🌿 Nasturtium

Nasturtiums thrive in light, well-aerated, non-draining soil of low to medium fertility. Soils that are too rich or have a high nitrogen content favor leaf growth and flower decline. A sandy or silty substrate is ideal. Avoid heavy, water-logged clays; improve structure and drainage with gravel or coarse sand and, where appropriate, modest amounts of organic matter (avoid excess manure or heavy fertilizers). Best performance is generally obtained in slightly acidic to neutral conditions (around pH 6-7). For containers, use a loose, well-drained potting mix (e.g. multi-purpose compost) cut with perlite/sand, and provide plenty of drainage holes; don't let the compost remain constantly damp.

Timing: Sow after the risk of heavy frost has passed; nasturtiums are sensitive to frost. In cool, short-season climates, start sowing under cover about 4 to 6 weeks before the last expected frost, then harden off and plant once the nights are mild and the soil has warmed up. Location and soil: Sow/plant in full sun or light shade, in well-drained soil. Nasturtiums flower best in moderately fertile to lean soils; avoid very rich soils or a diet rich in nitrogen, which can favor leaf growth to the detriment of flowers. Direct sowing: Sow plants where they will flower, to avoid the shock of transplanting. Plant the large seeds at a depth of 2-3 cm, tamp gently and water. Optional: soak the seeds for 12 to 24 hours (or slightly score the seed coat) to accelerate and homogenize germination. Germination: Keep soil evenly moist, but not soggy. Seeds generally germinate in 7 to 14 days in mild heat (around 15 to 20°C). Spacing: Thin/spacing seedlings by about 20-30 cm for compact/shrubby forms. Leave a space of 30-45 cm (or provide support) for climbing species. Starting indoors / Transplanting: If starting indoors, sow in individual modules or biodegradable pots to minimize root disturbance, as nasturtiums do not tolerate transplanting. Plant carefully, keeping the root ball intact after hardening off, and water well until the plant is established.

Nasturtiums (Tropaeolum spp.) flower best in low- to medium-fertility soil. In flowerbeds, fertilizers are generally unnecessary. If the soil is very poor, add a small amount of compost at planting time, but avoid rich manure. Do not apply fertilizers with a high nitrogen content, as they promote leaf growth and reduce flowering. If nutrients are required, choose a low-nitrogen product or a balanced, low-dose product (avoid large doses). In containers (where nutrients are leached out more quickly), fertilize only if growth is weak or leaves are pale: apply a half-dose balanced liquid fertilizer about every 3-4 weeks during active growth, then reduce/stop if plants become lush and flowering diminishes. Avoid fertilizing at the end of the season or when plants are growing and flowering well.

Nasturtium (Tropaeolum majus) is traditionally used as an antiscorbutic, as fresh leaves and flowers contain vitamin C, and in folk medicine for mild respiratory and urinary disorders. The plant contains glucosinolates (notably glucotropoline) which enzymatically produce isothiocyanates (e.g. benzyl isothiocyanate), compounds whose antimicrobial activity has been demonstrated in laboratory studies. Nasturtium has also been used as a mild diuretic and topically for skin problems or minor wounds, but solid clinical evidence of specific therapeutic results from nasturtium alone remains limited.