Fertilising guide

How to fertilise Woolly Jerusalem Sage (Phlomis lanata)— schedule & NPK

Also called Woolly Jerusalem sage, Woolly phlomis.

More about woolly jerusalem sage

About Woolly Jerusalem Sage

Phlomis lanata · also called Woolly Jerusalem sage, Woolly phlomis · flowering

Phlomis lanata is a low, mound-forming, evergreen sub-shrub native to Crete and the Greek islands, where it grows on dry rocky hillsides and garrigue scrub. It is prized for its exceptionally dense, white-woolly leaves and whorls of bright yellow flowers borne in late spring and early summer. Excellent drainage and full sun are non-negotiable — this species is very intolerant of winter wet. Phlomis lanata is not listed on the ASPCA database; it is classified here as mildly-toxic due to insufficient confirmed safety data.

Growth habit: Low, compact, dome-shaped evergreen sub-shrub with densely woolly-white stems and leaves.

Watch for — Legginess and poor flowering: Lack of adequate sun or over-feeding with nitrogen causes weak, sprawling growth and fewer flowers; cut back lightly after flowering to maintain a compact shape.

What fertiliser woolly jerusalem sage actually wants — and why

Woolly Jerusalem Sage 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 woolly jerusalem sage: 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 woolly jerusalem sage, 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 woolly jerusalem sage:

Apply a very light, low-nitrogen feed in spring only; this species thrives in poor soils and excess nutrients produce excessive leafy growth at the expense of flowers. In practice: no routine feeding at all for woolly jerusalem sage — 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 woolly jerusalem sage 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 woolly jerusalem sage

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

Signs you are over-feeding woolly jerusalem sage

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

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 woolly jerusalem sage

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 woolly jerusalem sage care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

If woolly jerusalem sage 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 woolly jerusalem sage

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 woolly jerusalem sage.

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 woolly jerusalem sage — frequently asked questions

What fertiliser does woolly jerusalem sage 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. Woolly Jerusalem Sage 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 woolly jerusalem sage?

Apply a very light, low-nitrogen feed in spring only; this species thrives in poor soils and excess nutrients produce excessive leafy growth at the expense of flowers. Apply a very light, low-nitrogen feed in spring only; this species thrives in poor soils and excess nutrients produce excessive leafy growth at the expense of flowers. In practice: no routine feeding at all for woolly jerusalem sage — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for woolly jerusalem sage?