General
Tomatoes are warm-season annuals grown in Sweden mainly under glass or in sheltered outdoor spots. There are two main habits: determinate (bush) types stop growing after a set number of trusses, stay compact (about 60–120 cm), and suit pots and small spaces; they need little pruning. Indeterminate (tall) types continue to grow and fruit over a long season (up to 2–3 m with support), often giving higher total yields but requiring regular pruning and staking. Outdoors, reliable harvests occur mainly in mild areas (roughly zones 1–3), while greenhouses or warm walls extend success through much of the country. Aim for steady warmth, strong light, and consistent moisture to prevent disorders like blossom end rot and fruit cracking.
Light
Full sun (at least 8 hours of direct light; warmer, sheltered microclimate preferred outdoors).
Soil type
Deep, fertile, well-drained loam enriched with plenty of mature compost; good structure with high organic matter. Avoid waterlogging.
Water requirement
Even, regular moisture; 20–30 mm per week, more during hot spells. Water the soil, not the leaves.
Nutrient requirement
High. Pre-enrich soil with compost, then feed with organic tomato fertilizer rich in potassium once flowering begins; moderate nitrogen early, low nitrogen later. Ensure adequate calcium and magnesium.
Precultivation
Sow indoors 6–8 weeks before planting out. Use a sterile seed mix; sow shallowly and keep 22–25°C until germination (typically 5–8 days). Provide strong light immediately after emergence (grow lights 14–16 h/day) and reduce temperature to 18–20°C by day, 16–18°C by night to prevent legginess. Prick out to individual pots at first true leaves. Pot up progressively to 1–3 L pots as roots fill. Begin gentle feeding once plants are well rooted. Harden off for 7–10 days before planting out when nights consistently stay above about 8–10°C.
Planting
Plant deeply so that the stem base is buried to the first true leaves to promote adventitious rooting (not for grafted plants—keep graft union above soil). Space determinate types about 40–60 cm apart; indeterminate 50–70 cm apart in rows 75–90 cm apart. Provide sturdy stakes, strings, or cages at planting. In containers, use at least 15–20 L per bush type and 25–40 L per indeterminate. Mulch with straw, grass clippings, or compost to conserve moisture and reduce soil splash. Outdoors, choose the warmest, sunniest, most sheltered spot, e.g., a south-facing wall.
Pruning
For indeterminate tomatoes, remove side shoots (suckers) weekly to maintain 1–2 main stems. Tie in as they grow. Remove lower leaves gradually to improve airflow and reduce disease; keep at least 30–40 cm of bare stem above the soil by mid-season. In Sweden, pinch out the growing tip in early to mid-August to focus energy on ripening existing trusses. Determinate (bush) types generally need no sucker removal; only tidy damaged or congested growth.
Maintenance
Keep soil evenly moist with deep, infrequent watering—avoid wet-dry swings. Ventilate greenhouses daily to reduce humidity and improve pollination. Feed organically every 7–14 days after the first fruits set with a potassium-rich liquid (e.g., comfrey tea or certified organic tomato feed). Add a light top-dressing of compost mid-season. Maintain consistent calcium uptake by steady watering; avoid excessive ammonium nitrogen. Consider yellow sticky traps and regular leaf inspections for pests. Mulch and avoid overhead watering to limit blight. Rotate away from beds that had potatoes or tomatoes last year.
Harvest
Harvest when fruits are fully colored and slightly soft to the touch. Pick little and often (2–3 times per week) to keep plants productive. Prefer harvesting when fruits are dry; in wet spells, pick before heavy rain to limit cracking. For truss types, cut the whole truss for ripening indoors if cold, damp weather threatens. Do not refrigerate; store at 12–16°C for best flavor. Late in the season, pick mature green fruits before frost and ripen indoors in a single layer with good air circulation.
Common issues
Late blight (Phytophthora infestans): prevent with dry foliage, wide spacing, pruning for airflow, and roof/cover outdoors; remove infected leaves promptly. Blossom end rot (calcium disorder): avoid moisture stress; consistent watering and balanced feeding help. Fruit cracking: reduce watering fluctuations and pick promptly after rains. Leaf curl from heat or pruning stress: usually temporary. Pests: aphids, whiteflies, spider mites—control with ventilation, biological controls (parasitoids, predatory mites), and gentle soap sprays if needed. Magnesium deficiency (interveinal chlorosis): correct with Epsom salt foliar only if diagnosed.
Rotation schedule
Rotate on a 4-year cycle away from all Solanaceae (tomato, potato, pepper, eggplant). Follow heavy feeders like tomatoes with legumes or leafy greens the next year. Avoid planting after potatoes to reduce blight and soil-borne diseases. In containers, refresh most of the potting mix annually.
Pollination
Self-pollinating flowers; gentle vibration (wind, bees, or manual tapping) improves fruit set, especially in greenhouses.
Companion plants
Basil, marigold (Tagetes), calendula, chives, garlic, nasturtium, lettuce.
Incompatible plants
Potato and other Solanaceae (pepper, eggplant) nearby increase disease pressure; fennel; avoid following potatoes/tomatoes in rotation.
