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Fertilising guide

How to fertilise Sea Lettuce (Dudleya caespitosa)— schedule & NPK

Also called Sea Lettuce, Coast Dudleya, Cliffrose.

More about sea lettuce

About Sea Lettuce

Dudleya caespitosa · also called Sea Lettuce, Coast Dudleya · houseplant

Dudleya caespitosa is a California native succulent forming rosettes of fleshy, blue-green leaves dusted with a chalky white farina. It thrives in coastal conditions with cool dry summers and moist mild winters, making it unusual among succulents. Excellent for rock gardens and terracotta pots on bright, cool windowsills.

Growth habit: Compact clustering rosette-forming succulent; slow-growing

What fertiliser sea lettuce actually wants — and why

Sea Lettuce 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 sea lettuce: 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 sea lettuce, 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 sea lettuce:

Feed once at the start of the active growing season (autumn) with a very dilute, low-nitrogen succulent fertiliser. Excess fertiliser causes lush, weak growth that is prone to rot. 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 sea lettuce 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 sea lettuce

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

Signs you are over-feeding sea lettuce

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

Signs you are under-feeding sea lettuce

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

Flushing and leaching the salts

Flush the pot of sea lettuce 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 sea lettuce

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 sea lettuce — frequently asked questions

What fertiliser does sea lettuce 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. Sea Lettuce 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 sea lettuce?

Feed once at the start of the active growing season (autumn) with a very dilute, low-nitrogen succulent fertiliser. Excess fertiliser causes lush, weak growth that is prone to rot. Feed once at the start of the active growing season (autumn) with a very dilute, low-nitrogen succulent fertiliser. Excess fertiliser causes lush, weak growth that is prone to rot. 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 sea lettuce?

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

What does over-feeding sea lettuce 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 sea lettuce 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 sea lettuce?

Flush the pot of sea lettuce 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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