Fertilising guide
How to fertilise Cosmos sulphureus 'Klondike' (Cosmos sulphureus 'Klondike')— schedule & NPK
Also called Klondike Sulphur Cosmos, Dwarf Orange Cosmos.
More about cosmos sulphureus 'klondike'
About Cosmos sulphureus 'Klondike'
Cosmos sulphureus 'Klondike' · also called Klondike Sulphur Cosmos, Dwarf Orange Cosmos · flowering
A compact, heat-loving annual prized for vivid orange and gold semi-double daisies that bloom from early summer to first frost. 'Klondike' is more compact than tall sulphur cosmos, thriving in poor, lean soils and full sun. Drought-tolerant once established, it self-seeds readily and draws bees, butterflies, and hoverflies all season.
Growth habit: Bushy, upright annual with finely divided, lance-shaped foliage and freely branching stems topped by single or semi-double flowers held above the leaves.
Watch for — Few flowers, lots of foliage: Caused by rich soil or feeding. Stop fertilising and grow in lean soil to restore prolific blooming.
What fertiliser cosmos sulphureus 'klondike' actually wants — and why
Cosmos sulphureus 'Klondike' flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.
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 cosmos sulphureus 'klondike': 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 cosmos sulphureus 'klondike', 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 cosmos sulphureus 'klondike':
Generally needs none. Feeding promotes leafy growth at the expense of flowers, so skip nitrogen feeds. A single low dose of balanced fertiliser at planting is the most it requires in poor soil. In practice: no routine feeding at all for cosmos sulphureus 'klondike' — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
The dormant-season rule matters more than the exact interval: skip feeding entirely when cosmos sulphureus 'klondike' 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 cosmos sulphureus 'klondike'
None is the correct answer for cosmos sulphureus 'klondike'. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
Feeding always goes onto already-damp soil, never dry roots — water cosmos sulphureus 'klondike' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cosmos sulphureus 'klondike' watering schedule.
Signs you are over-feeding cosmos sulphureus 'klondike'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for cosmos sulphureus 'klondike':
- Abundant leafy growth and very few flowers (the classic over-rich symptom).
- Soft, floppy stems and a sprawling, leafy habit.
- Scorched edges and salt crust if it has been fed in a container.
Signs you are under-feeding cosmos sulphureus 'klondike'
- Effectively never an issue — these plants flower on poverty.
- Only on genuinely dead soil: weak, thin growth and few blooms.
- A short-lived plant in completely spent container compost.
If the symptoms point at watering, light or roots rather than nutrition, the full cosmos sulphureus 'klondike' care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
If cosmos sulphureus 'klondike' has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Organic vs synthetic feeds for cosmos sulphureus 'klondike'
Organic options
A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.
Synthetic / liquid feeds
None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in cosmos sulphureus 'klondike'.
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 cosmos sulphureus 'klondike' — frequently asked questions
What fertiliser does cosmos sulphureus 'klondike' need?
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Cosmos sulphureus 'Klondike' flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
How often should I feed cosmos sulphureus 'klondike'?
Generally needs none. Feeding promotes leafy growth at the expense of flowers, so skip nitrogen feeds. A single low dose of balanced fertiliser at planting is the most it requires in poor soil. Generally needs none. Feeding promotes leafy growth at the expense of flowers, so skip nitrogen feeds. A single low dose of balanced fertiliser at planting is the most it requires in poor soil. In practice: no routine feeding at all for cosmos sulphureus 'klondike' — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
What strength of feed for cosmos sulphureus 'klondike'?
None is the correct answer for cosmos sulphureus 'klondike'. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
What does over-feeding cosmos sulphureus 'klondike' look like?
Abundant leafy growth and very few flowers (the classic over-rich symptom). Soft, floppy stems and a sprawling, leafy habit. Scorched edges and salt crust if it has been fed in a container. Feeding cosmos sulphureus 'klondike' at all — especially "to help it flower" — is the defining mistake. Rich soil gives you a big green plant and almost no blooms; restraint is what produces the flowers.
Should I flush the soil of cosmos sulphureus 'klondike'?
If cosmos sulphureus 'klondike' has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Keep reading
- Cosmos sulphureus 'Klondike' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water cosmos sulphureus 'klondike' — 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 peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 5561 fertilising guides in the Growli library