Fertilising guide

How to fertilise Moss rose (Portulaca grandiflora)— schedule & NPK

Also called moss rose, sun plant, portulaca, rose moss, eleven o'clock.

More about moss rose

About Moss rose

Portulaca grandiflora · also called moss rose, sun plant · flowering

Moss rose is a sun-loving, drought-tolerant South American annual grown for its jewel-bright single or double flowers in scarlet, yellow, orange, pink, white and bicolours above succulent needle-like foliage. It thrives in hot, dry conditions in poor soil and is ideal for sunny borders, rock gardens, containers and paving gaps. Listed by ASPCA as toxic to pets.

Growth habit: Low-growing trailing or mounding warm-season annual

Watch for — Aphid infestations: Soft new growth can attract aphid colonies — knock off with a strong jet of water or apply insecticidal soap; avoid heavy nitrogen feeding which produces the lush growth aphids prefer.

What fertiliser moss rose actually wants — and why

Moss rose 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 moss rose: 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 moss rose, 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 moss rose:

Minimal feeding required — too much nitrogen produces foliage at the expense of flowers. A single application of balanced granular fertiliser at planting is sufficient. In containers, a half-strength liquid feed once a month is adequate. In practice: no routine feeding at all for moss rose — 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 moss rose 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 moss rose

None is the correct answer for moss rose. 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 moss rose first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the moss rose watering schedule.

Signs you are over-feeding moss rose

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

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 moss rose

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 moss rose care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

If moss rose 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 moss rose

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 moss rose.

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 moss rose — frequently asked questions

What fertiliser does moss rose 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. Moss rose 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 moss rose?

Minimal feeding required — too much nitrogen produces foliage at the expense of flowers. A single application of balanced granular fertiliser at planting is sufficient. In containers, a half-strength liquid feed once a month is adequate. Minimal feeding required — too much nitrogen produces foliage at the expense of flowers. A single application of balanced granular fertiliser at planting is sufficient. In containers, a half-strength liquid feed once a month is adequate. In practice: no routine feeding at all for moss rose — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for moss rose?