Fertilising guide
How to fertilise Radicchio 'Rossa di Treviso' (Cichorium intybus var. foliosum 'Rossa di Treviso')— schedule & NPK
Also called Treviso radicchio, Italian chicory, Treviso red chicory.
More about radicchio 'rossa di treviso'
About Radicchio 'Rossa di Treviso'
Cichorium intybus var. foliosum 'Rossa di Treviso' · also called Treviso radicchio, Italian chicory · edible
'Rossa di Treviso' is an elongated Italian chicory forming upright, loose heads of wine-red leaves with bright white midribs. Cool weather and autumn frost intensify the colour and sweeten the pleasantly bitter leaves. A traditional cut-and-force crop, it is sown in summer for autumn and winter harvest in cooler climates.
Growth habit: Upright, loosely hearting rosette of elongated leaves on a single deep taproot; left unharvested in a second year it bolts to a tall branched flower stem with blue daisy flowers.
What fertiliser radicchio 'rossa di treviso' actually wants — and why
Radicchio 'Rossa di Treviso' feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.
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.
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 radicchio 'rossa di treviso': 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 radicchio 'rossa di treviso', 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 radicchio 'rossa di treviso':
Moderate feeder: incorporate compost before sowing, then a balanced feed or light nitrogen top-dressing mid-season supports leaf growth. Avoid heavy nitrogen late on, which produces soft growth prone to rot and poor red colouration in the heads. 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 radicchio 'rossa di treviso' 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 radicchio 'rossa di treviso'
Follow the crop-feed label rate for radicchio 'rossa di treviso' — 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 radicchio 'rossa di treviso' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the radicchio 'rossa di treviso' watering schedule.
Signs you are over-feeding radicchio 'rossa di treviso'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for radicchio 'rossa di treviso':
- 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 radicchio 'rossa di treviso'
- 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 radicchio 'rossa di treviso' 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 radicchio 'rossa di treviso' 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 radicchio 'rossa di treviso'
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 radicchio 'rossa di treviso' — frequently asked questions
What fertiliser does radicchio 'rossa di treviso' 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. Radicchio 'Rossa di Treviso' 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 radicchio 'rossa di treviso'?
Moderate feeder: incorporate compost before sowing, then a balanced feed or light nitrogen top-dressing mid-season supports leaf growth. Avoid heavy nitrogen late on, which produces soft growth prone to rot and poor red colouration in the heads. Moderate feeder: incorporate compost before sowing, then a balanced feed or light nitrogen top-dressing mid-season supports leaf growth. Avoid heavy nitrogen late on, which produces soft growth prone to rot and poor red colouration in the heads. 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 radicchio 'rossa di treviso'?
Follow the crop-feed label rate for radicchio 'rossa di treviso' — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.
What does over-feeding radicchio 'rossa di treviso' 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 radicchio 'rossa di treviso' 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 radicchio 'rossa di treviso'?
In containers, fertiliser salts build up fast — water radicchio 'rossa di treviso' 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.
Keep reading
- Radicchio 'Rossa di Treviso' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water radicchio 'rossa di treviso' — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise tomato
- How to fertilise pepper
- How to fertilise cucumber
- All 5561 fertilising guides in the Growli library