Fertilising guide

How to fertilise Nasturtium 'Alaska' (Tropaeolum majus 'Alaska')— schedule & NPK

Also called Variegated nasturtium.

More about nasturtium 'alaska'

About Nasturtium 'Alaska'

Tropaeolum majus 'Alaska' · also called Variegated nasturtium · edible

'Alaska' is a compact, bushy nasturtium grown for its cream-and-green marbled, variegated foliage as much as its bright red, orange and yellow flowers. Leaves and flowers are edible and peppery. A quick hardy annual, it flowers best on poor soil in full sun, suits pots and edges, and self-seeds freely after frost-free sowing.

Growth habit: Compact, mounding bushy annual with distinctive cream-marbled variegated leaves, ideal for containers, edging and the front of borders.

Watch for — All leaves, few flowers: Over-rich soil or feeding produces lush foliage with sparse blooms. Grow lean in poor soil and skip fertiliser.

What fertiliser nasturtium 'alaska' actually wants — and why

Nasturtium 'Alaska' feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for nasturtium 'alaska': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed nasturtium 'alaska', and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For nasturtium 'alaska':

Do not feed to boost flowers. Use at most a single weak balanced feed on very poor soil; nitrogen-rich fertiliser produces abundant leaves and few flowers. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

The dormant-season rule matters more than the exact interval: skip feeding entirely when nasturtium 'alaska' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for nasturtium 'alaska'

Follow the crop-feed label rate for nasturtium 'alaska' — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.

Feeding always goes onto already-damp soil, never dry roots — water nasturtium 'alaska' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the nasturtium 'alaska' watering schedule.

Signs you are over-feeding nasturtium 'alaska'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for nasturtium 'alaska':

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
Lush foliage hiding the crop; soft growth prone to pests and disease.
Salt crust on the soil and scorched leaf edges in containers.

Signs you are under-feeding nasturtium 'alaska'

Pale, yellowing lower leaves and stunted growth.
Small fruit, poor set, and a quickly exhausted plant.
Blossom-end rot and weak cropping from erratic or insufficient feeding.

If the symptoms point at watering, light or roots rather than nutrition, the full nasturtium 'alaska' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

In containers, fertiliser salts build up fast — water nasturtium 'alaska' thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.

Organic vs synthetic feeds for nasturtium 'alaska'

Organic options

Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.

Synthetic / liquid feeds

A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising nasturtium 'alaska' — frequently asked questions

What fertiliser does nasturtium 'alaska' need?

Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Nasturtium 'Alaska' feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

How often should I feed nasturtium 'alaska'?

Do not feed to boost flowers. Use at most a single weak balanced feed on very poor soil; nitrogen-rich fertiliser produces abundant leaves and few flowers. Do not feed to boost flowers. Use at most a single weak balanced feed on very poor soil; nitrogen-rich fertiliser produces abundant leaves and few flowers. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

What strength of feed for nasturtium 'alaska'?

What does over-feeding nasturtium 'alaska' look like?

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once nasturtium 'alaska' starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.

Should I flush the soil of nasturtium 'alaska'?