily—once in the morning and once in the evening. “Strawberries in containers can dry out quickly,” she notes, emphasizing root-level watering to avoid grey mould on leaves and fruit.
Pruning for Maximum Yield
To focus energy on fruit production, Bull recommends removing runners as soon as they appear. “Allowing runners to grow diverts energy away from producing large, juicy berries,” she explains. Strawberries also need six to eight hours of direct sunlight daily; insufficient light reduces fruiting. Stressed plants from lack of water will also produce fewer flowers and smaller berries.
Feeding Frequency for Container Plants
While strawberries in mulched soil may not need regular feeding, container plants require fertiliser at least once a fortnight during the growing season. Bull prefers tomato food over general-purpose fertiliser for its high potassium content, which she credits for producing “huge” strawberries last year.
