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Fertilising guide

How to fertilise Flowering coleus (Plectranthus scutellarioides)— schedule & NPK

Also called painted nettle, coleus.

About Flowering coleus

Plectranthus scutellarioides · also called painted nettle, coleus · flowering

Flowering coleus is the same species as foliage coleus, here grown for late-summer spikes of small blue or lavender flowers above colourful leaves. Pinch flowers to extend foliage life if grown for leaves. Mildly toxic to pets through essential oils.

Coleus (Coleus / Plectranthus scutellarioides) belongs to a large Old World mint-family group of roughly 350 species of annuals, perennials and semi-succulents from Africa and tropical Asia; grown for foliage, not bloom.

Light, regular balanced feeding sustains vivid leaf color; over-feeding and low light both dull the foliage pigments it is grown for.

Growth habit: Bushy tender perennial; pinch regularly

Sources: extension.umn.edu, missouribotanicalgarden.org, rhs.org.uk

What fertiliser flowering coleus actually wants — and why

Flowering coleus is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.

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 flowering coleus: 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 flowering coleus, 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 flowering coleus:

Half-strength balanced feed every 2-3 weeks. Treat that as every 2-3 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

The dormant-season rule matters more than the exact interval: skip feeding entirely when flowering coleus 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 flowering coleus

Half strength is the safe default for flowering coleus — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

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

Signs you are over-feeding flowering coleus

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

Signs you are under-feeding flowering coleus

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

Flushing and leaching the salts

Flush the pot of flowering coleus with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

Organic vs synthetic feeds for flowering coleus

Organic options

A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.

Synthetic / liquid feeds

A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.

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 flowering coleus — frequently asked questions

What fertiliser does flowering coleus need?

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Flowering coleus is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

How often should I feed flowering coleus?

Half-strength balanced feed every 2-3 weeks. Half-strength balanced feed every 2-3 weeks. Treat that as every 2-3 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

What strength of feed for flowering coleus?

Half strength is the safe default for flowering coleus — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding flowering coleus look like?

Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding flowering coleus year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.

Should I flush the soil of flowering coleus?

Flush the pot of flowering coleus with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

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