Fertilising guide
How to fertilise 'Purple Sprouting' Broccoli (Brassica oleracea var. italica 'Purple Sprouting')— schedule & NPK
Also called Purple sprouting broccoli, PSB.
More about 'purple sprouting' broccoli
About 'Purple Sprouting' Broccoli
Brassica oleracea var. italica 'Purple Sprouting' · also called Purple sprouting broccoli, PSB · edible
Purple sprouting broccoli is a hardy, overwintering brassica grown for masses of slender purple flower shoots in late winter and spring, rather than a single head. Sown in late spring, it stands through winter cold (which it needs to crop well) before bursting into productive spears. It demands firm, fertile soil, full sun, staking, and patience over its long 9-12 month season.
Growth habit: Tall, robust, branching brassica that builds a large leafy framework through summer and autumn, then produces dozens of purple flowering side-shoots from the leaf axils in late winter and spring.
Watch for — Clubroot: Soil-borne disease that swells and rots roots, stunting plants over the long season. Lime to near-neutral pH, improve drainage, and rotate brassicas on a 3-4 year cycle.
What fertiliser 'purple sprouting' broccoli actually wants — and why
'Purple Sprouting' Broccoli is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.
A nitrogen-leaning feed (higher first number) or compost-rich soil — nitrogen drives the fast, tender leafy growth this crop is grown for. Phosphorus and potassium matter far less here than for fruiting crops.
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 'purple sprouting' broccoli: 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 'purple sprouting' broccoli, 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 'purple sprouting' broccoli:
Feed for a long season. Incorporate a balanced base fertiliser at planting, then side-dress with nitrogen in late summer to build a strong frame. A spring feed as growth resumes boosts spear production; avoid heavy nitrogen mid-winter. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).
The dormant-season rule matters more than the exact interval: skip feeding entirely when 'purple sprouting' broccoli 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 'purple sprouting' broccoli
Use the vegetable-feed label rate for 'purple sprouting' broccoli. Steady availability matters more than a strong dose — a check in growth makes leaves tough and can trigger bolting.
Feeding always goes onto already-damp soil, never dry roots — water 'purple sprouting' broccoli first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the 'purple sprouting' broccoli watering schedule.
Signs you are over-feeding 'purple sprouting' broccoli
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for 'purple sprouting' broccoli:
- Very soft, floppy, dark-green growth that attracts aphids.
- Excess leafy growth at the expense of hearts/heads in cabbage and the like.
- Salt crust and scorched leaf edges in containers; nitrate-heavy leaves.
Signs you are under-feeding 'purple sprouting' broccoli
- Pale, yellow-green leaves, oldest first, and slow growth.
- Small, tough, bitter leaves and premature bolting.
- Weak, stunted heads in cabbage, broccoli and cauliflower.
If the symptoms point at watering, light or roots rather than nutrition, the full 'purple sprouting' broccoli care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
For container-grown 'purple sprouting' broccoli, water until it drains freely each time and flush pots monthly with plain water to stop nitrogen salts accumulating; in the ground, good compost levels naturally buffer this.
Organic vs synthetic feeds for 'purple sprouting' broccoli
Organic options
Well-rotted manure or compost dug in, plus nitrogen-rich liquid feeds like diluted chicken-manure pellets or nettle feed. UK: pelleted chicken manure or Westland; US: Espoma Garden-tone or blood meal. Steady and soil-building.
Synthetic / liquid feeds
A balanced feed at planting then a high-nitrogen liquid or granular side-dress — UK: Growmore then a nitrogen feed or Phostrogen; US: a 10-10-10 then a high-N (e.g. 21-0-0) side-dress or Miracle-Gro.
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 'purple sprouting' broccoli — frequently asked questions
What fertiliser does 'purple sprouting' broccoli need?
A nitrogen-leaning feed (higher first number) or compost-rich soil — nitrogen drives the fast, tender leafy growth this crop is grown for. Phosphorus and potassium matter far less here than for fruiting crops. 'Purple Sprouting' Broccoli is grown entirely for its leaves, so nitrogen is the priority — steady, nitrogen-leaning feeding keeps it growing fast, tender and unbolted.
How often should I feed 'purple sprouting' broccoli?
Feed for a long season. Incorporate a balanced base fertiliser at planting, then side-dress with nitrogen in late summer to build a strong frame. A spring feed as growth resumes boosts spear production; avoid heavy nitrogen mid-winter. Feed for a long season. Incorporate a balanced base fertiliser at planting, then side-dress with nitrogen in late summer to build a strong frame. A spring feed as growth resumes boosts spear production; avoid heavy nitrogen mid-winter. In practice: a balanced or compost-rich start, then a nitrogen side-dress or liquid feed every 3-4 weeks through the cropping period in the main season (spring through early autumn).
What strength of feed for 'purple sprouting' broccoli?
Use the vegetable-feed label rate for 'purple sprouting' broccoli. Steady availability matters more than a strong dose — a check in growth makes leaves tough and can trigger bolting.
What does over-feeding 'purple sprouting' broccoli look like?
Very soft, floppy, dark-green growth that attracts aphids. Excess leafy growth at the expense of hearts/heads in cabbage and the like. Salt crust and scorched leaf edges in containers; nitrate-heavy leaves. Letting 'purple sprouting' broccoli run short of nitrogen mid-crop is the main mistake — growth checks, leaves toughen and brassicas/leafy greens bolt or turn bitter. Keep nitrogen steadily available.
Should I flush the soil of 'purple sprouting' broccoli?
For container-grown 'purple sprouting' broccoli, water until it drains freely each time and flush pots monthly with plain water to stop nitrogen salts accumulating; in the ground, good compost levels naturally buffer this.
Keep reading
- 'Purple Sprouting' Broccoli care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water 'purple sprouting' broccoli — 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 1284 fertilising guides in the Growli library