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Fertilising guide

How to fertilise Rose of Sharon 'Diana' (Hibiscus syriacus 'Diana')— schedule & NPK

Also called White Rose of Sharon.

More about rose of sharon 'diana'

About Rose of Sharon 'Diana'

Hibiscus syriacus 'Diana' · also called White Rose of Sharon · flowering

Hibiscus syriacus 'Diana' is a US National Arboretum selection bearing very large, pure-white single flowers without the usual red throat. The blooms stay open longer into the evening, and the plant is largely sterile, so it self-seeds little. It flowers heavily from midsummer to autumn on an upright shrub, making a clean, luminous late-season feature.

Growth habit: Upright, rounded to vase-shaped deciduous shrub, multi-stemmed, dense, and a vigorous, tetraploid grower producing notably large flowers. Leafs out late; tolerates and benefits from late-winter pruning to shape and boost flower size.

What fertiliser rose of sharon 'diana' actually wants — and why

Rose of Sharon 'Diana' 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 rose of sharon 'diana': 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 rose of sharon 'diana', 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 rose of sharon 'diana':

Feed in early spring with a balanced slow-release fertiliser and lightly again in early summer to sustain the long flowering season. Limit nitrogen, which favours foliage; potassium-rich feeds encourage more and larger blooms. Treat that as sparingly through the growing season 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 rose of sharon 'diana' 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 rose of sharon 'diana'

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

Signs you are over-feeding rose of sharon 'diana'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for rose of sharon 'diana':

Signs you are under-feeding rose of sharon 'diana'

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

Flushing and leaching the salts

Flush the pot of rose of sharon 'diana' 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 rose of sharon 'diana'

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 rose of sharon 'diana' — frequently asked questions

What fertiliser does rose of sharon 'diana' 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. Rose of Sharon 'Diana' 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 rose of sharon 'diana'?

Feed in early spring with a balanced slow-release fertiliser and lightly again in early summer to sustain the long flowering season. Limit nitrogen, which favours foliage; potassium-rich feeds encourage more and larger blooms. Feed in early spring with a balanced slow-release fertiliser and lightly again in early summer to sustain the long flowering season. Limit nitrogen, which favours foliage; potassium-rich feeds encourage more and larger blooms. Treat that as sparingly through the growing season 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 rose of sharon 'diana'?

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

What does over-feeding rose of sharon 'diana' 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 rose of sharon 'diana' 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 rose of sharon 'diana'?

Flush the pot of rose of sharon 'diana' 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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