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Fertilising guide

How to fertilise Mexican Feather Grass (Nassella tenuissima)— schedule & NPK

Also called mexican feather grass, silky thread grass, angel hair grass.

More about mexican feather grass

About Mexican Feather Grass

Nassella tenuissima · also called mexican feather grass, silky thread grass · flowering

A fine-textured ornamental grass forming soft, flowing mounds of hair-thin green blades that ripple in the slightest breeze. Feathery silvery-green flower heads emerge in early summer, ageing to wheaten blonde. Drought-tolerant, sun-loving and graceful, it softens borders, gravel gardens and containers — though it self-seeds prolifically and is invasive in some regions.

Growth habit: Cool-season, clump-forming grass making a soft, fountaining mound of extremely fine, thread-like blades that move with the wind; semi-evergreen in mild climates, fading to straw-blonde in summer.

Watch for — Rot in wet or rich soil: Heavy, damp or fertile soil rots the crown and shortens its life. Plant in sharp-draining, lean ground and avoid overwatering.

What fertiliser mexican feather grass actually wants — and why

Mexican Feather Grass 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 mexican feather grass: 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 mexican feather grass, 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 mexican feather grass:

Needs no feeding and prefers lean conditions; fertiliser produces floppy, short-lived growth. Skip it entirely on poor soils. 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 mexican feather grass 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 mexican feather grass

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

Signs you are over-feeding mexican feather grass

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

Signs you are under-feeding mexican feather grass

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

Flushing and leaching the salts

Flush the pot of mexican feather grass 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 mexican feather grass

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 mexican feather grass — frequently asked questions

What fertiliser does mexican feather grass 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. Mexican Feather Grass 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 mexican feather grass?

Needs no feeding and prefers lean conditions; fertiliser produces floppy, short-lived growth. Skip it entirely on poor soils. Needs no feeding and prefers lean conditions; fertiliser produces floppy, short-lived growth. Skip it entirely on poor soils. 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 mexican feather grass?

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

What does over-feeding mexican feather grass 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 mexican feather grass 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 mexican feather grass?

Flush the pot of mexican feather grass 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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