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Fertilising guide

How to fertilise Twinspur (Diascia barberae)— schedule & NPK

Also called Twinspur, Barbera twinspur.

More about twinspur

About Twinspur

Diascia barberae · also called Twinspur, Barbera twinspur · flowering

Twinspur is a dainty South African annual or short-lived perennial producing masses of small pink to coral tubular flowers with characteristic twin spurs on slender branching stems. It excels in cool-season gardens, window boxes, and hanging baskets, blooming most prolifically in spring and autumn when temperatures remain mild.

Growth habit: Low, branching, semi-trailing annual or short-lived perennial

What fertiliser twinspur actually wants — and why

Twinspur 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 twinspur: 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 twinspur, 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 twinspur:

Feed every 2 weeks with a balanced liquid fertiliser or a high-potassium bloom formula during active flowering. In containers, begin feeding 4–6 weeks after planting. Treat that as every 2 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 twinspur 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 twinspur

Half strength is the safe default for twinspur — 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 twinspur first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the twinspur watering schedule.

Signs you are over-feeding twinspur

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

Signs you are under-feeding twinspur

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

Flushing and leaching the salts

Flush the pot of twinspur 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 twinspur

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 twinspur — frequently asked questions

What fertiliser does twinspur 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. Twinspur 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 twinspur?

Feed every 2 weeks with a balanced liquid fertiliser or a high-potassium bloom formula during active flowering. In containers, begin feeding 4–6 weeks after planting. Feed every 2 weeks with a balanced liquid fertiliser or a high-potassium bloom formula during active flowering. In containers, begin feeding 4–6 weeks after planting. Treat that as every 2 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 twinspur?

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

What does over-feeding twinspur 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 twinspur 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 twinspur?

Flush the pot of twinspur 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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