Tomato in May: monthly care

Tomatoes need full sun and warmth to crop well, so choose the sunniest, most sheltered spot you have—ideally a south-facing wall or greenhouse. They thrive in loam soil enriched with plenty of well-rotted compost or manure dug in a few weeks before planting. Good drainage is essential, but the soil must also retain moisture during the growing season. In temperate Europe, sow seed indoors from March onwards at 18–21°C, or buy young plants in late spring. Plant out only after all risk of frost has passed—typically from mid-May in milder areas, early June in colder zones. Harden off plants for a week before transplanting. Space plants 50 cm apart in the ground or in large containers (at least 30 cm diameter) filled with multipurpose or tomato compost. Plant deeply, burying the stem up to the first true leaves; tomatoes will root along the buried stem, creating a stronger plant. For cordon (indeterminate) varieties, insert a sturdy 1.8 m cane or stake at planting time, positioning it a few centimetres from the stem to avoid root damage. Bush (determinate) types need less support but benefit from a short cane or cage to keep fruit off the soil. Water thoroughly immediately after planting to settle roots, then keep the soil consistently moist. Apply a 5 cm layer of organic mulch around the base to conserve moisture and suppress weeds, keeping it clear of the stem itself. In greenhouses, ensure good ventilation to prevent humidity building up around young plants.

Tomatoes have high water needs and consistent moisture is critical for healthy fruit development. Water deeply two to three times a week in dry weather, more often for container-grown plants, aiming to keep the soil evenly moist but not waterlogged. Irregular watering causes blossom end rot (black patches on fruit) and split skins. Water at the base of the plant, not overhead, to minimise fungal disease risk. Feed regularly from May through August once the first fruits begin to set. Use a high-potash liquid tomato fertiliser every 10–14 days, following the manufacturer's instructions. Potassium promotes flowering and fruiting; nitrogen-heavy feeds produce leafy growth at the expense of tomatoes. Container plants may need feeding weekly as nutrients leach out faster. Tomatoes are tender perennials grown as annuals in temperate Europe; they cannot survive frost and are hardy only to zone 10a–12b, far warmer than our climate. Outdoor plants will be killed by the first autumn frost, so harvest all remaining fruit in late September or early October. Green tomatoes can ripen indoors on a windowsill. Watch for blight (brown patches on leaves and fruit), especially in wet summers. Remove affected foliage immediately and avoid overhead watering. Whitefly and aphids can be problems under glass; use biological controls or insecticidal soap. Refresh mulch mid-season to maintain moisture levels and suppress weeds, and ensure greenhouse plants have good ventilation to prevent botrytis and other fungal issues in humid conditions.