Nasturtium / Indian Cress
Tropaeolum majus
description
Nasturtium is an easy trailing annual with round leaves and colourful peppery edible flowers.
benefits
- Pet-friendly, non-toxic to animals
- Edible
- Suitable for containers
How to care for Nasturtium
sunlight
Native to open, sunny parts of the Andes, nasturtium flowers best where it receives plenty of direct light. Give it an unshaded outdoor spot or the brightest window you have.
Full sun
Ideal for strong growth and abundant flowers. Aim for about 6 or more hours of direct sun daily. A south- or west-facing position works well, provided the pot does not dry out too quickly.
Light shade - tolerated
In very hot climates, afternoon shade can prevent stress. Expect more leaves and fewer flowers if it receives only a few hours of direct sun.
watering
Water deeply until a little drains from the pot, then empty the saucer. Check the soil rather than following a fixed calendar: sun, heat, wind, pot size, and a fast-draining mix can all make it dry sooner.
Spring and summer growth
In a sunny container, expect to water about every 2-4 days, and daily during hot, windy weather. Water when the top 2-3 cm of soil feels dry and the pot is noticeably lighter. Plants in the ground usually need a thorough soak about once a week if rain is scarce.
Cooler or low-light weather
When growth slows, water roughly every 5-10 days in containers, only after the upper soil has dried. Nasturtiums are annuals, so reduce watering as plants fade rather than trying to keep declining plants constantly wet.
humidity
Preferred humidity
Native to open Andean regions, nasturtium is comfortable in average household air and does not need tropical humidity. Good airflow matters more than raising moisture around the leaves.
Acceptable range
It usually manages at around 30-60% relative humidity. Very dry, hot air can cause crisp leaf edges, limp growth despite moist soil, or flowers that fade quickly. Check watering and heat exposure too, as these cause similar symptoms.
- Move the pot back from heating vents or hot glass if the air is very dry.
- Use a pebble tray or humidifier nearby only if humidity stays below about 30%.
- Avoid frequent misting and crowded plants, which can encourage mildew.
temperature
Preferred temperatures
Keep above
Native to the cooler uplands of South America, nasturtium grows best in mild weather. It tolerates warm days, but flowering often slows once temperatures regularly rise above 27°C (80°F).
nutrition
March - August
Feed potted nasturtiums about every 3-4 weeks while they are actively growing, using a balanced liquid fertiliser at half strength. Plants in reasonably fertile garden soil usually need no extra feed. Stop when growth slows in autumn.
Nitrogen
Nitrogen supports leafy growth, but too much gives you lots of leaves and fewer flowers. Use a gentle feed rather than a rich lawn or high-nitrogen fertiliser.
Potassium
Potassium supports flowering and sturdy growth. A general flowering or balanced fertiliser provides enough when used lightly.
soil
Loose, well-draining soil
Nasturtiums root best in an airy mix that holds some moisture but never stays soggy. Use ordinary potting mix loosened with perlite or coarse sand. Avoid heavily enriched soil, which can produce lots of leaves and fewer flowers.
pH 6,0 - 7,5
This is slightly acidic to mildly alkaline, a range most all-purpose potting mixes suit well. For containers, choose a fresh peat-free or standard potting mix rather than trying to adjust pH.